THE DoD HIGH PERFORMANCE COMPUTING

MODERNIZATION PROGRAM IN 2002: MOVING DoD

COMPUTATIONAL SCIENCE FORWARD

Larry P. Davis

DoD High Performance Computing Modernization Office

1010 North Glebe Rd. Suite 510

Arlington, VA 22201-4795 USA

larryd@hpcmo.hpc.mil

The DoD High Performance Computing Modernization Program (HPCMP) has

completed several significant changes in 2001. Several major acquisitions have now

been concluded that will further improve the ability of the HPCMP to serve its DoD

science and technology and test and evaluation user base. The results of these

acquisitions are major additions of HPC hardware, software, and networking capabilities.

The HPCMP also continues its annual process to select and implement a set of missioncritical, computationally-intensive DoD Challenge Projects. These DoD Challenge

Projects ensure that DoD’s large, high-priority computational projects have access to

HPC resources that are needed for timely progress in their support of DoD laboratories

and test centers.

Computational chemistry and materials science (CCM) is one of the major computational

technology areas (CTAs) that characterize the computational work of DoD’s laboratories

and test centers. An appreciable number of DoD’s 4,000 laboratory and test center HPC

users and an appreciable fraction of its total high performance computing requirements

encompass CCM. Of the 41 active DoD Challenge Projects, several involve CCM.

These CCM Challenge Projects have made substantial progress for the design of DoD

materials.
NANOSCOPIC ORIGINS OF MATERIALS FAILURE

Emily Carter

Department of Chemistry and Biochemistry

Box 951569

University of California at Los Angeles

Los Angeles, CA 90095-1569, USA

eac@chem.ucla.edu

Empirically, it is known that spray coating thin layers of ceramics onto metals can afford

protection of the metal from both chemical corrosion and heat. For example, thin metal

oxide coatings are used to protect Ni alloy components of gas turbine engines from the

harsh operating conditions present during fuel combustion. The problem with current

coating formulations is that they spall (chip off) after a number of heating and cooling

cycles, which limits the practical lifetime of such ceramic coatings. The mechanisms of

how the coatings fail remain less than clear. Experimental measurements of the intrinsic

adhesion strengths of these coatings are difficult at best and tend to vary significantly due

to the presence of defects, voids, etc., created upon sample preparation. It is virtually

impossible to create an ideal interface and to reproducibly measure the work of

separation of such an interface. Here is an arena where theory may play a constructive

role, by systematically assessing the inherent stability of interfaces between materials.

Therefore, we have carried out a series of studies utilizing density functional theory with

periodic boundary conditions designed to characterize the adhesion and bonding at ideal

interfaces between ceramics and metals. Our investigations of the electronic and

mechanical properties of high temperature ceramics, such as alumina, zirconia, and silica,

and their interactions with Ni and Ni-Al alloy surfaces reveal why certain thin films of

ceramics do not adhere well to nickel and Ni-Al alloys, while others do. Insights from

these simulations are used to suggest new designs for alloy bond coatings that should

improve adhesion (and hence lifetime) of ceramic coatings on metals.

This work was supported by the Air Force Office of Scientific Research and by a

Department of Defense Challenge grant for computing resources.
SCALABLE ALGORITHMS AND PARALLEL COMPUTING

FRAMEWORK FOR MULTISCALE MATERIALS SIMULATIONS

BEYOND TERAFLOP

Aiichiro Nakano,

1

 T J. Campbell,2 R K. Kalia,1 E Lidorikis,3 S Ogata,4 F Shimojo,5

P Vashishta,1

1

Concurrent Computing Laboratory for Materials Simulations, Biological Computation

and Visualization Center, Department of Computer Science, Department of Physics &

Astronomy, Louisiana State University

Baton Rouge, LA 70803

2

Naval Oceanographic Office Major Shared Resource Center

3

Department of Physics, Massachusetts Institute of Technology

4

Department of Applied Sciences, Yamaguchi University, Japan

5

Faculty of Integrated Arts & Sciences, Hiroshima University

aiichiro@bit.csc.lsu.edu

Petaflop computers and a Grid of distributed supercomputers will offer tremendous

opportunities for high-end computational materials research. To make applications

scalable on such platforms, we are developing:

• Scalable linear-scaling algorithms based on space-time multiresolution

schemes—clustering, hierarchical abstraction, and the analysis of

asymptotic solution properties and error bound—for i) all-pairs function

evaluation in the N-body problem, ii) dense linear system of equations in

the variable N-charge problem, and iii) exhaustive combinatorial

enumeration in the quantum N-body problem, which are common in many

scientific/engineering applications;

• Multiscale simulation approach that seamlessly combines i) engineering

mechanics calculation based on the finite element (FE) method, ii)

atomistic simulation based on the molecular dynamics (MD) method, and

iii) quantum mechanical (QM) calculation based on the density functional

theory (DFT), so that expensive (often scalability-limiting) computations

are performed only when and where they are needed.

The production-quality programs also feature wavelet-based computational-space

decomposition for adaptive load balancing, spacefilling-curve-based adaptive data

compression with user-defined error bound for scalable I/O, and parallel/distributed

visibility culling for immersive and interactive visualization of massive simulation data.

Work supported by NSF, DOE, AFOSR, ARL, DOD DURINT, NASA, and the Louisiana

Board of Regents.
TERASCALE COMPUTING AT PSC

Ralph Roskies

Scientific Director

Pittsburgh Supercomputing Center

4400 Fifth Avenue

Pittsburgh, PA 15213 USA

roskies@psc.edu

I will discuss

the architecture of the Terascale machine at the Pittsburgh Supercomputing Center,

some challenges involved in working with a system this size,

benchmarks of actual performance on user codes,

examples of the groundbreaking science that has been done and will be done using

these facilities,

what the next generation of machines is likely to be

I will also describe how conference participants can get allocations on these and other

NSF facilities.
HIGH PERFORMANCE COMPUTING, COMPUTATIONAL GRID,

AND NUMERICAL LIBRARIES

Jack J. Dongarra

Computer Science Department

University of Tennessee

104 Ayres Hall

Knoxville, TN 37996-1301

dongarra@cs.utk.edu

In this talk we will look at how High Performance computing has changed over the last

10-years and look toward the future in terms of trends. In addition, we advocate the

`Computational Grids' to support `large-scale' applications. These must provide

transparent access to the complex mix of resources - computational, networking, and

storage - that can be provided through aggregation of resources. The vision is of

uniform, location independent, and transient access to the

 Computational

 Catalogued data

 Instrument system

 Human collaborator

resources of contemporary research activity in order to facilitate the solution of largescale, complex, multi-institutional/multidisciplinary data and computational based

problems. It envisages these resources being accessible through a Problem Solving

Environment appropriate to the target community.
TERASCALE OPTIMAL PDE SOLVERS

David E. Keyes

Department of Computer Science

Old Dominion University

Norfolk, VA 23529-0162 USA

dkeyes@lions.odu.edu

Computational performance on full-scale scientific applications, as tracked by the

Gordon Bell prize, has increased by four orders of magnitude since the prize was first

awarded in 1988 --- twenty-five times greater than can accounted for by Moore's Law

alone. The extra factor comes from process concurrency, which is as much as 8,192-fold

on the $100M "ASCI White" machine at Lawrence Livermore, currently ranked as the

world's most powerful. Though architectural concurrency is easy to achieve, algorithmic

concurrency to match is less so in scientific codes. Intuitively, this is due to global

domains of influence in many problems presented to the computer as implicitly

discretized operator equations --- implicitness being all but legislated for multiscale

systems, in which dynamics fast relative to dynamics of interest must be "stepped over."

For many years, we have been pursuing optimal parallel algorithms for PDE simulations

in the Newton-Krylov methodology, preconditioned with Schur and Schwarz

decompositions, including multilevel generalizations of the latter. A characteristic of this

family of algorithms is multiple discrete representations of the underlying continuous

operators --- high fidelity on the right-hand side and various shortcuts on the left-hand

side, including physics-based operator-splitting. Simultaneous advances in objectoriented software engineering have enabled the construction of complex software systems

in which these algorithmic elements can be combined modularly, recursively, and

relatively efficiently in parallel. Recently, we have helped show how large-scale PDEconstrained optimization (e.g., design, control, parameter identification --- usually the

ultimate practical problem behind the proximate PDE) can be placed into the same

algorithmic framework.

In this talk, we first focus on basic algorithmic methodology, we illustrate with a

university-NASA-DOE collaboration that led to a recent Gordon Bell prize, and finally

we describe major goals of a five-year, nine-institution project, "Terascale Optimal PDE

Simulations," which is one of the seven "Integrated Software Infrastructure Centers" of

the DOE's new "Scientific Discovery through Advanced Computing" initiative whose

aim is to package several existing license-free DOE software toolkits -- including

Argonne's PETSc and Livermore's HYPRE -- for wider community use.
AIR FORCE RESEARCH IN NANOENERGETICS – POTENTIAL

ADVANTAGES AND CHALLENGES

William H. Wilson, M P. Kramer and R W. Armstrong

Air Force Research Laboratory

Energetic Materials Branch, Ordnance Division

AFRL/MNME

Eglin AFB, FL 32542-1602, USA

William.wilson2@eglin.af.mil

The Advanced Energetics group at the AFRL Munitions Directorate is developing new,

emerging types of energetic materials. The broad goal is to exploit new types of

energetic materials to improve conventional munitions performance or capabilities. One

class of these alternative materials is based upon intermolecular reactions in materials

that have greater chemical energy per unit volume than conventional high explosives.

These materials have potential to provide very high temperature, high heat, and tunable

partitioning of energy into blast and metal acceleration. However, reaction and energy

release rates in micron-sized materials of this type, such as traditional pyrotechnic

materials, are too slow to achieve the power needed for conventional weapons effects.

One approach we are now pursuing is to promote very high-rate reaction in mixtures of

nano-scale fuels and oxidizers. Nanometric fuel-oxidizer systems that release energy at

power levels comparable to that of conventional uni-molecular HCNO-explosives are

being studied for munitions and propulsion applications. Reaction rates are accelerated

by reducing particle size to nanometric scale, increasing surface area for a given mass,

and reducing diffusion path lengths.

One disadvantage in reduction to nanometric scale is that inert surface layers become a

significant proportion of total mass. Processing disadvantages are also encountered.

Nano-particles tend to agglomerate, making it difficult to mix and homogeneously

distribute the material. Viscosity of mixes is significantly increased due to high specific

surface area. To minimize these practical difficulties, we have been studying the use

coatings to reduce surface tension and tendency to agglomerate. Techniques are being

developed for direct polymer encapsulation of nano-particles. Nano-thin layers of other

types of energetic materials, such as conventional explosives, coated onto the nanometric

metal fuel particles have also been developed as part of this work. Small-scale safety

tests of these coated energetic composites surprisingly have indicated that their safety

properties materials may be superior to that of conventional micron-sized explosive

particles.
STRENGTH AND PLASTICITY IN NANOCRYSTALLINE CU AND

NI -ATOMIC SCALE SIMULATIONS AND EXPERIMENTAL

OBSERVATIONS

M.-J. Caturla, C. Schuh, T. G. Nieh, J. S. Stölken, and Tomas Diaz de la Rubia

Chemistry and Materials Science Department

Lawrence Livermore National Lab.

L-268 P.O. Box 808

Livermore, CA 94550 USA

delarubia@llnl.gov

We present atomistic simulations of nanocrystalline materials under deformation.

These large-scale molecular dynamics simulations are performed in parallel

computers such as the ASCI machines at Lawrence Livermore National

Laboratory, that allow for systems containing several millions of atoms. We study

mainly two metals, copper and nickel, using the modified embedded atom model.

Our simulations start with a Gaussian distribution of grain sizes, with average

grain sizes up to 30nm in order to mimic the distributions observed

experimentally. The construction of the grains is such that the orientation of the

grain boundaries can be selected. Previous simulations with mainly high angle

grain boundaries have shown that deformation at grain sizes between 12 and

20nm is driven by intra-grain dislocation activity [1]. Recent experiments by Lu

et al. reported high ductility for electrodeposited nanocrystalline Cu at room

temperature. An important characteristic of this material is the presence of high

concentration of low angle grain boundaries. In order to address this problem, we

compare the results of simulations with random grain boundaries to those with

texture, low angle grain boundaries, identifying the deformation mechanisms. 

Our simulations show higher dislocation activity for the case of low angle grain

boundaries, with partial dislocations traveling across grains. The results of these

simulations are compared to experimental observations of electrodeposited 

nanocrystalline nickel .

Some experiments have also shown a dependence of ductility on strain rate. High

strain rates can be achieved using laser driven experiments. We will present the

evolution of a nanocrystalline material under laser driven shocks in the particular

case of converging shocks, and compare the results with simulations in single

crystals. These simulations show the importance of anisotropies due to crystal

orientation and grain boundaries in the shock induced damage, such as void

nucleation and growth.

[1] H. Van Swygenhoven, M. Spaczer, A. Caro, Acta Mater. Vol. 47, pp 3117

(1999)

This work was carried out under the auspices of the US Department of Energy by

Lawrence Livermore National Laboratory under contract W-7405-Eng-48.
ATOMISTIC SIMULATIONS OF THE PLASTICITY BEHAVIOR

OF SINGLE CRYSTAL AND POLYCRYSTALLINE METALS

Michael I. Baskes1, M. F. Horstemeyer2, and S. J. Plimpton3

1

Structure Property Relations Group

Los Alamos National Laboratory, Los Alamos, NM 87545 USA

2

Center for Materials and Engineering Sciences

Sandia National Laboratories, Livermore, CA USA

3

Center for Computation, Computers & Math

Sandia National Laboratories, Albuquerque, NM USA

baskes@lanl.gov

We examine the effects of deformation on single crystal and polycrystalline FCC

metals. We perform simple shear molecular dynamics simulations using the

Embedded Atom Method (EAM) on nickel samples ranging from 100 atoms to

100 million atoms to study yield and work hardening. It is found that the

deformation is always inhomogeneous when a free surface or grain boundary is

present. The results of the single crystal simulations are compared to data from

nano-indentation experiments, micro-indentation experiments, and small scale

torsion experiments. This comparison shows that the yield stress varies as L-0.4

over five orders of magnitude in which a length scale parameter, L, is defined by

the ratio of volume to surface area. The atomistic simulations reveal that

dislocations nucleating at free surfaces and grain boundaries are critical to causing

yielding in pristine material as observed in experiment [1, 2].

Detailed investigation shows that the grain boundaries are significantly weaker

than the bulk material and yield at a lower stress. Even so, the yield stress of the

polycrystalline samples with both low angle and high angle grain boundaries are

found to be similar and only slightly lower than the yield stress of single crystals

with the same characteristic dimensions. Reduction of geometric constraint in the

calculations results in a significant lowering of the yield stress.

The atomistic simulations and experimental data show that differences in applied

strain rate, temperature, stacking faults (several FCC materials have been

examined), deformation mode, and crystal orientation on yield and plasticity are

small compared to the size scale effect.

[1] J. W. Mitchell, Phys. Stat. Sol. (a) 135, (1993) 455.

[2] J. C. M. Li, M. A. Imam, and B. B. Rath, J. Materials Science Letters 11,

(1992) 906.
INORGANIC NANOCRYSTALS AND NANORODS: SYNTHESIS

AND BIOLOGICAL APPLICATIONS

Liberato Manna, E Scher, W Parak, D Gerion, V F Puntes, L-Shi Li

and A P Alivisatos

Department of Chemistry

University of California, Berkeley

Hilldebrandt Hall B62

Berkeley, CA 94720 USA

and Lawrence Berkeley National Laboratory,

manna@socrates.berkeley.edu

In semiconductor nanocrystals, due to confinement of the charge carriers, analogous to

aparticle-in-a-box-model, the band gap is size-dependent. Therefore the wavelength of

emission following photoexcitation can be tuned by the size of the nanocrystals. Recent

advances in the synthesis of colloidal CdSe and Co nanocrystals have been made

allowing for shape control. Nanocrystal bio-polymer conjugates hold great promise both

for biological diagnostics, where the nanocrystals can provide unique detection

signatures, and for nanotechnology, where the information content of the bio-molecule

can be harnessed for spatial patterning of nanocrystals. In materials science, assemblies

of particles have been constructed by using oligonucleotides as molecular scaffolds for

supporting oligonucleotide labeled nanocrystals. In biological research, semiconductor

nanocrystals in a range of colors have been used as fluorescent probes for cellular

imaging. Due to their reduced photobleaching properties they are especially suitable for

dynamic studies in living cells. We show that nanocrystals are actively incorporated by

living cells. The uptake is analyzed in dependence of the nanocrystals' size and charge.

Dynamic confocal microscopy images suggest, that negatively charged and almost

neutral silanized nanocrystals are endo- or phago-cytosed by living cells and arranged in

intracellular vesicular compartments.
GRAIN BOUNDARIES IN GALLIUM ARSENIDE NANOCRYSTALS

Sanjay Kodiyalam, R K Kalia, H Kikuchi, A Nakano, F Shimojo1, and P Vashishta.

Concurrent Computing Laboratory for Materials Simulations and Biological Computation

and Visualization Center, Department of Physics and Astronomy,

Department of Computer Science

Louisiana State University

Baton Rouge, LA 70803-4001 USA

1

Faculty of Integrated Arts & Sciences, Hiroshima University, Japan

sanjay@rouge.phys.lsu.edu

We have investigated structural transformation in GaAs nanocrystals using parallel

molecular dynamics (MD) simulations. Spherical and faceted nanocrystals of different

sizes are studied by suspending them in a liquid and then isothermal-isobaric MD

simulations are performed. It is found that the transformation from four-fold (zinc

blende) to six-fold (rock salt) coordination is nucleated on the nanocrystal surface and

proceeds inwards with increasing pressure. Inequivalent nucleation of the rock salt phase

at different sites on the surface leads to non-uniform deformation of the nanocrystals.

The transformation is sensitive to initial shape: spherical nanocrystals above a critical

diameter ≥ 44 Å always show grain boundaries where as faceted nanocrystals of

comparable size do not show grain boundaries in 40% of the cases. The pressure to

complete the transformation is found to increase with nanocrystal diameter and

approaches the bulk value from below. A thermodynamic explanation for this trend

based on nanocrystal-liquid interface enthalpy is attempted. Spatially resolved phonon

densities of states correlate with local structure.

This work has been supported by NSF, DOE, AFOSR, DoD-DURINT, NASA and BCVC

(Louisiana Board of Regents).
NANOFABRICATION RESEARCH AND CAPABILITIES AT

CORNELL NANOFABRICATION FACILITY

Alex Pechenik

Associate Director of CNF.

CNF, Knight Lab

Cornell University

Ithaca, NY 14853-5403 USA

Pechenik@cnf.cornell.edu

Cornell Nanofabrication Facility (CNF) is a National user facility – a part of the National

Nanofabrication User Network (NNUN) funded by a grant from NSF. The goal of CNF

and NNUN is to facilitate and support research of others from all around the Nation.

With nearly $30M worth of equipment and 20 members of technical support staff, skillful

in any kind of Nanofabrication techniques and processes, CNF services a rapidly growing

U.S.-wide research community. This year, nearly 700 users performed Nanofabricationrelated projects at CNF. Most of these projects required training, assistance, and,

occasionally, design and process development expertise from the CNF technical staff.

This talk will give a brief overview of CNF facilities, modes of interaction with outside

users, and give examples of some recent projects performed here. Projects from the

fields of chemistry, biology, electronics, mechanics, optoelectronics, and nanostructure

physics will be presented with the emphasis on the unique nanofabrication capabilities

that are available to outside users at CNF. The unique CNF needs in materials and

process simulation at the nanoscale will be addressed, as well.
PROCESS-STRUCTURE-PROPERTY RELATIONSHIPS OF

POLYMERIC BIOMATERIALS

Michael Jaffe

Department of Biomedical Engineering

 New Jersey Institute of Technology

 University Heights

 Newark, New Jersey 07102-1982 USA

Jaffe@ADM.NJIT.EDU

The Process-Structure-Property-Performance paradigm of material science is well known

and is routinely used to define and optimize synthetic polymers for specific applications.

One of the underlying themes of the Medical Device Concept Laboratories is to apply

this paradigm to the emerging field of bioerodable, polymeric biomaterials. Our specific

objectives are:

Understanding the origins of the biological and material properties exhibited

by these materials as function of their chemistry, morphology and surface

characteristics

Quantifying the effects of processing on the development of structural features

Developing characterization techniques relevant to in-vivo use

The combinatorial library of desaminotyrosyl polyarylates developed by Professor

Joachim Kohn of Rutgers University, is being investigated as a model system. Selected

library polymers are melt formed into uniform fibers and films defining a range of

structural and performance characteristics. Existing thermal analysis, microscopic and

spectroscopic techniques are utilized as platforms for developing biorelevant data sets,

capable of extrapolation to in-vivo performance prediction. The influence of structural

features, from the nanoscale through the macroscale, on biological performance is being

investigated.

Results to date indicate that the Kohn library is extraordinarily rich in structural features

and performance options. It was found that some library polymers form novel,

mesogenic nanostructures of interest to the polymer physics community independent of

the impact of this structure on biological activity. Cell culture studies are currently

underway to quantify the effects of this novel morphology on cellular growth. The impact

of controlled mechanical properties and dimensional stability on the efficacy of these

materials as ACL repair scaffolds is being investigated in collaboration with Professor M.

Dunn of the RWJ Medical School.
SHORT AND INTERMEDIATE RANGE ORDER IN DISORDERED

GexSe1-x SYSTEMS

Carlo Massobrio

Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS

Rue du Loess

F-67037 Strasbourg, France

Carlo.Massobrio@ipms.u-strasbg.fr

Interest in disordered GexSe1-x systems is motivated by the peculiar structural changes

exhibited over the whole compositional range, which reflect variations in the nature of

bonding. On the Se rich side (x=0.2, GeSe4 and x=0.33, GeSe2), intermediate range order

(IRO) which establishes on length scales significantly more extended than nearest

neighbor distances gives rise to the presence of a first sharp diffraction peak (FSDP) in

the total neutron structure factor. First principle molecular dynamics studies have shown

that liquid GeSe4 is a chemically ordered system [1], i.e. the number of heteropolar bonds

is maximized. On the other hand, in liquid GeSe2 the chemical order is broken due the

presence of miscoordinated atoms and homopolar bonds which coexist with GeSe4

tetrahedra[2]. The existence of homopolar Ge-Ge bonds for this composition has also

been recently firmly established for amorphous GeSe2.

To highlight the intimate relationship between bonding and intermediate range order in

disordered network-forming systems, liquid GeSe2 has been investigated by adopting two

distinct functionals for exchange and correlation within density functional theory. It was

found that a generalized gradient approximation (GGA) is required to reproduce a FSDP

in the total structure factor, while, when the local density approximation (LDA) is used,

the FSDP is absent.

An analysis of the bonding configurations indicates that liquid GeSe2 is a defective

network consisting of predominant Ge-centered tetrahedral units but Ge- and Se-centered

triads and homopolar bonds occur in nonnegligible amounts. The number of Ge-Ge

homopolar bonds and of ordered fourfold rings compare favorably with experimental

estimates. Chemical disorder manifests through an important percentage of Se-rich odd

membered rings. We characterized the intermediate range order by studying the relation

between real-space distances and the FSDP. We found that this feature appears when

correlations beyond 5Å are accounted for. The evaluation of bond lifetimes reflect the

higher stability of Ge-Se bonds with respect to homopolar bonds, consistent with the

predominance of tetrahedral units [5].

[1] M. J. Haye, C. Massobrio, A. Pasquarello, A. de Vita, S. W. de Leeuw, R. Car, Phys

Rev B 58, 14661 (1998).

[2] C. Massobrio, A. Pasquarello, R. Car, Phys Rev Lett 80, 2342 (1998).

[3] I. Petri, P. S. Salmon, H. F. Fischer, Phys Rev Lett 84, 2413 (2000).

[4] C. Massobrio, A. Pasquarello, R. Car, J Am Chem Soc 121, 2943 (1999).

[5] C. Massobrio, A. Pasquarello, R. Car, Phys Rev B 64, 44205 (2001).
NANOSCALE INHOMOGENEITIES IN MULTICOMPONENT

OXIDE GLASSES: MOLECULAR DYNAMICS SIMULATION

STUDY

Hiroshi Iyetomi, T Hakata, and M Misawa1

Department of Physics, Faculty of Science

Niigata University

Ikarashi, Niigata 950-2181 Japan

1

Department of Chemistry, Niigata University

Ikarashi, Niigata 950-2181, Japan

hiyetomi@sc.niigata-u.ac.jp

We present results of molecular dynamics simulations on a wide variety of

multicomponent network-forming glasses, i.e., oxide glasses with doped alkali oxides

such as Na/Si/O, Li/Si/O, and Na/B/O. The simulations are based on the Born-MayerHuggins potentials totally characterized by the charges and sizes of ions. Such a simple

model is able to account for essential features of the glassy networks modified by alkali

ions. It is one of central issues how the network-modifier cations are distributed in the

glasses. The same method[1] as used to identify Ag clusters in Ag/Ge/Se glasses is

applied to the multicomponent glasses to address that issue. We define clusters of the

alkali modifiers and then calculate their size distribution. The clustering tendency in each

glass is discussed in reference to the cluster-size distribution in a corresponding system

with randomly distributed particles. The Na ions embedded in the glassy SiO2 matrix

show clustering behavior similar to that of Ag in g-GeSe2, while no clustering of the Na

ions in g-B2O3 at all. Many glass systems show metastable immiscibility in certain

compositional range. The immiscibility behavior of alkali silicate glasses clearly depends

on the strength of the Coulomb interaction between oxygen and alkali ions: smaller

alkalis show a greater tendency to phase separation than larger alkali ions. Comparison

of the clustering behavior between Na/Si/O and Li/Si/O glasses accommodates the the

phase separation tendency. Alkali silicate glasses are inhomogeneous on nanoscale even

outside the compositional range of immiscibility although those have been regarded as

homogeneous. Relationship of the clustering nature to the dynamical properties in the

glasses is also discussed.

[1] H. Iyetomi, P. Vashishta, and R. K. Kalia, J. Non-Cryst. Solids, vol. 262, pp. 135-142

(2000).
"NANO" AND "BIO" AT THE DEPARTMENT OF ENERGY

Dale Koelling

Division of Materials Sciences

GTN, ER-132 U.S. Department of Energy

19901 Germantown Road

Germantown, MD 20874-1219 USA

Dale.Koelling@science.doe.gov

The two prefixes "nano" and "bio" are generating exciting possibilities within the

materials community. I will give a provincial view (from Basic Energy Sciences) of the

response within the Department of Energy. Although DOE is a large supporter of very

wide-ranging scientific research, it is still a mission-oriented agency. Within this context,

one defines the scope and opportunities of these new emphasis. However, I claim

absolutely NO clairvoyance!
DIRECTED ASSEMBLY OF FUNCTIONAL

NANOSTRUCTURES

Richard W. Siegel

Materials Science & Engineering Deptartment

Rensselaer Polytechnic Institute

110 8th St.Troy

NY 12180 USA

rwsiegel@rpi.edu

The past decade has seen explosive growth worldwide in the synthesis and study of a

wide range of nanostructured materials, the substance of nanotechnology. An

overview of nanoscience and nanotechnology and their relationship to novel

functional materials assembled from nanoscale building blocks will be presented

within the framework of the 2001 United States National Nanotechnology Initiative

and our new National Science Foundation Nanoscale Science and Engineering Center

for Directed Assembly of Nanostructures at Rensselaer. Several examples from our

recent research results will be presented including investigations of functional

nanocomposites that could find use in a variety of structural, electrical, and

biomedical applications.
NANOMETRIC ASPECTS OF ENERGETIC CRYSTAL

PROPERTIES/TESTING

Ronald W. Armstrong

Senior Scientist, AFRL/MNME

Eglin Air Force Base, FL 32542-5910 USA

ronald.armstrong2@eglin.af.mil

Energetic crystals exhibit an interesting combination of mechanical properties: being

elastically soft (because of their molecular/hydrogen bonding); plastically hard (because

of the mutual interference to dislocation movement of adjacent interposed molecules in

low symmetry crystal lattices); and brittle (because of relatively low, anisotropic, surface

energies)1. The large displacement vectors of dislocations lead to low dislocation

densities in solution-grown crystals that are predicted on a continuum mechanics

comparison of volumetric elastic strain energy versus substituted surface free energy to

contain “worm holes” running along the cores of the dislocation lines --- at larger hole

diameters than apply for the smaller nanometric dimensions at which the surface energy

and volume free energies are equivalent. A continuous indentation hardness stress-strain

basis has been developed for assessing the combined elastic/plastic/cracking behaviors of

energetic crystals in comparison with those behaviors of other crystal structure types 2 ---

and the method necessarily involves nanometric-scale force/displacement measurements

for assessing the connected behaviors. In particular, crystal size dependent pile-ups of

only a few dislocations are predicted to be involved in the production of “hot spots”

associated with cracking and the initiation of chemical decomposition. Smaller crystals

are known at micrometer dimensions to be less sensitive to impact initiation, consistent

with greater strength levels occurring for finer microstructures. Such model

consideration shows that energetic crystals are especially susceptible to hot spot

development on the basis of their combined [crack initiation/thermal conductivity]

properties --- relating also to the general property of shear banding in structural materials.

[1] R.W. Armstrong and W.L. Elban, “Dislocation characteristics in energetic crystals”,

CP505, Shock Compression of Condensed Matter – 1999, edited by M.D. Furnish, L.C.

Chhabildas, and R.S. Hixson, 2000, American Institute of Physics, NY, pp. 723-726.

[2] R.W. Armstrong, H.L. Ammon, W.L. Elban, and D.H. Tsai, “Investigation of hot spot

characteristics in energetic crystals”, invited paper for a special “Energetic Materials”

issue of Thermochimica Acta, 6871 (2001) 1-11, in print.
ADAPTIVE ABERRATION CORRECTION IN CONFOCAL

MICROSCOPY

Tony Wilson, M. A. A. Neil and M. J. Booth

Department of Engineering Science

University of Oxford

Parks Road Oxford

OX1 3PJ UK

tony.wilson@eng.ox.ac.uk

The confocal microscope is becoming an instrument of choice in many laboratories in

both the life and physical sciences since it's optical sectioning property permits the

images of volume structures to be rendered in three-dimensions. In order to achieve this

volume rendering a series of through-focus images must be recorded at different focal

depths within the specimen. An inevitable consequence of this is that aberrations are

unavoidably introduced. Aberrations, due to refractive index mismatch are further

introduced by using, for example, an oil immersion objective to image a watery

specimen. In order to overcome this fundamental problem we will describe an adaptive

optics approach in which a novel wavefront sensor is used both to measure the

aberrations introduced and to provide control signals to an adaptive element for

correction. The system works in closed loop and permits diffraction limited resolution to

be restored at depth. Examples will be shown from both the biological sciences and the

physical sciences where the system will be applied to the reading of three dimensional

optical memory materials.
THE USE OF ‘EXTREMOPHILE’ PROTEINS IN BIO-NANOTECHNOLOGY

Jonathan Trent

NASA Ames Research Center

Mail Stop 239-15

Moffett Field, CA 94035 USA

jtrent@mail.arc.nasa.gov

The kinds of “weird effects” that were once Feynman and are now you and me and the

whole biosphere are ultimately dependent on the physics and chemistry going on at the

nanometer (molecular) scale. As the nano-scale becomes a focus for engineering, a role

for ‘bio-nano-technology’ is emerging to address fundamental engineering problems on

that scale. We have been exploring the potential of using a class of proteins known as

‘heat shock proteins’ (specifically HSP60s) for producing nano-structures with industrial

applications. This class of proteins self-assemble into double-ring structures with seven,

eight, or nine protein subunits per ring. Through the use of HSP60 genes from

‘extremophiles’ (i.e., organisms living in extreme environments—near-boiling

temperatures and at pH 2.0), we are developing simple and effective methods for

obtaining industrial quantities of these proteins. By using tools of crystallography and

molecular biology, we are exploring the range of structures that can be created using the

HSP60 double rings as building blocks.
THE CONVERGENCE OF BIOLOGY AND NANOSCIENCE: AN

OPPORTUNITY FOR MOLECULAR DEVICES BUILT WITH

BIOLOGICAL MOLECULES

Stephen Lee

Biomedical Engineering Center, Chemical Engineering

Cellular and Molecular Biology

317 Bevis Hall,1080 Carmack Road

Columbus, OH 43210 USA

lee@bme.ohio-state.edu

Nanoscience and biology are discrete disciplines that contribute substantially to each

other. Their intersection creates an opportunityfor hybrid nanodevices, with nanoscience

providing a pallet of precise(primarily) structural nanomaterials, and biology providing a

vast menu of functional nanostructures. Successful hybrid devices (called nanobiological,

nanobiotechnological devices or biologic nanodevices) have common features and their

construction can be codified into a set of steps applicable to a broad sweep of devices.

Initial applications of the approach have been predominantly biomedical, but

nanobiological devices will not be limited to those applications in the long run, and

hybrid devices will ultimately be applicable to many tasks of importance. Emerging and

established engineering and biological paradigms inform device design, synthesis and

use, and engineering of their components, which should allow broad commercialization

of nanotechnology. Nanobiotechnology allows construction of commercial quantities of

nanodevices without recourse to self-replication, avoiding an oft-sited concern about the

safety of nanotechnology. Continued commitment to nanoscience, biology and the

technology and areas at their interface is essential to assure the legitimate human

aspiration for a better, more sustainable world.
PHAGE AS ENGINEERED SELF-REPLICATING SELFASSEMBLING SYSTEM FOR NANOFABRICATION OF

BIOSELECTIVE SENSORS

Valery A. Petrenko, A M Samoylov and V J Vodyanoy

College of Veterinary Medicine

264 Greene Hall

Auburn University

Auburn, Alabama 36849-5519

petreva@vetmed.auburn.edu

Filamentous phage, such as M13, f1 and fd, are thread-shaped bacterial viruses. Their

outer coat is composed of thousands of 50-residue a-helical subunits of the major coat

protein pVIII, which overlap one another to form a tube encasing the viral DNA. We

have shown that filamentous phage can serve as a scaffold, able to form on its surface an

indefinite number of potential antigen-binding sites by displaying random peptides fused

to major coat protein pVIII. We constructed libraries with random peptides fused to

pVIII in various formats, and selected phages that act as substitute antibodies specific for

a panel of test antigens and model "threat agents" (Petrenko, 1996, 2000; Romanov,

2001). Because the viral carrier is infective, phage borne bio-selective probes can be

cloned individually; thus, either whole libraries or individual clones can be propagated

indefinitely without needs of their chemical synthesis or reconstructing (Smith &

Petrenko, 1997). can bind biological agents and, as a part of an analytical platform,

generates a detectable signal. As elements of field-use detectors, they are superior to

monoclonal antibodies, since they are inexpensive, highly specific and strong binders,

resistant to unfavorable environmental conditions.

This work is a first demonstration of the use of landscape phages as bio-selective ligands

in biosensors. As substitute antibodies phages demonstrate many features (high affinity,

field stability, low cost etc.), which allow considering them as prospective ligands in a

new generation of sensors for food safety control and environmental in-a-real-time

monitoring.

[1] Petrenko V.A., Smith G.P., Gong X. and Quinn T. (1996) Protein Engineering, V.9,

N9, p.797-801

[2] Smith G.P. and Petrenko V.A. (1997) Chemical Reviews, V.97, N2, p. 391-410.

[3] Petrenko V.A. and Smith G.P. (2000) Protein Engineering, V.13, N8, p.589-592.

[4] Romanov V.I., Durand D.E. and Petrenko V.A. (2001) The Prostate (2001),V.47,

p.239-251.

This work was supported by ARO grant DAAD19-01-10454 (VP), DARPA grant

MDA972-00-1-0011 (VV) and Detection and Food Safety Center of Auburn University.
PATTERN FORMATION AND CELL SIGNALING AT AN

INTERMEMBRANE SYNAPSE

Jay T. Groves

Department of Chemistry

105 Lewis Hall

University of California, Berkeley

Berkeley, CA 94720-1460 USA

JTGroves@lbl.gov

Spatial organization of proteins is an emerging theme of broad significance in cell

recognition and signal transduction. Cells from the immune system and nervous system,

among others, engage target cells through highly organized patterns of proteins that

assemble at the intercellular synapse. Recent studies have revealed dynamic patterns

within the immunological synapses formed when either T- or NK-cells engage their

respective target cells. Though still controversial, there is mounting evidence indicating

that specific synaptic patterns correlate with cellular activation. We are exploring the

physical mechanisms behind synaptic pattern formation at intermembrane junctions

in an effort to elucidate their role in cell recognition and signaling.

The fundamental problem we address is the collective interaction of populations of

receptors and ligands in apposing lipid bilayer membranes. The membrane introduces a

fluctuating two-dimensional reaction environment in which topographical constraints and

restricted component access strongly influence receptor binding and spatial organization.

From theoretical studies, we have found that these membrane constraints modulate the

collective receptor ligand binding such that patterns on the nanometer and micrometer

scale can emerge spontaneously. Our theoretical predictions have proven to correspond

with observations of synaptic patterns in living T-cells.

In order to address this problem experimentally, we have initiated development of a

totally reconstituted inter-membrane junction between a supported membrane and a

second membrane patch, which is deposited from a giant vesicle. Incorporation of

different fluorescent probe lipids into each of the two membranes enables a variety of

fluorescence imaging capabilities which we employ to obtain both lateral and

topographical information about the junction. We have demonstrated that fluorescence

resonance energy transfer (FRET) between the two membranes when they are closely

apposed (< 5 nm) leaves a footprint, which maps the contact zone. Larger topographical

features can be observed when the membrane system is supported on an oxidized silicon

wafer. Near-field interference effects set up optical standing waves that provide contour

mapping of the membrane topography with resolution in the nanometer range extending

over a micron from the surface. Topographical patterns are a critical feature of cell-cell

contacts that are not easily measured by current real-time imaging techniques. This new

membrane system and combined imaging strategies will form an important component

of our experimental platform for further reconstitution and analysis of inter-membrane

synapse formation.
PHYSICAL OBSERVATION / COMPUTATIONAL STRUCTURAL

INTERFACES OF INFO-BIO-NANO TECHNOLOGY

Ken L Reifsnider and X. Huang

Department of Engineering Science and Mechanics

Materials Response Group

Virginia Polytechnic Institute and State University

Blacksburg, Virginia 24061 USA

mrl@vt.edu

In this paper, we will be concerned with interfaces that have high density gradients

over large transition distances. First, we will consider real material interfaces, for

situations that involve biological systems and for situations that involve functional

(engineering) material systems. Second, we will be concerned with virtual interfaces

between the bio-, nano-, and information technologies, especially the manner in

which real information is used to conceptualize multiphysics phenomena at multi

scales of geometry to describe and predict system behavior.

We will begin with physical interfaces in the field of biotechnology. Two examples will

be considered. The first is the composite interfaces formed in the complex systems used

for tissue scaffolding, and the relationship of the constituents to the global function of the

tissue. The second is the interface between prosthetic implants and human bone, with

specific reference to hip implants. Specific attention will be paid to the situation wherein

the bone is induced to “grow into” the surface of the prosthetic. An attempt will be made

to define the interface details at the nano-scale which influence / control global behavior,

and to define the multi-physics phenomena associated with those details.

We will then extend the multi-physics concept to composite interfaces in fuel cells, in

which the system function is defined by the nano-details of the local geometry, the local

physics of the electro-chemistry, the local mechanics of heat and energy management,

and the chemistry of the fuels and oxidants. We will show similarities with the biosystem that result from consideration of nano-details, and illustrate the analogy with a set

of multi-scale (in time and geometry) solutions to the equation set that controls the

performance of the fuel cells.

Finally, we will address the question of information in these problems, especially the

question of how to identify physical measureables (observables) at the nano-level that can

be used as inputs to the equation sets that describe nano-phenomena and behavior. A

discrete element simulation approach is used to investigate the deformation

characteristics of an interface between two porous materials. A boundary value problem

is formulated on a finite size element across the interface and the effective interface

properties are calculated through a novel averaging process. A particular aspect of special

interest will be the discussion of micro- or nano-analysis simulation methods that can be

used for porous nano-structures that do not have repeating geometric units, and therefore

cannot be correctly approached with the usual homogenization methods. Examples of

this approach will be illustrated for a distributed, random porous material nano-structure

and compared to available estimates from the literature.
HIGH RESOLUTION 3D VISUALIZATION OF

ATHEROSCLEROSIS

Hua Jin1, K Ham2, S Thiam3, J Robinson3, R Agban3, I Warner3,

L Butler3 and R Kurtz1

1 Department of Physics & Astronomy

 2 Center for Advanced Microstructures and Devices

3 Department of Chemistry

Louisiana State University

Baton Rouge, LA 70803, USA

hjin1@lsu.edu

Atherosclerosis is the leading cause of morbidity and mortality in the United States and

other industrialized countries. Several methods are currently used to detect and quantitate

atherosclerosis, such as angiography, ultrasonography, computed tomography and

magnetic resonance imaging. The resolutions of these clinical imaging methods are in the

orders of millimeters or sub-millimeters. High resolution imaging of atherosclerosis is

necessary for studying the morphological changes of diseased artery, especially for small

sized plaques, which may be formed in the early stage of atherosclerosis. In this paper,

we present morphologies of atherosclerosis by using synchrotron radiation computed

microtomography with a spatial resolution of several microns. We studied 6

atherosclerosis samples from three patients aged from 51 to 70 in their native forms, and

their corresponding bypass arteries. Atherosclerotic lesions such as the plaques were

identified in both native and bypass samples. Cross section and 3D visualization of the

atherosclerosis in the x-, y- and z- direction will be displayed. 3D volumetric images of

deposited plaques will be rendered. The morphological differences among the samples

with one another were recognized and the extent of the atherosclerotic plaque will be

defined.
DYNAMICAL PROCESSES IN GREEN FLUORESCENT PROTEIN

C Liebig1, William Dennis 1, S Kirkpatrick2, R Naik2, M Stone2

1

Department of Physics and Astronomy

University of Georgia, Athens, GA 30602 USA

2

 Materials and Manufacturing Directorate

Air Force Research Laboratory

Wright-Patterson Air Force Base, Ohio 45433 USA

bill@hal.physast.uga.edu

Green fluorescent protein (GFP) extracted from the bioluminescent jellyfish Aequorea

Victoria[1] and its mutants form a nanoscale cylindrical (3 x 5 nm) structure in which the

chromophore is embedded in the center of the cylinder. These proteins have been shown

to exhibit desirable linear and nonlinear optical properties[2]. In this paper we use time

resolved linear and nonlinear spectroscopies to investigate dynamical processes in

fluorescent proteins in both aqueous solution and an organic polymer matrix.

Experimental results were analyzed in terms of a Brownian oscillator model[3] and by

comparison to computer simulations.

[1] M. Chalfie, G. Euskirchen, W. W. Ward and D. C. Prasher, Science 263 (1994) 802.

[2] Sean M. Kirkpatrick, Rajesh R. Naik, Morley O. Stone, J. Phys. Chem. B 105 (2001)

2867.

[3] S. Mukamel, Nonlinear Optical Spectroscopy, (Oxford University Press, New York,

1995) pp. 227
FRICTIONAL PROPERTIES OF SELF-ASSEMBLED

MONOLAYERS

Gary S. Grest, M Chandross, B Park, and M Stevens

Materials & Process Computation & Modelling

Sandia National Laboratory

Albuquerque, NM 87185-1411

 gsgrest@sandia.gov

Results from molecular dynamics simulations of alkylsilane monolayers on silica and

alkylthiol monolayers on gold will be presented. The dependence of the normal forces

between surfaces containing self-assembled monolayers will be studied for various chain

lengths ranging from 6 to 18 hydrocarbons and for different end-groups. The results will

be compared to experiments from atomic and interfacial force microscopy. The

frictional forces between the surfaces are studied at normal loads of 0.2 and 2 GPa for

velocities ranging from 0.02 to 20.0 m/s. We find that for well-ordered monolayers there

is stick/slip motion at all loads and velocities, and that the dependence on velocity and

chain length is weak. As all experimental systems contain defects, we have also

performed shear simulations in which defects have been added to the monolayers. The

defects include the removal of randomly selected chains from the crystalline surface, as

well as the inherent disorder in chains bonded to an amorphous silica surface. We find

that in all cases the introduction of defects destroys the stick/slip motion. We have also

investigated possible finite size effects in our simulations by varying the surface area by a

factor of sixteen and find that larger system sizes result only in decreased noise.
CRACKS AND CRAZES: FROM MOLECULAR SIMULATIONS TO

THE MACROSCOPIC TOUGHNESS OF POLYMERS

Mark Owen Robbins, Jörg Rottler and Sandra Barsky

Department of Physics & Astronomy

Johns Hopkins University

Baltimore MD 21218-2686 USA

mr@java.pha.jhu.edu

Understanding the molecular origins of macroscopic mechanical properties such as the

fracture toughness Gc is a fundamental scientific challenge. In tough materials, the work

Gc required to propagate a crack through a unit area is 3 to 4 orders of magnitude higher

than the equilibrium interfacial free energy Geq of the crack surfaces. Efforts to calculate

this large toughness enhancement have been frustrated, because phenomena on many

length scales must be treated simultaneously. In the case of glassy polymers considered

here, the toughness is mainly due [1] to the formation of an intriguing craze structure

around the crack tip. Polymer chains (nm in diameter) are bundled into a dense network

of fine fibrils (5-30 nm in diameter) that are separated by voids. Crazes can grow up to 50

mm in width before they break.

In this paper, we bridge length scales by combining an MD calculation of model

polymers [2] with a continuum fracture model [3] for the onset of crack propagation to

predict the macroscopic toughness of glassy polymers. Key input parameters for the

fracture mechanics model are obtained from simulations of the mechanical properties of

the polymer in the different regions illustrated in Fig. 1. Craze widening proceeds by

drawing fibrils separated by a characteristic spacing D0 out of the dense polymer glass.

(Drawing occurs within a narrow “active zone” at constant drawing stress S. The volume

of the material is increased by a constant extension ratio l, which is determined by the

entanglement length [1]. The toughness can be obtained from the work performed on the

polymer during crazing, which is S times the increase in width of the crazed region from

an initial value of d/l to a final width d.

The final width d of the craze is limited by the stress concentration near the crack tip.

This diverges as d1/2 [3] and when the stress reaches a maximum value Smax the fibrils fail

and the crack tip propagates through the craze. The magnitude of the stress concentration

was determined from the elastic properties of the craze (Fig. 1B), and Smax was obtained

from the stress where fibrils fail through pullout or chain scission. Our results for the

final craze width and the toughness enhancement are in good agreement with

experimental values. A key parameter is the ratio of the length of the chains to the

entanglement length. When this ratio is less than about 2, crazes do not form and the

toughness is small. As the ratio rises above 2, Gc/Geq rises rapidly. Gc/Geq saturates at

2000 to 5000 for long chains because they break rather than pulling out when the craze

fails.

[1] E. J. Kramer and L. L. Berger, Advances in Polymer Sci. 91, 1 (1990).

[2] K. Kremer and G. S. Grest, J. Chem. Phys. 92, 5057 (1990).

[3] H. R. Brown, Macromolecules 6, 2752 (1991).
UNITED-ATOM MODELS OF POLYMERIC MATERIALS: A

UNITED ATOM MODEL OF POLYETHYLENE WITH THE

MODIFIED EMBEDDED ATOM METHOD

Steven M. Valone, M I Baskes

Materials Science and Technology Division and Theoretical Division,

 Los Alamos National Laboratory,

Los Alamos, NM 87545

smv@lanl.gov

Nanotechnology developments are driving a need for a greatly improved understanding

of polymeric material behavior. The behavioral range of interest encompasses polymerinorganic interfaces, as well as bulk material behavior. Among the major issues in bulk

materials is the influence of environmental factors such as solvent quality, pH and

dielectric properties. Such influence virtually electron density of the polymer and any

solvent be part of a model of these materials. Current polymer model typically neglect

any explicit modeling of the valence electron density. The modified embedded atom

method (MEAM) does explicitly model valence electron density. This presents the

possibility of a unique modeling approach to polymer-polymer and polymer-solvent

interactions. We present a united-atom model of polyethylene as a simple illustration of

this modeling approach. Two valence-electron density parameters naturally lend

themselves to regulating the interaction of a polymer chain with other chains and solvent

molecules. Through these parameters, the polymer tack and folding behavior as a

function of environmental variables. The regulation of polymer tack and folding without

solvents will be illustrated here.

 Work supported by the US Department of Energy under contract W-7405-ENG-36 to the

University of California.
YIELDING PMMA - A SIMULATION STUDY

Thomas Soddemann and M O Robbins

Department of Physics & Astronomy

Johns Hopkins University

Bloomberg 317, 3400 N Charles Street

Baltimore, MD 21218-2686 USA

soddeman@pha.jhu.edu

Thermotropic materials have important applications in industry and are both used pure or

in a composite. Mechanical response to deformation of those materials is of great interest,

e.g. to be able to make predictions about fatique due to constant deformation. Previous

computer simulations by J. Rottler etal. have shown that model systems composed of

beads connected by springs exhibit similar behavior to that observed in experiments.

PMMA is a real world material with a simple chemical structure which is well suited to

be investigated in respect to its response to deformation, the more so as it has been well

studied in experiments. Two different force fields have been applied in this study, the

Polymer Consistent Force Field by MSI treats all atoms, while Okada's et al. forcefield

neglects hydrogens and uses united atoms instead. First the glass transition of

temperatures of PMMA of both force fields have been compared to each other in order to

validate their use. Later the viscoelastic behavior, yield points and stresses produced in

simulation have been put into relation with experimental data.
AN OVERVIEW OF MAGNETIC NANO-PINNING AT TEXAS A&M

UNIVERSITY

Malcolm J. Andrews

Department of Mechanical Engineering,

 Texas A&M University

College Station, TX 77845 USA

mandrews@mengr.tamu.edu

We are exploring the use of high temperature superconductors as nano-pinning devices

for magnetic flux. This talk presents an overview of the various materials

science/magnetic flux/positioning/simulation research being performed at Texas A&M

University to explore and characterize various magnetic flux arrangements. Since pinning

in HTSC's takes place on the nanoscale, pinned vorices offer a variety of opportunities

for electronic nanoscale technologies such as information storage. A review will also be

given of progress and the challenges that lay ahead.
MONTE CARLO SIMULATION ON THE RKKY INTERACTIONS

OF Co-DOPED ZnO FILM

Abraham F. Jalbout 1,2,3 S Fernandez 3 and H Chen 1

1 Department of Chemistry, University of New Orleans,

New Orleans, LA 70148 USA

2 Department of Physics, Dillard University,

New Orleans, LA 70112 USA

3 Department of Chemistry, Loyola University,

New Orleans, LA 70118 USA

AJalbout@ejmaps.org

Monte Carlo simulations using a three-dimensional lattice model studied the RKKY

indirect exchange interaction of doped magnetic Co ions in ZnO films. The results of the

calculations show that the RKKY interaction in Co-Doped ZnO is long-ranged and its

magnitude is proportional to R-1. The sign oscillates with a frequency that depends on the

carrier’s concentration. The long-distance sum of the RKKY indirect exchange energies

is positive indicating that these materials are ferromagnetic, in direct correlation with

previously reported results.
QUANTUM ENERGY TRANSPORT IN NANOSCALE SYSTEMS

Michael R. Geller and K R Patton

Department of Physics and Astronomy

University of Georgia

 Athens, GA 30602 USA

mgeller@hal.physast.uga.edu

We give an overview of our recent theoretical investigations of thermal transport in

mesoscopic and nanoscale systems. Recently, a quantization of the thermal conductance

in freely suspended one-dimensional dielectric wires was observed [1], analogous to the

well-known electrical conductance quantization in one-dimensional mesoscopic

conductors. In the present work we consider mesoscopic thermal transport through a wire

or weak link in the limit where the phonon transmission probability through the wire is

small and the thermal conductance is much less than the quantized value [2]. We find that

the thermal current is determined by a product of the local vibrational spectral densities

of the two bodies, and derive a general expression for the energy flux that is a thermal

analog of the well-known formula for the electrical current through a tunneling barrier.

[1] K. Schwab, E. A. Henriksen, J. M. Worlock and M. L. Roukes, Nature 404, 974

(2000).

[2] K. R. Patton and M. R. Geller, Phys. Rev. B 64, 155320 (2001).
PHONONS IN A NANOPARTICLE MECHANICALLY COUPLED

TO THE ENVIRONMENT

Kelly R. Patton and M R Geller

Department of Physics and Astronomy

University of Georgia

 Athens, GA 30602 USA

kpatton@hal.physast.uga.edu

The discrete nature of the vibrational modes of an isolated nanometer-scale solid

dramatically modifies its low-energy electron and phonon dynamics from that of a bulk

crystal. However, nanocrystals are usually coupled, even if only weakly so, to an

environment consisting of other nanocrystals, a support matrix, or a solid substrate, and

this environmental interaction can dominate the vibrational properties at low frequencies.

We will discuss our recent investigation the modification of the vibrational modes of an

isolated spherical nanoparticle caused by a weak mechanical coupling to a semi-infinite

solid substrate. As a probe of the modified nanoparticle phonon spectrum, we consider an

electron in a localized impurity state in the nanoparticle, and calculate the rate of lowenergy nonradiative energy relaxation provided by the substrate interaction.
CARBON NANOTUBES IN NANOELECTRONICS AND SENSOR

DEVELOPMENT

Meyya Meyyappan

NASA Ames Research Center

Mail Stop 229-3, Building 229,Room 214

Moffett Field CA 94035 USA

meyya@orbit.arc.nasa.gov

Carbon nanotubes (CNT) exhibit extraordinary mechanical properties and unique

electronic properties and thus are being investigated widely for applications in

nanoelectronics, sensors, composites, nanoelectromechanical systems to name a few. We

have focused on controlled growth of CNTs using CVD for applications in device and

sensor fabrication. Both p- and n- type CMOS transistors using CNTs have been

fabricated and used to develop an inverter -a building block towards future nanotube

based logic circuits. We have also been developing a biosensor based on CNTs for

cancer diagnostics. The tasks on this development call for growth of vertically aligned

nanotube arrays, functionalization of this array with DNA or PNA probe molecules, and

electrochemical signal generation due to hybridization events. All these have been

successfully accomplished and this talk will provide an overview of the research above.

In addition, computational nanotechnology issues at every stage would be identified

which can complement the experimental work by providing insight into mechanisms.

Contributions from Alan Cassell, Bin Chen, Lance Delzeit, Jie Han, Jun Li,

Cattien Nguyen, Deepak Srivastava, and Ramsey Stevens are acknowledged.
BUILDING ORGANIZED ARCHITECTURES WITH CARBON

NANOTUBES

Pulickel M. Ajayan

Department of Materials Science and Engineering

Rensselaer Polytechnic Institute

Troy, New York 12180-3590, U.S.A.

ajayan@rpi.edu

This talk will focus on the directed assembly of multiwalled carbon nanotubes on

planar substrates into highly organized structures that include vertically and

horizontally oriented arrays, ordered fibers and porous membranes. The concept of

growing such architectures is based on growth selectivity on certain surfaces

compared to others. Selective placement of ordered nanotube arrays is achieved on

patterned templates prepared by lithography or oxide templates with well-defined

pores. Growth of nanotubes is achieved by chemical vapor deposition (CVD) using

hydrocarbon precursors and vapor phase catalyst delivery. The new technique

developed in our laboratory allows enormous flexibility in building a large number of

complex structures based on nanotube building units. The understanding of the early

stages of nanotube film growth during this CVD process will be discussed. It is

observed that there are select pathways during the growth process of nanotube films

on substrates, influencing the final morphology of the films developed, and these

pathways can be tailored by tuning the catalyst concentration in the vapor phase. We

will also discuss some of our recent efforts in creating nanotube junctions selectively

and controllably.
EFFECTS OF STRUCTURAL DEFORMATION AND CHIRALITY

ON ELECTRON TRANSPORT IN CARBON NANOTUBES

Alexei Svizhenko, A Maiti and M.P Anantram

NASA Ames Research Center

Moffett Field, CA 94035-1000 USA

Svizhenk@nas.nasa.gov

Recent experiments (Ref. 1) showed that the conductance of a nanotube suspended

between two leads decreased by two orders of magnitude upon deformation with an

AFM tip. In this work we provide a theoretical explanation for the conductance drop

observed. Atomistic simulations using a combination of classical forcefield and

Density-Functional-Theory (DFT) show that carbon atoms remain essentially sp2

coordinated in either bent tubes or tubes pushed by an atomically sharp AFM tip.

Subsequent non-orthogonal tight-binding Green's function calculations reveal that for

arm- chair tubes there is no significant drop in conductance, while for zigzag tubes

the conductance can drop by several orders of magnitude in AFM-pushed tubes. We

conclude that the effect can be attributed to simple stretching of the tube concurrent

with the tip deformation, which opens up an energy gap at the Fermi surface

throughout the tube.

[1] T. W. Tombler et al., Nature, vol. 405, p. 769 (2000)
AB-INITIO MOLECULAR DYNAMICS STUDIES OF

NANOSTRUCTURES AND BIOMOLECULES

Roberto Car

Department of Chemistry

107 Hoyt Laboratory, Princeton University

Princeton, NJ 08543 USA

rcar@Princeton.EDU
InAs/GaAs SQUARE NANOMESAS: MULTIMILLION-ATOM

MOLECULAR DYNAMICS

SIMULATIONS ON PARALLEL COMPUTERS

Xiaotao Su1, R K Kalia1, A Nakano1, P Vashishta1, A Madhukar2

1

Concurrent Computing Laboratory for Materials Simulations,

Biological Computation and Visualization Center,

Department of Physics & Astronomy and Department of Computer Science,

Louisiana State University

 Baton Rouge, LA 70803 USA

2

Photonic Materials and Devices Laboratory, Departments of Materials

Science and Physics, University of Southern California

Los Angeles, CA 90089 USA

xsu@rouge.phys.lsu.edu

Surface energies of GaAs and InAs for the (100), (110), and (111) orientations have been

calculated. Both molecular dynamics (MD) method and conjugate gradient method are

used and the results are in excellent agreement. Surface reconstructions on GaAs(100)

and InAs(100) are studied via the conjugate gradient method. We have developed a new

model for GaAs(100) and InAs(100) surface atoms. Not only does this model reproduce

well surface energies for the (100) orientation, it also yields (12) dimer lengths in

accordance with ab initio calculations. We have performed large-scale molecular

dynamics simulations to investigate the mechanical stresses in InAs/GaAs nanomesas

with {101}-type sidewalls. The in-plane lattice constant of InAs layers parallel to the

InAs/GaAs(001) interface are found to exceed the InAs bulk value at the 12th monolayer

(ML) and the hydrostatic stresses in InAs layers become tensile above ~ 12 ML. Hence,

it is not energetically favorable to have InAs overlayers thicker than 12 ML. This may

explain the experimental findings of the growth of flat InAs overlayers with self-limiting

thickness of ~ 11 ML on GaAs nanomesas. We have also investigated the lateral size

effects on the stress distribution and morphology of InAs/GaAs square nanomesas using

MD simulations. Two nanomesas with the same vertical size but different lateral sizes

are simulated. For the smaller mesa, a single stress domain is observed in the InAs

overlayer, whereas two stress domains are found in the larger mesa. This indicates the

existence of a critical lateral size for stress domain formation in accordance with recent

experimental findings. It is found that the InAs overlayer in the larger mesa is laterally

constrained to the GaAs bulk lattice constant but vertically relaxed to the InAs bulk

lattice constant.
EXPLOITING NANOFILM COATINGS IN MICROFLUIDIC

DEVICES FOR BIOSENSING

Paul Cremer

Department of Chemistry

Texas A & M University

College Station TX 77843 USA

cremer@mail.chem.tamu.edu

This talk will explore new combinatorial methods inside microfluidic devices for

biosensor applications. Fluid heterogeneous coatings on the nanometer scale provide the

key to multivalent ligand receptor attachment a cell surface mimics. Several innovative

new architectures will be described.
TECHNIQUES FOR GUIDING THE ASSEMBLY OF FCC, BCC,

HCP, TETRAGONAL AND TRICLINIC PHOTONIC CRYSTALS

Preston Landon1, L Bourree2, R Glosser2

A Zakhidov1, R Baughman3

1

Nano Tech Institute and Department of Physics,

2

Department of Physics,

3

Nano Tech Institute and Department of Chemistry,

The University of Texas at Dallas

McKinney TX 75071 USA

plandon@utdallas.edu

This paper describes a technique to guide the assembly of colloidal spheres into

crystalline structures. We have several geometric molds to guide colloidal spheres into

face centered cubic (FCC), tetragonal, body centered cubic (BCC), hexagonal close

packed, and triclinic crystalline structures. Our work has focused on FCC, triclinic and

tetragonal crystals. Here we lay down the basic geometry to yield all of the above

structures and show how FCC, tetragonal and triclinic originate from a similar template.

We also introduce an inexpensive method that we have been developing over the last year

and a half for creating these crystalline structures up to 1 cm long with colloidal spheres

5um or larger. It has recently been demonstrated possible to form the FCC structure with

colloidal spheres smaller than 5um, however, our focus and the thrust of our research is

to develop an inexpensive technique to create these structures with 200nm or larger

spheres.
A MECHANISTIC EVALUATION OF MECHANISMS OF

“NEAR-NANOSCALE” HIGH-CYCLE FATIGUE FAILURES IN

POLYSILICON THIN FILMS FOR MEMS

C. L. Muhlstein1, E. A. Stach2, and Rob O. Ritchie1

1

Materials Sciences Division, Lawrence Berkeley National Laboratory

and Department of Materials Science and Engineering,

University of California, Berkeley, CA 94720 USA

2

National Center for Electron Microscopy

 Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA

roritchie@lbl.gov

The fracture and fatigue resistance of micron-scale silicon-based, structural films are

important mechanical properties for the design, reliability and long-term durability of

micromechanical devices, especially MEMS. Contrary to conventional wisdom on the

mechanisms of fatigue, recent work has established that such brittle thin films of singleand poly-crystalline silicon are susceptible to premature failure under cyclic loading

conditions, with failure occurring at long lives (>109 cycles) at approximately one half of

the single-cycle fracture strength. However, the mechanism(s) of such failures have

remained a mystery. In this presentation, a mechanism is presented for the fatigue of

thin-film LPCVD polysilicon based on extensive stress-life fatigue testing and highvoltage transmission electron microscopy. It is proposed that the fatigue process is

"surface dominated" and involves the mechanically-induced thickening of the native

oxide film, followed by environmentally-assisted subcritical cracking of the thickened

film. It is further shown that this mechanism is only specific to thin films and can not

cause failure in bulk silicon.
CACHE-CONSCIOUS ALGORITHM DESIGN

Viktor K. Prasanna

Department of EE-Systems

University of Southern California

3740 McClintock Ave, EEB 200C

Los Angeles, CA 90089-2562 USA

prasanna@usc.edu

The topic of cache performance has been well studied in recent years. It has been

clearly shown that the amount of processor-memory traffic is the bottleneck for

achieving high performance in many applications. While the topic of cache

performance has been well studied, much of the focus has been on dense linear

algebra problems. These problems possess very regular access patterns that are

known at compile time. In this paper, we take a unique approach to this topic by

focusing on other fundamental problems, which have poor cache utilization.

Optimizing cache performance to achieve better overall performance is a difficult

problem. Modern microprocessors are including deeper and deeper memory

hierarchies to hide the cost of cache misses. The performance of these deep memory

hierarchies has been shown to differ significantly from predictions based on a single

level of cache. Different miss penalties for each level of the memory hierarchy as

well as the TLB also play an important role in the effectiveness of cache-friendly

optimizations. These miss penalties vary from processor to processor and can cause

large variations in experimental results. In this work, we identify the key issues and

demonstrate algorithmic techniques by considering two key problem areas:

Effective utilization of cache memories is a key factor in achieving high

performance in computing signal transforms). Most optimization techniques for

computing the Discrete Fourier Transform (DFT) rely on either modifying the

computation and data access order or exploiting low level platform specific

details, while keeping the data layout in memory static. We propose a high level

optimization technique, dynamic data layout (DDL). In DDL, data reorganization

is performed between computations to effectively utilize the cache. This cacheconscious factorization of the DFT including the data reorganization steps is

automatically computed by using efficient techniques in our approach. An

analytical model of the cache miss pattern is utilized to predict the performance

and explore the search space of factorizations. Our technique results in up to a

factor of 4 improvement over standard FFT implementations and up to 33%

improvement over other optimization techniques such as copying on SUN

UltraSPARC-II, DEC Alpha and Intel Pentium III. Compared with the best

known FFT library (FFTW, MIT) our implementations run up to 2x faster on

DEC Alpha and up to 3x faster on UltraSPARC. For the Walsh Hadamard
Transform, compared with the state-of-the-art, our implementations achieve up to

4x performance improvement on DEC Alpha and UltraSPARC.

Graph problems are fundamental in a wide variety of fields, most notably

network routing, distributed computing, and computer aided circuit design.

Graph problems, as irregular problems, pose unique challenges to improving

cache performance, challenges that often cannot be handled using standard

cache-friendly optimizations. We develop the Unidirectional Space Time

Representation (USTR) and show that using this representation we can

develop cache-friendly implementations for a large class of algorithms. This

representation is very similar to the space-time representation used in systolic

array design, which also deals with partitioning the space as we do. However,

such systolic array designs do not have the added challenge of dealing with

cache conflicts and multiple levels of memory hierarchy. We also show how

this representation can be used to uniquely face the challenges posed by the

transitive closure problem. Using this representation we show up to a factor

of 2 improvement over a state-of-the-art cache-friendly optimization,

including those available in a research compiler. We use the Simplescalar

simulator to demonstrate improved cache performance. We also present a

number of optimizations to the Floyd-Warshall algorithm, Dijkstra’s

algorithm, and Prim’s algorithm. For the Floyd-Warshall algorithm we

present a recursive implementation that achieves a 6x improvement over the

baseline implementation. We also show that by tuning the base case for the

recursion, we can further improve performance by approximately 20%. We

also show a novel approach to tiling for the Floyd-Warshall algorithm that

achieves performance very close to that of the recursive implementation.

State-of-the-art research compilers cannot generate these implementations.

The work reported here summarizes ongoing efforts at USC. These efforts are developing

algorithmic techniques to improve the performance of signal processing algorithms

(Signal Processing algorithms Implementation Research for Adaptable Libraries

(SPIRAL) project, www.ece.cmu.edu/~spiral) and algorithmic techniques to improve the

performance of data intensive applications on advanced architectures (Algorithms for

Data Intensive Applications on Intelligent and Smart Memories, http://advisor.usc.edu).
SELF-CONSISTENT MODELING OF WEAKLY IONIZED

PLASMAS - CHALLENGES IN QUANTUM AND CLASSICAL

MECHANICS

Sadasivan Shankar1, B.V. McKoy2, L. Morgan3, C. Winstead2, B. Yu1

1

M.S. SC 12-205 Technology CAD

Intel Corp., 2200 Mission College Blvd.

Santa Clara, CA 95052 USA

2

California Institute of Technology

3

Kinema

sadasivan.shankar@intel.com

Weakly ionized plasmas are used in several critical steps in IC processing. They fall into

the regime of glow discharges (both normal and abnormal), which are characterized by

relatively lower pressures (< 1 Torr), large spatial gradients in electromagnetic fields, and

chemically active electronegative gases. These plasmas themselves are sustained by

electron induced ionization and chemistry at non-equilibrium conditions. For selfconsistent modeling of these plasmas in realistic processes, three components need to be

addressed - (1) Quantum mechanics-based calculations of electron impact probabilities,

(2) Self-consistent building of reaction data in gas phase and on surfaces, and (3) coupled

transport, reactions, and electromagnetics. There has been substantial progress in all the

three areas in the last two decades. The paper will examine the status and challenges in

each of the areas:- multi-length and time scales in weakly collisional plasmas,

difficulties in building a self-consistent chemical dataset for processing gases, the need

for efficient algorithms to exploit the recent availability of multi-processor systems, and

some application of these techniques to real systems. The intention is to show the

numerical and scientific challenges in combining the different techniques and data for

using plasma modeling as a predictive tool. The paper will span continuum mechanics,

kinetic theory, and quantum techniques and the numerical techniques used in each of the

areas.
COUPLED GROOVING AND MIGRATION OF INCLINED GRAIN

BOUNDARIES

Haris Wong

Department of Mechanical Engineering

Louisiana State University

Baton Rouge, LA 70803 USA

Hwong@ lsu.edu

Grain-boundary migration controls the growth and shrinkage of crystalline grains and is

important in materials synthesis and processing. A grain boundary ending at a free

surface forms a groove at the tip, which affects its migration. This coupled grooving and

migration is studied for a straight, inclined grain boundary intercepting a horizontal free

surface. Surface diffusion is taken to be the mass transport mechanism for grooving.

Previous work on a groove migrating at constant speed suggests that the grain boundary

is pinned if the inclination angle is small. We find that the grain boundary is never

pinned. The coupled motion can be separated into two time regimes. In Regime I, both

the grain-boundary and groove profiles grow with time following similarity laws. The

groove profile is symmetric about the groove root. The symmetry forces the grain

boundary to turn vertically at the tip, and this bending drives the migration. The selfsimilar profiles are shown to be linearly stable, and they grow continuously into Regime

II. In Regime II, the turning relaxes following two different paths depending on s/b,

where b is the initial inclination angle of the grain boundary and s is the supplementary

dihedral angle (p - s is the dihedral angle). For b > s/6, the groove root coordinates (x0,

y0) ~ (t1/2, t1/6) as time t -> ∞, whereas for b < s/6, (x0, y0) ~ (t1/4, t1/4) as t -> ∞.

These results come from asymptotic expansions and agree with a finite-difference

solution of the coupled equations. They show that the grain boundary is never pinned.

The asymptotic solutions also apply to the Sun-Bauer method of measuring grainboundary mobility, and predict grain-boundary profiles that agree better with

experiments.
NUMERICAL TECHNIQUES FOR TIME-DEPENDENT DENSITY

FUNCTIONAL THEORY

Yousef Saad

Depaertment of Computer Science & Engineering

University of Minnesota

200 Union St SE 4-192 EE/C Sci

Minneapolis, MN 55455 USA

saad@cs.umn.edu

Recently developed linear response methods based on time-dependent density

functional theory formalisms provide a new tool for calculating excited states

properties. These methods examine the response of a system when it undergoes a

certain initial periodic perturbation. Two distinct and broad methods are in use in

this context. In standard Time-Dependent LDA (TDLDA) (see, e.g., [1]) the Ordinary

Differential Equation (ODE) obtained from the time-dependent Kohn-Sham equation is

integrated over time. The major part of the cost associated with this technique comes

from the need to integrate over (relatively) large time intervals and the requirement to

integrate one ODE for each occupied state. A second approach developed in [1] works

in Fourier space. It builds a large coupling matrix K and computes its eigenvalues from

which transition energies can be obtained. The coupling matrix K is typically dense

and can be quite large. The biggest cost associated with this approach lies in the

computation of the matrix K which requires solving a Poisson equation for each matrix

entry.
FIRST PRINCIPLES STUDY OF ORGANOSULFUR MONOLAYERS

ON GOLD

Annabella Selloni

Department of Chemistry

122 Frick laboratory

Princeton University

Princeton, N.J. 08540 USA

aselloni@Princeton.EDU

Self-assembled monolayers (SAMs) of organosulfur molecules on gold and other metal

surfaces are intensely studied because of their many potential applications in various

areas of nanotechnology, including nanofabrication, chemical sensing, and molecular

electronics. In spite of their wide interest, the adsorption structure of most SAMs is not

well understood yet. Here I will discuss this issue on the basis of Density Functional slab

calculations for a few different organosulfur molecules on the Au(111) and Cu(111)

surfaces at various coverages. Results for methanethiol and dimethyl disulfide,

trifluoromethanethiol, benzenethiol, and L-cysteine will be presented. The question

whether these molecules adsorb as monomers (thiolates) or dimers (disulfides) will be

addressed.
PARALLELIZATION AND VISUALIZATION OF

COMPUTATIONAL NANOTECHNOLOGY LCAO METHOD

J C Franiatte, S G Satterfield, G Bryant, Judith E. Devaney

National Institute of Standards and Technology

George Mason University

Gaithersburg, MD 20899-8911 USA

judith.devaney@nist.gov

Accurate atomic-scale quantum theory of nanostructures and nanosystems fabricated

from nanostructures enables precision metrology of these nanosystems and provides the

predictive, precision modeling tools needed for engineering these systems for

applications including advanced semiconductor lasers and detectors, single photon

sources and detectors, biosensors, and nanoarchitectures for quantum coherent

technologies such as quantum computing. The tight-binding model based upon the Linear

Combination of Atomic Orbitals (LCAO) method provides an atomistic theory for

nanostructures which is accurate and easy to implement(1). The tight-binding method is

ideal for modeling small nanostructures. However, the method becomes impractical to

use on sequential computers, due to long run times, for modeling nanostructures with

more than 25,000 atoms. Dramatic improvements in run time can be achieved through

parallelization. We parallelize this method by dividing the structure into layers.

Communication is across layers. First we create the structure. Then we solve the

Hamiltonian equation for each atom considering only nearest neighbors using

PARPACK(2). This parallel implementation is nearly linear in time. The output of the

code is transferred to the NIST immersive environment where we study the structure

interactively. This provides us with a detailed inspection and visualization of the

structures and the atomic scale variation of calculated nanostructure properties that is not

possible with any static graphical representation. We save the interaction with the

structure in the immersive environment as a quicktime movie. The parallel

implementation can handle arbitrary nanostructure shapes through an input file

specification procedure. Structures of up to one million atoms are currently being studied.

[1] G. W. Bryant and W. Jaskolski, Physica E 11, 72 (2001).

[2] K. Maschhoff, D. Sorensen, "A portable implementation of ARPACK for distributed

memory parallel architectures", Preliminary proceedings, Copper Mountain Conference

on Iterative Methods, 1996.
NANOLOGIC: A LOGICAL BRIDGE TO NANOCOMPUTING

Robert W. Schmieder

Nanologic Inc.

4295 Walnut Blvd.

Walnut Creek, CA 94596 USA

schmieder@cordell.net

Almost all attempts to introduce nanoscale devices into electronic computers have

focused on making the devices operate as logical switches. As the fabrication dimensions

drop below 100 nm this is an increasingly difficult and ultimately impossible challenge.

We have taken a different approach. Instead of forcing the processor to conform to

defined data structures, we propose forcing the data to conform the defined processor

structures. The appropriate data structures are neither pure digital nor pure analog, but

intrinsically hybrid. By defining the data properly, we can exploit the extraordinarily rich

(and growing) inventory of nanoscale devices that have nonlinear, intrinsically hybrid,

transfer characteristics. Arrays of such hybrid devices, in which the output from one

device is used as the input to the next, will constitute a hybrid computer. Such computers

can be built in any applications- specific architecture to further exploit the hybridicity of

the data. Computers operating on this nanologic principle will have far greater density,

and therefore greater logic throughput than any pure analog or pure digital computer.

They will find best applications as simulators of physical systems. They could use direct

analog and digital I/O making the choice for sensor arrays. Conservative estimates

indicate a nanologic computer would have 2-4 orders of magnitude higher logic

throughput than the conventional computers. Applications include military (smart

weapons, nuclear design, burst decision-making, etc), industrial (weather prediction,

structural and fluid engineering, drug design, etc), commercial (implantable personal IT

aids, sensors for the disabled, smart robots, entertainment, artistic creation tools, etc.),

and scientific (molecular dynamics, social behavior, morphogenesis, chaotic systems,

etc.). We believe that hybrid logic computers, of the nature described here, are inevitable,

and that they will be widespread within ten years.

In this presentation, we will describe the technical basis of nanologic computing, current

technology for implementing it, the design process for nanologic circuits, and potential

applications of the technology.