# Presentation: 293986

## Division of Materials Sciences and Engineering 

**Basic Energy Sciences **
**Advisory Committee Meeting**
**Omni Shoreham Hotel **
**Washington, DC**
**June 6, 2005**
**Harriet Kung **
**Division of Materials Sciences and Engineering**
**Office of Basic Energy Sciences, Office of Science**
**U.S. Department of Energy**

***Division of Materials Sciences and Engineering****** ***
***Reflection on BESAC Report on Theory and Computation***

***Basic Energy Sciences***
***Serving the Present, Shaping the Future***

## Theory and Computation A Confluence of Opportunities in Materials Sciences and Engineering 

_**Dramatic Progress in Theory and Modeling**_
**	****DFT, ab initio MD, Quantum MC, DMFT, etc****.**

_**New Computational Capabilities**_
**	****Workstation and Cluster- Universities and Labs Massively Parallel Computers- LBNL/NERSC, PNNL/EMSL, ANL, ORNL**

***Theory and Computation ******A Confluence of Opportunities in Materials Sciences and Engineering ***

**Direct image of a silicon crystal showing atom columns in pairs only 0.78 Angstroms apart**

**A first-principles method describing the dynamics of magnetic moments in materials**

**Charge Transport in Carbon Nanotubes**

**Source: A.P. Alivisatos**

_**New Scientific Frontiers**_
**	****Ultrasmall and Ultrafast Sciences, Quantum-Level Control of Matter and Information, Infusion of Bio Approaches and Techniques**

**Source: A.P. Alivisatos**

_**New Experimental Capabilities**_
**	****Tabletop Tools:  STM, NMR, STEM, fs-Laser**
**	****Large Facilities: SNS, NSRCs, LCLS **

**Source: G.M. Stocks et al.**** **

**Source: S. Pennycook et al.**

## Theory and Computation in Materials Sciences and Engineering

**Electronic Structure**
- 		Band structure, simulations, model development, many body theory, spin dynamics
- 	 	Correlation of electronic structure with materials properties; self-organized electronic structure 	(FQHE, stripes); superconductivity, magnetism, chemical reactivity, hardness, toughness
- 	 	Dynamics & fluctuations
**New Materials**** **
- 	 	New combinations of atoms and new degrees of complexity, e.g., competing interactions among 	spin, charge, lattice, Vortex matter, Photonic Band Gap Materials, Granular Materials
- 	 	Nano and other low-dimensional structures
- 	 	Materials created by energetic processes
- 	 	Self assembly, pattern formation
- 	 	Modeling complex fluids, colloids, polymers, and biomolecular materials
**Surfaces and Interfaces**
- 	 	Electronic surface structure, surface reconstruction
- 	 	Patterns of crystal growth
- 	 	Solid – liquid interfaces, corrosive, adhesive, and electrochemical properties
- 	 	Defects in solids
**Development of Computational Techniques**
- 	 	Spin Dynamics, Inverse Band Structure, Linear Expansion in Geometric Objects, Algorithm 	Development, Hyperdynamics

## Nanoscale Science
Biomimetic Materials and Energy Processes 
Correlated Electrons in Solids 
Excited Electronic States
Magnetic Spin Systems & Single Electron Devices
Defects in Solids 
Control of Energy, Matter &  Information at the Quantum Level
Ultrafast Physics and Chemistry
Control of Chemical Transformations

***Nanoscale Science***
***Biomimetic Materials and Energy Processes ***
***Correlated Electrons in Solids ***
***Excited Electronic States***
***Magnetic Spin Systems & Single Electron Devices***
***Defects in Solids ***
***Control of Energy, Matter &  Information at the Quantum Level***
***Ultrafast Physics and Chemistry***
***Control of Chemical Transformations***

***New Opportunities Identified by the Report Match DMS&E Priorities***

## Simulations of Self Assembly of Gold Nanoparticles

**►****	****Simulations have explored formation of nanocrystals composed of passivated gold clusters.  **
**►****	****Assembly begins by formation of chain structures.  The length of the chains formed as well as the nanoparticle size and temperature all affect the resulting properties  such as tetragonality, elastic properties of the lattice.**
**►****	****Another related project has been examining how  nanoparticles can be tailored to encourage chosen structures.  (i.e., polymer tethers, reactive regions, etc.)**

**New insights on self assembly of nanoparticles were provided by atomistic simulations.**
**DMS&E Theoretical Condensed Matter Physics CRA**

**Notes:**
To retain or amplify on their nano properties, nanoparticles must be assembled without consolidating.  The Landman group has done simulations exploring how Au clusters form, how they are passivated, and how they assemble.  (Also looked at Au wires.)  While no longer unique, they were a leader, have been very thorough, and present the results well.  The Glotzer group at U. Mich. has explored how to create nanoparticles which will self assemble in specified ways.  (They have appeared in Nature.)  Torquato (in Engg Phys.) has worked on the same types of problems.
__________________________________________________________________________________________________________________________________________________

Self-assembly of passivated-nanocrystalline superlattices.  Multiple levels of self-assembly:  Au atoms into low-energy-faceted nanocrystals, alkylthio molecules into densely packed ligands, passivated nanocrystals into temperature dependent superlattice structures.  At 100K, the free clusters exhibit bimodal chain ordering.  These self assemble into an Orhom structure (with the axis normal to the displayed plane much shorter than the other two.)  with a different chain ordering consistent with a low energy stable lattice.  

## Theoretical Strength - Deformation in Nanostructured Metals

** **

***Theoretical Strength - Deformation in Nanostructured Metals***

**As-deposited****	****	****  Under applied strain****	****3-D view of the interface structure**

**Computation studies shed light on the role of defects in controlling ultimate strength in solids.****	****	****	****DMS&E Mechanical Behavior CRA**

## New Ideas Underlie Experimental Interpretations

***k*****||****-resolved contributions from Fe(001) minority states to the STM current (n****1****) and corrugation (n****2****) for different applied fields. Yellow (red) denotes positive (negative) values.**

**Charge density above the Fe(001) surface showing the anticorrugation for an applied electric field.**

**Scanning Tunneling Microscope data are normally interpreted as directly giving the positions of the atoms on a surface. Calculations of the effect indicate situations where the electric field induced by the tip modify the electronic densities and give false indications for the atomic positions.**

***New Ideas Underlie Experimental Interpretations***

**Angular Resolved Photoemission experiments reveal the breakup of the Fermi surface in high Tc cuprate superconductor by forming pseudogap, starting at about 180K and reaching the isolated points for the superconducting state at 85K.  That these points exist is strong evidence for the d-wave character of the superconductivity.  The ability to see this detail was enabled by the theorist’s realization that one could characterize the energy dependence of the experimental data that made it possible to extract the information.**

**Theoretical efforts allow interpretations of photoemission to reveal pseudogap in superconducting cuprate and account for tip effect in STM observations.**
**DMS&E Theoretical Condensed Matter Physics CRA**

## Theory of Experiments

**To advance frontiers in computational materials science through strong coupling with table-top experimental efforts as well as at BES user facilities to benchmark theoretical models and to guide experimental designs.**

- Theory vs. Experiment:
- silicon nanoclusters

_**Excited State Electronic Structure**_

**Large Facilities Science ****	****Table-top Science**

**Theory and Computation**

## CMSN Cooperative Research Teams

| Current Teams
Under
DMS&E 
Support | Excited State Electronic Structure and Response Functions: Louis, Rehr
Magnetic Materials Bridging Basic and Applied Science: Stocks, Harmon
Microstructural Effects on the Mechanics of Materials: Wolf, LeSar
Fundamentals of Dirty Interfaces: From Atoms to Alloy Microstructures: Rollett, Karma
Predictive Capability for Strongly Correlated Electron Materials: Scalettar, Pickett |
| --- | --- |
| Potential Additions | Multiscale Studies of Formation and Stability of Surface-based Nanostructures |

**The mission of the **_**C**_**omputational **_**M**_**aterials **_**S**_**cience **_**N**_**etwork is to advance frontiers in computational materials science by assembling diverse sets of researchers committed to working together to solve relevant materials problems that require cooperation across organizational and disciplinary boundaries. **

***Collaborative Programs to Tackle Complex Grand Challenges***

**For more information on CMSN: **
**http://www.phys.washington.edu/users/cmsn/**

## Materials Theory Institute (MTI)

**A visitors program designed to attract leading scientists with expertise complementary to that available at the host institutions **
**Foster growth and expansion of theoretical science by catalyzing interdisciplinary interactions and collaborations**
**Format enables mobile, well focused, and highly interactive character research**
**Tackle a rich variety of the compelling and topical scientific problems that strengthen and expand the capabilities of the home institution**
**Regular workshops focused on the most urgent emerging topics to attract leading world scientists to advance the field and contribute to the creative and stimulating atmosphere of the Institute**

***Collaborative Programs to Tackle Complex Grand Challenges***

**DMS&E currently supports MTI projects at ANL and BNL**

**Notes:**
Although they sometimes collaborate, the ANL and BNL MTI’s are separate entities and operate somewhat differently.  

The MTI’s are not at all focused on computing.

## DMS&E recognizes many outstanding materials sciences issues could benefit considerably from high-end computing. 

Access to high-end computer resources is a limiting factor for DMS&E researchers.
Reliability of time allocation over a period of several years is critical for optimum design of computation strategies.

**Access to high-end computer resources is a limiting factor for DMS&E researchers.**
**Reliability of time allocation over a period of several years is critical for optimum design of computation strategies.**

***Availability and Access to DMS&E Computational Resources***

**DMS&E is pursuing options to**
**Seek further resource allocations within Office of Science/ASCR**
**Leverage resources at other computer centers (e.g., NSF Centers)**
**Expand DOE Centers**
**Provide additional clusters**

## Software as Shared Research Infrastructure

**Hyperdynamics and other multiple time scale techniques **
**Geometric Cluster Algorithm (GCA) for complex fluids simulation **
**Linear Expansion of Geometric Objects (LEGO)**
**Inverse band structure methods**
**Solving for many electron wave functions**
**Shared software and codes in CMSN Collaborative Research Teams **

**Current efforts in algorithm and technique development:**

**Compelling future needs to develop new algorithms and codes for general use at DOE’s leadership-class computing facilities**

**GCA yields several orders of magnitude efficiency improvement of complex fluids simulations**

**Bridging intermediate steps to incorporate the effects of rare but critical events into dynamic simulations**

**Expansion of Complex Solids enables wide search for lowest energy structures using search algorithms**

## New Avenues to Computation

**Spintronics – dissipationless spin currents**
**Quantum Computing – magnetic molecules & entangled states**

**An equivalent to an “Ohm’s law” was discovered for quantum spintronics-  Spin current can be induced by the electric field thru the spin-orbit coupling, and it can flow without dissipation! **

**Science 301, 1348 (2003)**

**►****Theoretical effort expanding on using spin as the mechanism of quantum computing and showing the spin-orbit coupling can help rather than being only a loss mechanism.**
**►****Starting a project based on using the spin resonance of N isolated and positioned by an enclosing C****60**** molecule.**

## Increase support for investigators at universities and labs – particularly in nanoscience, correlated electrons systems, defects in solids, electronically excited states 
Provide additional computer clusters 
Encourage theorists and computer scientists to work with facility users and other experimental efforts
Expand collaborative efforts
Enhance usage of high-end computers 
Support develop new algorithms and codes for general use
Support research in new forms of computing (spintronics, quantum computing)

**Increase support for investigators at universities and labs – particularly in nanoscience, correlated electrons systems, defects in solids, electronically excited states **
**Provide additional computer clusters **
**Encourage theorists and computer scientists to work with facility users and other experimental efforts**
**Expand collaborative efforts**
**Enhance usage of high-end computers **
**Support develop new algorithms and codes for general use**
**Support research in new forms of computing (spintronics, quantum computing)**

***Outlooks for Theory and Computation in DMS&E***

**The DMS&E FY2006 Budget includes an increase of $3M for theory and computation in nanoscience.**

## DMS&E Challenges and Strategies in Theory and Computation

***DMS&E Challenges and Strategies in Theory and Computation***

***Challenges: ***
**Build a “properly balanced” program under resource constraints**
**Maintain a coherent basic unity of theory, computation and experimental activities**
***Investment Strategies***
**Seek close coupling with nanoscience**
**Influence BES User Facilities to enhance support for theory and computation **
**Expand efforts through new funding opportunities (e.g., Hydrogen Fuel Initiative) **
**Contribute to and take advantage of BES strategic growth areas (i.e., ultrafast science, energy security research)**

***Thank You!******The report reinforces DMS&E investment strategies and will guide our future theory and computation activities.***