University	  of	  Tsukuba	  	  | Center	  for	  Computational	  SciencesQuantum	  Condensed	  Matter	  Physics
SALMON:	  Scalable	  Ab-­‐initio	  Light-­‐Matter	  simulator	  for	  Optics	  and	  Nanoscience
Interactions between light and matter are the basis of a wide range of technologies. To gain a basic
understanding of the interaction, it is essential to realize electron dynamics in matter induced by thelight electromagnetic fields in a microscopic scale, 10-­‐9 (nano-­‐)meter in space and 10-­‐15 (femto-­‐)second in time. We have been developing a computer code SALMON, Scalable Ab-­‐initio Light-­‐Mattersimulator for Optics and Nanoscience, under a collaboration with researchers in Institute for
Molecular Science. It is based on time-­‐dependent density functional theory in microscopic scale.
SALMON is available at http://salmon-­‐tddft.jp.

rc

2 2@t

A=During	  laser	  irradiation

SALMON may describe coupled dynamics ofelectrons and electromagnetic fields in a multiscalemodeling. In microscopic scale, time-­‐dependent
Kohn-­‐Sham equation is solved in real space grid
representation. Maxwell equations for the lightelectromagnetic fields are solved employing finite-­‐Microscopic systemdifferencetime-­‐domain
method.
(Quantum mechanics)

Macroscopic system(Electromagnetics)
2Ground	  statei~@t4⇡J/c

After	  laser	  irradiation=ĤSALMON is optimized for latest processors ofdifferent architectures. Performances of
SALMON (Hamiltonian and stencil operations)are compared.

Electron motion in crystalline
silicon induced by intense andultrashort laser pulse.

Computational	  Design	  of	  Future	  Electronics	  Devices	  using	  First-­‐Principles	  Calculations
With cutting-­‐edge materials and minute electronic devices being produced by the latest nanoscale fabrication technology, it is essential forscientists and engineers to rely on first-­‐principles calculations to fully understand phenomena from the behavior of electrons. We develop
first-­‐principles calculation code “.”uses real-­‐space finite-­‐difference method for first-­‐principles calculation. The advantages of, which are superior toconventional plane wave methods, are2.	  Applicable	  to	  transport	  calculations.

1.Suitable	  for	  massively	  parallel	  computing.
1000

incident

x100

reflection

1010100
1000
Number  of  CPUs

transmission

nanostructure

electrodeyWhole	  System

Si bulk (1000 atoms)  Si  bulk  (1000  atoms)

electrodez

Computation  time  (sec)

H22O
Cluster (96 stoms)  H
O  Cluster  (96  atoms)

10000

As applications using, interface atomic structures are examined and fabrication procedures are developed to realize high-­‐performance and low-­‐energy-­‐loss electronic devices, e,g., SiC power devices. By investigating the origin of leakage current and carrier
scattering at interfaces, we propose prescriptions to improve device performance and demonstrate the applicability of the interface
structures.
Resistance	  increases	  by	  oxidation
300GateDrainCurrent	  (µA)

Source200
10000.0

SiC device

Scattering	  of	  carrier	  due	  to	  interface	  defects

Initial	  interface
Oxidation1
Oxidation2
Oxidation3

0.5
Bias	  (V)

Carrier	  scattering	  property	  obtained	  by	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  .

1.0Computational	  design	  of	  interface	  structure

Furthermore, we establish a basic technology of computational science to design interface structures and fabrication procedures of future
electronic devices.

contact	  address:	  pr@ccs.tsukuba.ac.jp

http://www.ccs.tsukuba.ac.jp/