Basics and Limitations in Computational

Materials Design- What we should learn before

starting computer simulation -

January 21th (Tue.)16:00 − 17:30

Venue : Lecture room 102 in Material Educational Bldg. (B01)

Prof. KAWAZOEYoshiyuki

GP-MS Office(B04)E-mail: gpms-office@grp.tohoku.ac.jphttp://gp-ms.tohoku.ac.jp

Contact :

GP-MS Seminar on

Central hall(C01)

Materials Collaborative Research Bldg. (B04)

Basics and Limitations in Computational Materials Design

- What we should learn before starting computer simulation -

Yoshiyuki Kawazoe

There are two big user groups in supercomputer, i. e. FEM (Finite Element

Method) and DFT (Density Functional Theory) users. There is a clear difference in

these two methods; FEM has a history of 200 years and is well established, problems

remain there are mainly how to handle a large number of mesh points. Howerver, in

our field of DFT, which has a history of only a half century and the basic

formulation is still in a progessing phase. The main problems in DFT are (1) It is a

complete formulation for many electron system but only for the ground state, and (2)

Exc (exchange-correlation functional) is not known. Most of the recent works based

on DFT are simply phenomenogy and not possible to be catagolized as ab initio (or

first principles) calculations, since they use Exc as parameters to fit to experimental

observations. In the elementary particle physcs (I graduated), always theoretician

predicts something new and experimentalists follow this prediction. Theory first! In

our field of computational materials design, we fundamentally know everything; our

system is composed of nucleus and electrons, which all interact with Coulomb force

(1/r functional form comes from the 3D space property), and the governing equation

is quantum mechanical Shroedinger/Dirac equation. Therefore we can construct a

rule-based method to predict new materials, but the basic limitation comes from the

slow speed of the present supercomputer, and suitable approximations should be

introuced case by case.

Reference

“Computational Materials Science - From Ab Initio to Monte Carlo Methods -”, Springer

Series in Solid State Sciences, Vol. 129, (1999.4), K. Ohno, K. Esfarjani and Y. Kawazoe.