gp-ms seminar on basics and limitations in …gp-ms.tohoku.ac.jp/data/20200107.pdfintrouced case by...
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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: [email protected]://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.