First-principles Cluster Variation, Path Probability and Phase Field calculations to investigate microstructure formation under SIP project

Tetsuo Mohri (Tohoku University, Sendai, Japan)

Pavilón QUTE, Auditórium – 2. poschodie, FÚ SAV

Among computational materials science projects in Japan, the author has been involved in JST-SIP and K-/Post-K super computer projects. One of the aims in SIP project is to formulate coarse graining procedure which is inevi- table for the multiscale calculations. By taking Fe-based alloys as an example, one scheme of achieving first-principles microstructure evolution calculations is introduced. In this calculation, we attempted coarse graining on space and we were able to assign length scale uniquely. The author will introduce how the DFT calculations, Cluster Expansion Method (CEM), Cluster Variation Method (CVM) of statistical mechanics and Phase Field Method (PFM) are combined to perform first-principles multiscale calculations. Path Probability Method (PPM) is regarded as a natural extension of the CVM to time domain and one can deal with atomistic kinetics associated with, for instance, an order-disorder transition. Some of the recent progress in PPM calculations for vacancy mediated diffusion process is also discussed. For achieving higher precision, the introduction of local lattice relaxation into free energy is important. Our recent attempt of Continuous Displacement Cluster Variation Method is introduced.

In addition to these particular subjects of multiscale phase field calculations, the author will introduce recent status of computational materials science pro- jects in Japan, including SIP project and K- and post-K supercomputer projects.