[SY-E4] Symposium E-4

[SY-E4] High-performance first-principles calculation software development with applications to the zirconium

^○Haifeng Song^1,2, Xingyu Gao^1,2, Jun Fang^1,2, Yafan Zhao², Han Wang², Deye Lin² (1.Institute of Applied Physics and Computational Mathematics, China, 2.CAEP Software Center for High Performance Numerical Simulation, China)

With the development of high-performance computer, first-principles calculation becomes to be a feasible way in many nuclear material research fields. In this talk, we will give two examples to demonstrate it. Firstly, we develop two high-performance oriented methods for wave functions in solving the Kohn-Sham equations: a more parallel scalable FFT and optimal extrapolation order for the initial guess at next time step. Armed with adaptive time stepping, we estimate the threshold displacement energy of zirconium by large-scale first-principles calculations. We utilize CESSP to realize the calculations of about 100 tasks on the Tianhe-2 supercomputer in 3 months, where each task is the first-principles molecular dynamic simulation of 9600 valence electrons and 1 picosecond. Compared to classical molecular dynamic simulations, we arrive at the results closest to most recent experiment. Secondly, we have combined a novel crystal structure search method based on the basin hopping algorithm into our first-principles code. Several improvements were implemented, including a symmetry structure generation algorithm based on the crystal space groups, a structure adjustment method based on a virtual spring-force to adjust unreasonably structures. The method is also highly paralleled to make full use of the computing resources. We have applied the method into the structure searching of Zr hydrides (ZrHx, x= 0.5, 1.0, 1.5, 2.0). All experimentally observed Zr hydrides are reproduced, and several new structures were found. The dynamic and thermodynamic stability of these Zr hydrides will also be discussed.