期刊论文

Cheng, G

英文

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

0168-583X

2023

537

71-76

10.1016/j.nimb.2023.01.011

In summary, we have implemented the combination of finite difference method and conjugate gradient method in the positron annihilation lifetime calculations. From the perfect and defect calculations, the analysis shows that the positron wave functions could be optimized by conjugate gradient method efficiently without loss of accuracy. From the tests on mesh points and supercell sizes, the numerical results show that our calculations are extremely stable for different mesh points and supercells.

本校为第一且通讯机构

We employ a real-space grids technique to calculate positron annihilation lifetimes with pseudopotentials. This method is based on the two-component of density functional theory (TCDFT), the Hamiltonian operator of the Kohn-Sham equation is discretized on a point grid by the finite difference method (FDM), the positron eigenstates are searched by the conjugate-gradient method (CG) and the positron Kohn-Sham equation is solved by a self-consistent iteration method. We show that the numerical results under this scheme for bulk and monovacancy of positron annihilation lifetimes are in reasonable ...