Calculations of positron annihilation lifetime in solid based on finite difference and conjugate-gradient methods

Abstract

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 agreement with the available experimental data. Furthermore, all the results of our calculations demonstrate the accuracy and efficiency of the method from different aspects.