OBTAINING IONIC FORCES BY THE TOTAL-ENERGY TIGHT-BINDING METHOD

Abstract

Applying a non-orthogonal tight-binding method to calculate ionic forces in a moleculardynamics simulation vastly improves the transferability the model’s transferability to different environments, compared with the traditional empirical potential-driven molecular-dynamics. In this paper we present the details of computing derivatives of Hamiltonian and overlap matrix elements appearing in the Hellmann-Feynman expression for ionic forces in the NRL-TB model of tightbinding. The presented expressions are validated with the results obtained using a tight-bindingdriven molecular-dynamics program.