Efficient mixed-force first-principles molecular dynamics

TL;DR

This paper introduces an efficient mixed-force approach for first-principles molecular dynamics that combines fast, approximate forces with accurate, converged forces to significantly reduce computational cost while maintaining accuracy.

Contribution

The method allows mixing of converged and approximate forces evaluated at different intervals, greatly enhancing efficiency in ab initio molecular dynamics simulations.

Findings

Efficiency increased by a factor of n, up to 10, without significant loss of accuracy.

Approximate forces evaluated with minimal basis set and Harris functional are sufficiently accurate.

Structural and dynamical properties remain reliable with the mixed-force approach.

Abstract

We present an efficient method to mix well converged ab initio forces with simpler and faster ones in molecular dynamics. While the cheap forces are evaluated every time step, the converged ones correct the trajectory only every n time steps. For convenience, both types of forces are calculated with the same basic scheme, using density functional theory, norm conserving pseudopotentials, and a basis set of numerical atomic orbitals. The cheap forces are evaluated with a short-range minimal basis set and the non-selfconsistent Harris functional. Since these evaluations are hundreds of times faster than those of the converged forces, they add a neglegible cost, and the boost in computational efficiency is approximately a factor n. Our results indicate that one can use values of n of up to 10, without affecting significantly the calculated structural and dynamical magnitudes.