Ab initio molecular dynamics via density based energy functionals

TL;DR

This paper proposes a density-based energy functional approach for ab initio molecular dynamics, incorporating positivity constraints and nonlocal pseudopotentials, with applications to small metal clusters.

Contribution

It introduces a novel density functional method with positivity constraints and a new pseudopotential inclusion technique for improved ab initio molecular dynamics.

Findings

Accurate equilibrium geometries for Na and Mg clusters

Enhanced results with the new pseudopotential approach

Demonstration of the method's effectiveness on small metal systems

Abstract

The use of energy functionals based on density as the basic variable is advocated for ab initio molecular dynamics. It is demonstrated that the constraint of positivity of density can be incorporated easily by using square root density for minimization of the energy functional. An ad hoc prescription for including nonlocal pseudopotentials for plane wave based calculations is proposed and is shown to yield improved results. Applications are reported for equilibrium geometries of small finite systems, viz. dimers and trimers of simple metal atoms like Na and Mg, which represent a rather stringent test for approximate kinetic energy functionals involved in such calculations.