Extended Lagrangian Born-Oppenheimer Molecular Dynamics with DFT+U

TL;DR

This paper introduces an efficient molecular dynamics method combining extended Lagrangian Born-Oppenheimer dynamics with DFT+U, enabling stable simulations with reduced computational cost for systems requiring orbital-dependent corrections.

Contribution

It develops a novel approach integrating XL-BOMD with DFT+U, eliminating iterative ground state optimization and improving simulation efficiency for complex materials.

Findings

Accurate and stable molecular trajectories achieved.

Reduced computational cost per time step.

Demonstrated on nitromethane liquid and UO₂ solid systems.

Abstract

Extended Lagrangian Born-Oppenheimer molecular dynamics (XL-BOMD) [Phys. Rev. Lett. vol. 100, 123004 (2008)] is combined with Kohn-Sham density functional theory (DFT) using a DFT+U correction based on the Hubbard model. This combined XL-BOMD and DFT+U approach allows efficient Born-Oppenheimer molecular dynamics simulations with orbital-dependent corrections beyond regular Kohn-Sham density functional theory. The extended Lagrangian formulation eliminates the need for the iterative self-consistent-field optimization of the electronic ground state prior to the force evaluations, which is required in regular direct Born-Oppenheimer molecular dynamics simulations. This method provides accurate and stable molecular trajectories, while reducing the computational cost per time step. The combined XL-BOMD and DFT+U approach is demonstrated with molecular dynamics simulations of a nitromethane molecular liquid and a system of solid nuclear fuel, UO$_2$, using self-consistent-charge density functional based tight-binding theory.