Time-reversible Born-Oppenheimer molecular dynamics

TL;DR

This paper introduces a time-reversible Born-Oppenheimer molecular dynamics method that maintains energy conservation and detailed balance, enabling efficient and physically accurate simulations of nuclear and electronic motion.

Contribution

It develops a novel time-reversible scheme for Born-Oppenheimer molecular dynamics using self-consistent field methods, reducing computational cost while preserving physical accuracy.

Findings

Excludes long-term energy drift in simulations.

Requires only 2-4 self-consistency cycles per step.

Maintains detailed balance and time-reversal symmetry.

Abstract

We present a time-reversible Born-Oppenheimer molecular dynamics scheme, based on self-consistent Hartree-Fock or density functional theory, where both the nuclear and the electronic degrees of freedom are propagated in time. We show how a time-reversible adiabatic propagation of the electronic degrees of freedom is possible despite the non-linearity and incompleteness of the self-consistent field procedure. Time-reversal symmetry excludes a systematic long-term energy drift for a microcanonical ensemble and the number of self-consistency cycles can be kept low (often only 2-4 cycles per nuclear time step) thanks to a good initial guess given by the adiabatic propagation of the electronic degrees of freedom. The time-reversible Born-Oppenheimer molecular dynamics scheme therefore combines a low computational cost with a physically correct time-reversible representation of the dynamics, which preserves a detailed balance between propagation forwards and backwards in time.