Fast quasi-centroid molecular dynamics

TL;DR

This paper introduces a rapid implementation of quasi-centroid molecular dynamics that approximates the potential of mean force as a separable correction, enabling efficient vibrational spectra calculations with high accuracy.

Contribution

It presents a novel, computationally efficient method for approximating the quasi-centroid potential, improving vibrational spectra predictions in molecular dynamics.

Findings

Excellent agreement with QCMD for water and ammonia spectra

Good agreement with quantum mechanical spectra of methane

Efficient computation of vibrational spectra using the new method

Abstract

We describe a fast implementation of the quasi-centroid molecular dynamics (QCMD) method in which the quasi-centroid potential of mean force is approximated as a separable correction to the classical interaction potential. This correction is obtained by first calculating quasi-centroid radial and angular distribution functions in a short path integral molecular dynamics simulation, and then using iterative Boltzmann inversion to obtain an effective classical potential that reproduces these distribution functions in a classical NVT simulation. We illustrate this approach with example applications to the vibrational spectra of gas phase molecules, obtaining excellent agreement with QCMD reference calculations for water and ammonia and good agreement with the quantum mechanical vibrational spectrum of methane.