Nuclear Quantum Effects in liquid water at near classical computational cost using the adaptive Quantum Thermal Bath

TL;DR

The paper presents an improved adaptive Quantum Thermal Bath method that accurately incorporates nuclear quantum effects in molecular simulations of liquid water at a computational cost similar to classical methods.

Contribution

An enhanced adQTB algorithm that accurately models nuclear quantum effects with reduced computational cost, validated against path integral calculations.

Findings

adQTB provides excellent accuracy for structural and thermodynamic properties

adQTB accurately reproduces infrared vibrational spectra

The method enables large-scale simulations with millions of degrees of freedom

Abstract

We demonstrate the accuracy and efficiency of a recently introduced approach to account for nuclear quantum effects (NQE) in molecular simulations: the adaptive Quantum Thermal Bath (adQTB). In this method, zero point energy is introduced through a generalized Langevin thermostat designed to precisely enforce the quantum fluctuation-dissipation theorem. We propose a refined adQTB algorithm with improved accuracy and we report adQTB simulations of liquid water. Through extensive comparison with reference path integral calculations, we demonstrate that it provides excellent accuracy for a broad range of structural and thermodynamic observables as well as infrared vibrational spectra. The adQTB has a computational cost comparable to classical molecular dynamics, enabling simulations of up to millions of degrees of freedom.