Nuclear Quantum Effects in Liquid Water at Near Classical Computational Cost Using the Adaptive Quantum Thermal Bath

We demonstrate the accuracy and efficiency of a recently introduced approach to account for nuclear quantum effects (NQEs) 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 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 that of classical molecular dynamics, enabling simulations of up to millions of degrees of freedom.

Automated summary

The study demonstrates the accuracy and efficiency of a method called adQTB for accounting for nuclear quantum effects in molecular simulations. A refined algorithm is proposed with improved accuracy, and simulations of liquid water using adQTB are reported. Comparisons with reference calculations show excellent accuracy in a wide range of structural and thermodynamic observables, as well as infrared vibrational spectra.