A unified thermostat scheme for efficient configurational sampling for classical/quantum canonical ensembles via molecular dynamics

TL;DR

This paper introduces a unified second-order scheme for thermostats in molecular dynamics, improving configurational sampling efficiency across classical and quantum ensembles, and demonstrating broad applicability and accuracy enhancements.

Contribution

A novel second-order scheme that unifies various thermostats, including Langevin, Andersen, and Nosé-Hoover, for improved configurational sampling in molecular dynamics.

Findings

The scheme enhances accuracy by an order of magnitude for coordinate-dependent properties.

It is effective across different thermostat types and molecular systems.

The method significantly improves efficiency in path integral molecular dynamics.

Abstract

We show a unified second-order scheme for constructing simple, robust and accurate algorithms for typical thermostats for configurational sampling for the canonical ensemble. When Langevin dynamics is used, the scheme leads to the BAOAB algorithm that has been recently investigated. We show that the scheme is also useful for other types of thermostat, such as the Andersen thermostat and Nos\'e-Hoover chain. Two 1-dimensional models and three typical realistic molecular systems that range from the gas phase, clusters, to the condensed phase are used in numerical examples for demonstration. Accuracy may be increased by an order of magnitude for estimating coordinate-dependent properties in molecular dynamics (when the same time interval is used), irrespective of which type of thermostat is applied. The scheme is especially useful for path integral molecular dynamics, because it consistently improves the efficiency for evaluating all thermodynamic properties for any type of thermostat.