Pressure control using stochastic cell rescaling

TL;DR

This paper introduces stochastic cell rescaling, a new first-order barostat for molecular dynamics that accurately reproduces volume fluctuations, improving upon traditional methods by combining efficiency with correct ensemble sampling.

Contribution

The paper presents stochastic cell rescaling, a novel barostat that correctly samples volume fluctuations and can be easily integrated into existing molecular dynamics codes.

Findings

Reports volume fluctuations compatible with the isobaric ensemble.

Effective in both equilibration and production phases.

Tested successfully on membrane simulations.

Abstract

Molecular dynamics simulations require barostats to be performed at constant pressure. The usual recipe is to employ the Berendsen barostat first, which displays a first-order volume relaxation efficient in equilibration but results in incorrect volume fluctuations, followed by a second order or Monte Carlo barostat for production runs. In this paper, we introduce stochastic cell rescaling, a first-order barostat that samples the correct volume fluctuations by including a suitable noise term. The algorithm is shown to report volume fluctuations compatible with the isobaric ensemble and its anisotropic variant is tested on a membrane simulation. Stochastic cell rescaling can be straightforwardly implemented in existing codes and can be used effectively both in equilibration and in production phases.