Langevin Thermostat for Rigid Body Dynamics

TL;DR

This paper introduces a novel Langevin thermostat method for rigid body simulations using quaternions, providing accurate NVT sampling and efficient integrators tested on water models.

Contribution

It develops a new quaternion-based Langevin thermostat with quasi-symplectic integrators for improved rigid body simulation accuracy.

Findings

Effective sampling of NVT distribution in rigid molecules

Performance validated on TIP4P water model

Guidelines for optimal thermostat parameter selection

Abstract

We present a new method for isothermal rigid body simulations using the quaternion representation and Langevin dynamics. It can be combined with the traditional Langevin or gradient (Brownian) dynamics for the translational degrees of freedom to correctly sample the NVT distribution in a simulation of rigid molecules. We propose simple, quasi-symplectic second-order numerical integrators and test their performance on the TIP4P model of water. We also investigate the optimal choice of thermostat parameters.