The influence of thermostats and manostats on reverse nonequilibrium molecular dynamics calculations of fluid viscosities

Reverse nonequilibrium molecular dynamics to calculate the shear viscosity of Lennard-Jones liquids was extended to simulations at constant number of particles, constant volume, and constant pressure using a Berendsen thermostat and a Berendsen manostat. Using additional systems such as water and hexane, we also report on the performance of shear viscosity calculations of systems with electrostatic and nontrivial intramolecular interactions when a manostat is applied. We compare the shear viscosities of simulations using no coupling, only temperature coupling, and temperature and pressure coupling and characterize discrepancies, where observed. From this, we deduce guidelines for when and how manostats can be usefully applied in reverse nonequilibrium simulations.