Effect of the Berendsen thermostat on dynamical properties of water

TL;DR

This study investigates how the Berendsen thermostat influences the dynamical properties of bulk water in molecular simulations, showing it preserves many fluctuation correlations but can introduce deviations at certain time scales.

Contribution

It provides a detailed analysis of the impact of the Berendsen thermostat on water dynamics, highlighting conditions where it accurately reproduces microcanonical behavior.

Findings

Preserves temporal correlations over wide frequency ranges.

Maintains global property fluctuations for short times.

Deviations occur at intermediate thermostat time constants, especially in supercooled water.

Abstract

The effect of the Berendsen thermostat on the dynamical properties of bulk SPC/E water is tested by generating power spectra associated with fluctuations in various observables. The Berendsen thermostat is found to be very effective in preserving temporal correlations in fluctuations of tagged particle quantities over a very wide range of frequencies. Even correlations in fluctuations of global properties, such as the total potential energy, are well-preserved for time periods shorter than the thermostat time constant. Deviations in dynamical behaviour from the microcanonical limit do not, however, always decrease smoothly with increasing values of the thermostat time constant but may be somewhat larger for some intermediate values of $\tau_B$, specially in the supercooled regime, which are similar to time scales for slow relaxation processes in bulk water.