New observations regarding deterministic, time-reversible thermostats and Gausss principle of least constraint

Date

2005

Authors

Bright, Joanne Nicole
Evans, Denis
Searles, Debra

Journal Title

Journal ISSN

Volume Title

Publisher

American Institute of Physics (AIP)

Abstract

Deterministic thermostats are frequently employed in nonequilibrium molecular dynamics simulations in order to remove the heat produced irreversibly over the course of such simulations. The simplest thermostat is the Gaussian thermostat, which satisfies Gauss's principle of least constraint and fixes the peculiar kinetic energy. There are of course infinitely many ways to thermostat systems, e.g., by fixing ∑i ∫ pi ∫μ+1. In the present paper we provide, for the first time, convincing arguments as to why the conventional Gaussian isokinetic thermostat (μ=1) is unique in this class. We show that this thermostat minimizes the phase space compression and is the only thermostat for which the conjugate pairing rule holds. Moreover, it is shown that for finite sized systems in the absence of an applied dissipative field, all other thermostats (μ≠1) perform work on the system in the same manner as a dissipative field while simultaneously removing the dissipative heat so generated. All other thermostats (μ≠1) are thus autodissipative. Among all μ thermostats, only the μ=1 Gaussian thermostat permits an equilibrium state.

Description

Keywords

Keywords: Autodissipation; Gauss's principle; Gaussian thermostats; Least constraint; Boundary conditions; Constraint theory; Deformation; Differentiation (calculus); Electric field effects; Energy dissipation; Mathematical models; Thermostats

Citation

Source

Journal of Chemical Physics

Type

Journal article

Book Title

Entity type

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DOI

10.1063/1.1900724

Restricted until

2037-12-31