%0 Journal Article
%@ 1362-3028
%A Stinson, JL
%A Kathmann, SM
%A Ford, IJ
%D 2014
%F discovery:1458328
%J Molecular Physics
%K Langevin thermostat, small system, constraints
%N 22
%P 2920-2923
%T Dynamical consequences of a constraint on the Langevin thermostat in molecular cluster simulation
%U https://discovery.ucl.ac.uk/id/eprint/1458328/
%V 112
%X © 2014 Taylor and Francis. We investigate some unusual behaviour observed while performing molecular dynamics simulations of small molecular clusters using a constrained Langevin thermostat. Atoms appear to be thermalised to different temperatures that depend on their mass and on the total number of particles in the system. The deviation from the zeroth law of thermodynamics can be considerable for small systems of heavy and light particles. We trace this behaviour to the absence of thermal noise acting on the centre of mass of the system. This is demonstrated by solving the stochastic dynamics for the constrained thermostat and comparing the results with simulation data. By removing the constraint, the Langevin thermostat may be restored to its intended behaviour. We also investigate a Langevin thermostat constrained to have zero total force acting on its centre of mass, and find similar deficiencies.
%Z This is an Accepted Manuscript of an article published by Taylor & Francis in Molecular Physics on 19/05/14, available online: http://www.tandfonline.com/10.1080/00268976.2014.917732.