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Quantum diffusion in liquid para-hydrogen from ring-polymer molecular dynamics

Miller, Thomas F., III and Manolopolous, David E. (2005) Quantum diffusion in liquid para-hydrogen from ring-polymer molecular dynamics. Journal of Chemical Physics, 122 (18). Art. No. 184503. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:MILjcp05d

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Abstract

We have used the ring-polymer molecular dynamics method to calculate approximate Kubo-transformed velocity autocorrelation functions and self-diffusion coefficients for low-pressure liquid para-hydrogen at temperatures of 25 and 14 K. The resulting diffusion coefficients are shown to be consistent with experimental shear viscosities and the established finite-size relation D(L)~=D([infinity])–2.837kBT/6pietaL, where kB is the Boltzmann constant, T the absolute temperature, eta the shear viscosity, and L the length of the (cubic) simulation cell. The diffusion coefficients D(L) obtained in simulations with finite system sizes are therefore too small. However, the extrapolation to infinite system size corrects this deficiency and leads to excellent agreement with experimental results. This both demonstrates the influence of system-size effects on quantum mechanical diffusion coefficients and provides further evidence that ring-polymer molecular dynamics is an accurate as well as practical way of including quantum effects in condensed phase molecular dynamics.


Item Type:Article
Additional Information:©2005 American Institute of Physics. Received 13 December 2004; accepted 25 February 2005; published 6 May 2005. The authors would like to thank Paul Madden for stimulating discussions, David Chandler for helpful comments on an early draft of this manuscript, and Joel Bowman for providing them with computer time on a linux cluster for their largest (864 molecule) RPMD calculations.
Subject Keywords:molecular dynamics method, self-diffusion, liquid theory, hydrogen, viscosity
Record Number:CaltechAUTHORS:MILjcp05d
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MILjcp05d
Alternative URL:http://dx.doi.org/10.1063/1.1893956
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11063
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:25 Jun 2008
Last Modified:26 Dec 2012 10:08

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