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Computer simulation of the velocity autocorrelation function at low density
Author(s) -
Garland Gregory E.,
Dufty James W.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560220811
Subject(s) - autocorrelation , statistical physics , function (biology) , molecular dynamics , correlation function (quantum field theory) , lennard jones potential , radial distribution function , thermodynamics , physics , chemistry , computational chemistry , mathematics , quantum mechanics , statistics , biology , evolutionary biology , dielectric
Transport coefficients and other dynamic properties of fluids may be determined from appropriate time correlation functions, which in principle may be calculated by molecular dynamics computer simulation. At low densities the correlation functions do not decay to zero in a sufficiently short time to ignore systematic errors inherent in the simulation, unless a very large number of particles are used. Here we describe the results of a computer simulation of the velocity autocorrelation function at a reduced density of nσo 3 = 0.03 for a Lennard‐Jones gas at several temperatures. The associated memory function is found to have a small negative part at low temperatures, which is interpreted as being due to the attractive part of the potential. The results obtained for 108 particles are checked at a single temperature for a system of 2916 particles. Several models for the memory function, commonly used for liquid densities, are tested for the low‐density case considered here.