Correlations in the Motion of Atoms in Liquid Argon
Abstract
A system of 864 particles interacting with a LennardJones potential and obeying classical equations of motion has been studied on a digital computer (CDC 3600) to simulate molecular dynamics in liquid argon at 94.4°K and a density of 1.374 g cm^{3}. The paircorrelation function and the constant of selfdiffusion are found to agree well with experiment; the latter is 15% lower than the experimental value. The spectrum of the velocity autocorrelation function shows a broad maximum in the frequency region ω=0.25(k_{B}Tℏ). The shape of the Van Hove function G_{s}(r, t) attains a maximum departure from a Gaussian at about t=3.0×10^{12} sec and becomes a Gaussian again at about 10^{11} sec. The Van Hove function G_{d}(r, t) has been compared with the convolution approximation of Vineyard, showing that this approximation gives a too rapid decay of G_{d}(r, t) with time. A delayedconvolution approximation has been suggested which gives a better fit with G_{d}(r, t) this delayed convolution makes G_{d}(r, t) decay as t^{4} at short times and as t at long times.
 Publication:

Physical Review
 Pub Date:
 October 1964
 DOI:
 10.1103/PhysRev.136.A405
 Bibcode:
 1964PhRv..136..405R