Correlations in the Motion of Atoms in Liquid Argon

✍ Scribed by Rahman, A.

• Book ID: 117990980
• Publisher: The American Physical Society
• Year: 1964
• Tongue: English
• Weight: 698 KB
• Volume: 136
• Category: Article
• ISSN: 0031-899X
• DOI: 10.1103/physrev.136.a405

✦ Synopsis

A system of 864 particles interacting with a I.ennard-Jones 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 '. The pair-correlation function and the constant of self-di6usion 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 &o = 0.25 (h&T/h). The shape of the Van Hove function G, (r, t) attains a maximum departure from a Gaussian at about s=3 0.

X10 "sec and becomes a Gaussian again at about 10 "sec.The Van Hove function Gg(r, t) has been com- pared with the convolution approximation of Vineyard, showing that this approximation gives a too rapid decay of Gd, (r,t) with time. A delayed-convolution approximation has been suggested which gives a better 6t with Gz(r, I); this delayed convolution makes Gz(r, t} decay as t4 at short times and as I at long times.