A system of 864 particles interacting with a Lennard-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 . The pair-correlation function and the constant of self-diffusion 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 . The shape of the Van Hove function attains a maximum departure from a Gaussian at about sec and becomes a Gaussian again at about sec. The Van Hove function has been compared with the convolution approximation of Vineyard, showing that this approximation gives a too rapid decay of with time. A delayed-convolution approximation has been suggested which gives a better fit with ; this delayed convolution makes decay as at short times and as at long times.
- Received 6 May 1964
- Published in the issue dated October 1964
© 1964 The American Physical Society