Effect of three-body forces on the static and dynamic correlation functions of a model liquid

Molecular-dynamics calculations for a three-dimensional model liquid of 108 particles were performed to probe pair and triplet interactions. The triplet potential was assumed to have the Axilrod-Teller form, while the pair interaction was represented by the Lennard-Jones (12-6) potential. The computations were done to simulate liquid Ar at densities between 1.3 and 1.5 g/${\mathrm{cm}}^3$ and at a temperature of 100 K. The findings of Schommers for a two-dimensional model liquid are partly supported. The details of our calculations indicate, however, that the three-dimensional system exhibits a different behavior compared to that of the two-dimensional model. In the three-dimensional system both the static and dynamic correlation functions are affected by the triplet interactions. The influence of the triplet interaction on the time-dependent correlations is not as pronounced as in the two-dimensional system. For higher densities the effect of the Axilrod-Teller potential on the correlation functions diminishes, whereas the effect on the energy does not.