A molecular dynamics study of structure and dynamics in high-density liquids

By means of molecular dynamics simulations we have investigated increasing configurational ordering and decreasing particle mobility with increasing density ρ of a two-dimensional equilibrated liquid composed of soft discs. An equaltime correlation function h (3) 2 (0) which includes three-body, as well as two-body, correlations is introduced as a measure of structural order; this function is related to the dipole-induced-dipole equal-time correlation function h (4) 2 (0), and its sensitivity to structural order in the liquid is associated with the cancellation effect, the cancellation of the positive contribution of the two-body correlations by the negative contribution of the three-body correlations. The analogous time-dependent correlation function h (3) 2 (t) is also studied. The possible implications of these results for the study of supercooled liquids and glasses is discussed.