Sensitivity of liquid-state inherent structure to details of intermolecular forces

Abstract

Temperature dependence of short-range order has been systematically studied in two model atomic liquids, using molecular dynamics computer simulation linked to steepest-descent mapping of configurations onto potential minima. Owing primarily to differing attractive forces, the natural crystal structures differ for the two models (face-centered-cubic vs primitive hexagonal). Only one of these crystals is geometrically consistent with the number of particles (256) and boundary conditions (periodic, cubic cell) used for both. Nevertheless, both liquids were found to exhibit temperature dependence of short-range order arising solely from vibrational smearing of underlying temperature-independent inherent structure. The latter differs substantially for the two models, and in each case resembles a highly defective version of the corresponding crystal.