Self Atom-Atom Empirical Potentials for the Static and Dynamic Simulation of Condensed Phases

Abstract

The self-recognition and subsequent condensation of organic molecules into macroscopic aggregates gives rise to a rich and diverse phase behaviour. The ultimate state, at very low temperature, is ideally a pure, perfectly ordered crystal: as temperature rises, the substance may proceed to several kinds of partly disordered systems. Loss of one-or two-dimensional order produces rotator phases, plastic crystals, then liquid crystals, while total absence of order, still without molecular mobility, is proper of the glass state. After melting, liquids in the proximity of their freezing point may preserve some memory of the more ordered states, while, on increasing the temperature, molecular correlation decreases until the molecular assembly assumes the fully isotropic aspect which, in a structural and thermodynamic sense, characterizes the true liquid state.