Predicting the gas-liquid transition of mercury from interatomic many-body interaction

Abstract

A new cross-hierarchical equation of state for expanded fluid mercury is developed by combining quantum-chemical analysis of interatomic interactions and soft-sphere fluid variational approach. The theory incorporates ab initio diatomic potential energy curves and an additional many-body potential describing the associative interaction of an atom with its neighbouring atoms forming a local temporary cluster. The experimental gas-liquid coexistence curves are accurately reproduced without introducing empirical adjustable parameters. The gas-liquid transition is dominated by the many-body interaction, which becomes strongly attractive as the average coordination number increases and the local electronic states change from nonmetallic to metallic. © 2008 IOP Publishing Ltd.