First-principles derivation of structural anomalies in hcp Zn and hcp Fe under pressure

Abstract

A procedure for finding the equilibrium states of a hep structure under pressure from minima of the Gibbs free energy using first-principles electronic theory has confirmed the existence of structural anomalies in hep Zn and hep Fe. Calculations of elastic constants as functions of pressure then show that the anomalies are large effects which cover a substantial range of pressure. These calculations permit reinterpretation of the experimental data to show that the structural anomaly, although small, can be seen in the data. These calculations contradict a recent first-principles calculation that found that the structural anomaly in hcp Zn disappeared when a large number of k-points were used in the Brillouin zone integrations.