Universal features of the equation of state of metals

TLDR

The anharmonicity of crystals, quantified by the parameter η, is relevant to the equation of state of metals. The authors present a simple formula that predicts the zero‑temperature derivative of bulk modulus with respect to pressure. The study demonstrates that the zero‑temperature equation of state of metals can be accurately predicted from zero‑pressure data, that appropriately scaled pressure‑volume data follow a universal relation, and that the anharmonicity parameter η is essential for this prediction, confirming a universal scaling of total‑binding‑energy versus separation.

Abstract

The zero-temperature equation of state of metals, in the absence of phase transitions, is shown to be accurately predicted from zero-pressure data. Upon appropriate scaling of experimental pressure-volume data a simple universal relation is found. These results provide further experimental confirmation of the recent observation that the total-binding-energy---versus---separation relations for metals obey a universal scaling relation. Important to our results is a parameter $\ensuremath{\eta}$, which is a measure of the anharmonicity of a crystal. This parameter is shown to be essential in predicting the equation of state. A simple formula is given which predicts the zero-temperature derivative of the bulk modulus with respect to pressure.