Universality relationships in condensed matter: Bulk modulus and sound velocity

Abstract
We present new forms for the bulk modulus and sound velocity of solids under compression, based on the universal equation of state of Vinet, Ferrante, Smith, and Rose. We then compare the Vinet et al. expressions with a number of bulk modulus formulas previously utilized in high-pressure studies. We demonstrate that this form yields a superior fit to experimental data to very high compressions, for a very wide range of solids. These solids cover the entire range of values of the pressure derivative of the bulk modulus which has been observed in high-pressure measurements.