Volume dependent lattice dynamics of solid argon A pseudo‐harmonic approach

Abstract

AbstractThe volume dependent lattice dynamics of solid argon is calculated using a pseudo‐harmonic approach. The volume dependence of the elastic constants, from which the lattice dynamical model parameters are deduced, is obtained by relating the elastic constants to a m‐n pair potential of the Mie‐Lennard‐Jones type. The volume dependence of the phonon states is used to obtain the first and second Grüneisen parameters and constants. The thermal expansion coefficient is then calculated from the Grüneisen parameters in the quasi‐harmonic approximation. Finally, the Mie‐Grüneisen equation of state and the Lindemann melting criterion are combined to predict the melting curve of argon. Reasonable agreement is obtained between the calculated and experimental results.