High-temperature properties of the fcc metallic crystals in anharmonic approximation

Abstract

The reduced second-order approximation of the self- consistent phonon theory was applied some years ago for cubic metallic crystals those interatomic were approximated by the Morse and Lennard-Jones pair potentials were generally obtained with the help of semi-classical method basin on the classical static relationships between ground- state properties of a crystal and its interatomic potential, and the zero-point vibrations were taken into account only by certain corrections to the experimental data. Moreover, the further self-consistent calculations were being carried out semi-analytically which required some simplifications. In this paper we can reject them because all essential calculations are being carried out numerically. In the studies at high-temperature properties of selected fcc metallic crystal we take as a model of interatomic interactions the Buckingham, Lennard-Jones and Morse pair potentials with the parameters determined self-consistently with the help of the experimental data for the zero-point lattice constant, cohesive energy and isothermal compressibility. Our new theoretical result for pressure variations of the limiting temperatures of dynamical and thermodynamical stability and for the stability criteria are collected and compared with available experimental data.