Lattice dynamics of face-centered-cubic metals using the ionic Morse potential immersed in the sea of free-electron gas

Abstract

Lattice vibrations in six face-centered-cubic metals (i.e., copper, silver, gold, lead, palladium, and nickel) are studied by computing phonon dispersion relations along the principal symmetry directions, and the Debye temperature (${\ensuremath{\Theta}}_{D}$), the mean-square displacement ($〈{u}^{2}〉$), the effective x-ray characteristic temperature (${\ensuremath{\Theta}}_{m}$), and the Debye-Waller factor exponent ($W$), as a function of absolute temperature ($T$). The model used for the present purpose is the ionic Morse potential immersed in a sea of free-electron gas. This scheme provides a new way to evaluate Morse-function parameters by including the effects of the conduction electrons in the metals. The computed results are found to be in excellent agreement with the available experimental observations for almost all the metals studied.