Elastic constants and collective modes in liquid transition metals: illustrating typically for iron and nickel

Abstract

The Wills-Harrison potential function developed to take into consideration the s-d hybridization in transition metals has been used for investigating the dynamic properties of Fe and Ni. These potentials along with respective radial distribution function have been used to evaluate the phonon frequencies in these liquid metals. The ω_L(k) and ω_T(k), the longitudinal and transverse phonon frequencies, respectively, have been used to evaluate the elastic constants. They have also been calculated from I₁ and I₂ integrals of Schofield. These computed elastic constants have been found to be consistent with each other. From the computed value of C₁₁, the compressibility was evaluated and was found to be in good agreement with experiment. The auto-correlation function, ψ(t), has been evaluated and the large negative region in ψ(t) versus t graph clearly indicated the caging effect and, hence, an effective mass concept was used in the evaluation of phonon frequencies. The characteristic frequency has been calculated from power spectrum. This value is compared with the value obtained from Debye's T³ law and also by other methods. The various frequency values are found to be close to each other in both metals.