Pseudopotential in the study of phonon dynamics of Pd-based metallic glasses

Abstract

The phonon dynamics of Pd35Zr65 and Pd80Si20 two non-crystalline systems have been studied in terms of the eigen frequencies of the localized collective excitations using model potential formalism. The pair potential and pair correlation function are obtained in Wills–Harrison (WH) form from the well recognized model potential of Gajjar et al. The phonon dispersion curves are computed from the three approaches proposed by Hubbard–Beeby (HB), Takeno–Goda (TG) and Bhatia–Singh (BS). Various elastic and thermodynamic properties have been studied from the elastic limit of the dispersion relations. The advanced local field correction function due to Sarkar et al. is used for the first time to include the influence of exchange and correlation on the aforesaid properties. The ratio (r2/r1) of the position of the second peak (r2) to that of the first peak (r1) of g(r) for both metallic glasses is close to the c/a ratio in close-packed hexagonal structure. Qualitatively, the phonon dispersion curves (PDC) computed from the BS approach are found to be better than HB and TG approaches.