Study of collective dynamics of a non-crystalline aluminum–nickel binary alloy using pseudopotential theory

Abstract

The phonon dynamics of a transition metal–aluminum alloy, i.e. the Al0.75Ni0.25 binary non-crystalline system, has been studied in terms of the eigenfrequencies of the localized collective excitations using model potential formalism. The self-consistent phonon scheme given by Takeno and Goda, involving multiple scattering and phonon eigenfrequencies that are expressed in terms of many-body correlation functions of atoms as well as of interatomic potential in the solids, has been used to generate the collective modes in the non-crystalline Al0.75Ni0.25 alloy. The pair potential is obtained in Wills Harrison (WH) form from the well-recognized model potential of Ashcroft as a test case. The local field correlation functions due to Hartree (H), Taylor (T), Ichimaru–Utsumi (IU), Sarkar et al (S) and Farid (F) are used to investigate the influence of the screening effects on the vibrational properties. Results for the bulk modulus BT are obtained using the aforesaid local field correction functions. The results for the Shear modulus (C′), deviation from Cauchy's relation, Poisson's ratio (σ), Young modulus (Y), propagation velocity of elastic waves and phonon dispersion curves using model potential are reported here and good agreement with available experimental results was achieved.