COLLECTIVE EXCITATIONS IN A BINARY-LIQUID ALLOY

There have been many inelastic neutron scattering as well as theoretic al studies of monoatomic liquid metals, but there have been very few s tudies of metallic alloys. A new effective pair-potential for equiatom ic liquid Na-Cs alloy is computed treating the system as made up of ef fective atoms. This potential agrees closely to that obtained using pa rtial pair-potentials. The dispersion relations are computed using thi s potential: The longitudinal mode shows large oscillations depicting the collective excitations. The transverse mode does not show any osci llation. The collective excitations of longitudinal branch match quali tatively quite well with Neturon Inelastic Stattering (NIS) results. T he elastic part of the phonon dispersion curves provide sound velociti es and the value lies very close to experimental one. The elastic cons tants and Debye temperature of this alloy are calculated through the d erived sound velocities.