DYNAMIC CORRELATIONS AND PHONON-DISPERSION IN A LIQUID BINARY ALLOY

Theory of Brownian motion of particles in static harmonic well approximation is applied to study the vibrational dynamics of liquid NaxCs1-x (x = 0.5; 0.85) alloys. Dynamical variables like velocity autocorrelation function, power spectrum, and the mean square displacement are computed. The effective interatomic potential of the alloy used is obtained through the pair-potentials of individual components. The co-operative motion of atoms is described in terms of spectral functions of longitudinal current-current correlation functions which are obtained through the mean square displacement. These spectral functions of longitudinal current-current correlations are then used to get phonon dispersion in the alloy. The results are compared with the recently reported quasi-dispersion results of neutron inelastic scattering (NIS) experiments. Good qualitative agreement is observed.