Effective pair potential and phonon spectra in liquid Se1−x Te x alloys with the nonmetal-metal transition

Abstract

Using experimental values of the structure factor of liquid Se1−xTex(x=0.0, 0.6, 0.7, 0.8, 1.0.) alloys measured by Takedaet al., the potential functions at different compositions are derived from Rao-Joarder's equation. From the change of the shape of the potential function at different compositions, we can infer that whenx is between 0.7 and 0.8 the nonmetal-metal transition occurs in this system. This is the first time to use the calculation of the potential function to find the NM-M transition Furthermore we give the longitudinal and transverse phonon frequencies by using Bhatia-Singh's model. Then the elastic constants are computed. Using the potential function, the characteristic frequency is obtained and compared with the average frequency, Debye frequency, and the maximum longitudinal frequency computed by other methods. Finally, we compare the sound velocities calculated from the elastic constants in the long-wave limit with corresponding experimental values.