Theoretical evaluation of the dynamic properties of amorphous selenium

Abstract

The phonon frequencies of amorphous Se are calculated according to Bhatia-Singh's method assuming the electronic contribution to the bulk modulus is zero. These longitudinal phonon frequencies are used to evaluate the dynamic structure factor in the viscoelastic approximation. It is found that the dynamic structure factor of Se exhibits characteristics similar to that of Al and Rb. The current correlation function J_L(κ, ω) and S(κ, ω) are calculated for six typical momentum vectors. ω_max values are obtained from the computed J_L(κ, ω) correlation functions. The ω_max(κ) versus k plots give a maximum midway between zero and the second peak position of S(κ). S(κ, ω) versusω at fixed values of κ follows the predictions made by Egelstaff. At large κ, the S(κ, ω) gives a Lorentzian single-peaked curve resembling that of a perfect gas. It is found that the dynamic structure factor of amorphous Se resembles that of liquid metals like Al and Rb.