Evaluation of Gruneisen parameters, third-order elastic constants, and other associated properties of amorphous As

Abstract

Pressure derivatives of second-order elastic constants of amorphous As have been derived through the use of Schofield's equations and Bhatia-Singh's (BS) parameters. By using these equations the longitudinal and transverse Gruneisen parameters, which are related to third-order elastic constants (TOEC), have been calculated. A method has been described to evaluate the third-order elastic constants. Shiren's nonlinear parameter has been used to calculate the third-order elastic constant C₁₅₅ which is found to be in satisfactory agreement with experiment. Nath-Smith-DeLaunay's equation has been used to compute the position of the absorption band and this is compared with that obtained from BS parameters. There is good agreement between the two values. The γ_g^el calculated from Nath-Smith-DeLaunay's equation gives good result in agreement with that calculated from γ_g^L and γ_g^T, which are obtained from Schofield's and BS equations. Phonon frequencies have been evaluated through the BS method. It is found that in the case of ω_L(k) the collective nature of excitons persists up to large wave vector k.