EVALUATION OF GRUNEISEN PARAMETERS, 3RD-ORDER ELASTIC-CONSTANTS, AND OTHER ASSOCIATED PROPERTIES OF AMORPHOUS AS

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 an d transverse Gruneisen parameters, which are related to third-order el astic constants (TOEC), have been calculated. A method has been descri bed to evaluate the third-order elastic constants. Shiren's nonlinear parameter has been used to calculate the third-order elastic constant C-155 which is found robe in satisfactory agreement with experiment. N ath-Smith-DeLaunay's equation has been used to compute the position of the absorption band and this is compared with that obtained from BS p arameters. There is good agreement between the two values. The gamma(g )(el) calculated from Nath-Smith-DeLaunay's equation gives good result in agreement with that calculated from gamma(g)(L) and gamma(g)(T), w hich are obtained from Schofield's and BS equations. Phonon frequencie s have been evaluated through the BS method. It is found that in the c ase of omega(L)(k) the collective nature of excitons persists up to la rge wave vector k.