Elastic properties of amorphous selenium at high pressure

The elastic constants Cˡ and Cᵗ for amorphous Se have been measured as a function of hydrostatic pressure up to 16 Kbar. The isothermal bulk modulus KT is evaluated and found to exhibit a softening effect with increased pressure. The pressure dependence of KT is interpreted in terms of an interatomic potential composed of two terms; a Lennard-Jones term, and a phenomenologically introduced attractive term due to intrachain-interchain interaction. It is shown that this new potential predicts the well-known transition at 130 kbar and that KT derived from it agrees very well with the data. In the limit of zero pressure it appears that the Lennard-Jones term alone is sufficient to describe the elastic properties of α-Se.