Extended x-ray-absorption fine-structure Debye-Waller factors and vibrational density of states in amorphous arsenic

A connection between Raman intensities and the extended x-ray-absorption fine-structure (EXAFS) nearest-neighbor mean-square relative displacement ${\sigma }_R^2$, stressing the predominance of bond-compression mechanisms in depolarized Raman scattering, is tested in amorphous arsenic. Parameter-free relative densities of states, which enter ${\sigma }_R^2$ calculations, are obtained from the reduced Raman intensity and from neutron inelastic scattering data, in the framework of a nearest-neighbor central-force model. In both cases, the experimental temperature dependence of the EXAFS Debye-Waller thermal disorder parameter is well reproduced. The results are discussed in terms of Einstein and Debye models through a calculation of the negative moments of the relative density of states.