Structure simulation of amorphous monatomic and binary systems

Abstract

A simplified approach to computer simulation of amorphous structures by the dense random packing of hard spheres (DRPHS) has been developed and applied to amorphous Tb and TbFe 2. The computer algorithms devised are rapid and result in uniform, isotropic packing for both the monatomic as well as binary systems; in the latter case, small-atom drift toward the center of the cluster is reduced to the uncertainty in the random number generator. Energy relaxation has been performed using the first term in Keating's expression for the elastic energy; relaxation causes the peaks in the pair correlation functions to broaden, but their relative intensities (peak areas) remain essentially the same. In all cases investigated, the packing fractions are 2% (or less) smaller than those of Finney's ball bearing measurements, and the calculated densities are 13–23% lower than their crystalline counterparts. The pair correlation functions of the monatomic and binary models have been compared with X-ray results on CoP and neutron results on TbFe 2 and found to be in good agreement.