THEORY OF STRUCTURE OF TETRAHEDRALLY BONDED AMORPHOUS SOLIDS

A theory is presented in which the radial distribution function (RDF) of a tetrahedrally bonded solids is taken to be the sum of n-bond neighbor distributions Jn(r). The Jn(r) are calculated, for n = 1-4, using parameters estimated from crystalline studies, and free parameters governing the dihedral angle distribution, ring statistics and bond-angle distortion. The accuracy of the theory is established by comparison with the results of structural models of amorphous Ge. Application of the theory to the structure of amorphous Ge accounts quantitatively for the experimental RDF out to a radius of 6 Å. Limits are placed on the dihedral angle distribution, indicating that staggered configurations are more probable than eclipsed configurations. In general, the location of the third peak in the RDF is found to correlate with the fraction of staggered configurations. © 1978.