Statistical geometry of some dense random packing of hard spheres model structures: I. Description of local order

Abstract

The sensitivity of some parameters describing the short range order of amorphous model structures is investigated. Two binary dense random packing of hard spheres models built with and without the constraint that metalloids may not be in hard contact are compared. Besides the partial pair correlation functions, Voronoi polyhedron volumes and conventional coordination numbers defined by a cut-off distance, a new coordination number defined by the pyramidal volume contributions of the generalized Voronoi polyhedron is introduced and tested. Because this coordination number is real and it changes continuously with any continuous variation of the structure, it is more adequate to describe minor differences of the local order than the usual integer coordination numbers. It is shown that the use of integer coordination numbers leads to the overestimation of the disorder of the structure.