Schlafli cluster topological analysis of medium range order in paracrystalline amorphous semiconductor models

We show that topologically crystalline regions in computer models of amorph ous materials can be identified by examining the Schlafli cluster associate d with each atom. The Schlafli cluster contains those atoms that define the Schlafli circuit symbol. Different crystalline topologies that have the sa me Schlafli circuit symbol may be distinguished by considering the number o f atoms in the Schlafli cluster. The diameter of the cubic diamond Schlafli cluster in Ge is similar to 0.9 nm, which is typical of the shorter length scales associated with medium range order in amorphous materials. Regions of connected identical Schlafli clusters can be readily identified in model s and their combined size provides an intrinsic length scale for describing the medium range order. (C) 2000 Elsevier Science B.V. All rights reserved .