Topological disorder in sillium: A statistical approach

The Sillium model is an idealized representation of the forces/energies associated with shared covalent tetrahedral bonds. As such it is useful in studie of three-dimensional random networks representing the structure of amorphous materials. States of the system can be created by randomization and annealing, using a simple bond-switching process. To investigate this procedure in detail, an analytical model of the effects of bond-switching is developed, based on statistical mechanics and rate equations. Simulations of randomization, heating and annealing of the network are carried out, enabling the kinetics and equilibrium properties of topological disorder to be studied. From a comparison of simulations and analytical models, randomization can be understood as a dynamical process with variable switch energy; also differences between near-crystalline and amorphous states can be interpreted in terms of entropy and energy landscape, and topological transitions such as network entanglement can be understood. © 1990.