Monte Carlo simulation of amorphous systems with the fragment self-consistent field method

Abstract

We present an overview on the application of our semiempirical ‘neglect of diatomic differential overlap fragment self-consistent field’ method to the Monte Carlo simulation of amorphous carbon and silicon. The covalent model is partitioned into a relatively small subsystem treated at the conventional molecular orbital level and an environment perturbed by the former. The wave function is expanded either on a Slater-type atomic orbital or on a hybrid orbital basis set, and a self-consistent field calculation is made for the subsystem in the field of the iteratively determined electronic distribution of the environment. For energy calculation of the infinite amorphous systems a Monte Carlo version of the fragment self-consistent field method has been developed. Radial and angular distribution functions, obtained for amorphous silicon, are in good agreement with experiment. We calculated the same quantities for amorphous carbon with a hypothetical 100% sp 3 hybridization, but these cannot be compared directly to experiment.