MONTE-CARLO SIMULATION OF AMORPHOUS SYSTEMS WITH THE FRAGMENT SELF-CONSISTENT-FIELD METHOD

We present an overview on the application of our semiempirical 'neglec t of diatomic differential overlap fragment self-consistent field' met hod to the Monte Carlo simulation of amorphous carbon and silicon. The covalent model is partitioned into a relatively small subsystem treat ed at the conventional molecular orbital level and an environment pert urbed 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-consi stent 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 ve rsion of the fragment self-consistent field method has been developed. Radial and angular distribution functions, obtained for amorphous sil icon, are in good agreement with experiment. We calculated the same qu antities for amorphous carbon with a hypothetical 100% sp(3) hybridiza tion, but these cannot be compared directly to experiment. (C) 1997 El sevier Science B.V.