Methodological Problems in the Calculations on Amorphous Hydrogenated Silicon, a-Si:H

摘要

Large silicon clusters (up to 230 atoms) with vacancies of different size were used to model the electronic structure of defects in amorphous silicon. We used a mechanical embedding technique, where a small core of atoms around a vacancy is surrounded by a larger number of bulk atoms. The electronic structure of the core was calculated with DFT methods, the bulk was treated with a semiempirical quantum chemical method. With this hybrid technique we investigated the structure of the cluster and ground and excited electronic states.