Si-H clusters, defects, and hydrogenated silicon

All-electron density functional methods have been used to calculate the structures and energies of silicon/hydrogen clusters with up to 148 atoms. Vibration frequencies are calculated for those clusters with less than 75 atoms. In addition to hydrogen-terminated clusters based on the structures of bulk Si, we study structures involving vacancies. divacancies, and additional H atoms. The results are compared with earlier work and provide vibration fingerprints that should aid the interpretation of measurements (such as infrared spectra) of hydrogenated crystalline and amorphous silicon.