Optical Absorption and Electronic Excitations in Hydrogenated Silicon Clusters

The study of electronic excitations in hydrogen terminated silicon clusters is important for understanding the optical properties of confined systems such as quantum dots and porous silicon. Here we calculate the excitation energies and absorption spectra for SinHm clusters using linear response theory within the time-dependent local density approximation (TDLDA). We find the computed excitation energies and photoabsorption gaps agree with available experimental data. The TDLDA optical absorption spectra exhibit a substantial blue shift with respect to the spectra calculated within the timeindependent local density approximation. This trend is consistent with other theoretical calculations for excited state properties, such as the Bethe-Salpeter technique.