Chain formation and the origin of structure in the Raman spectrum of a-SiSe₂

We have used a first-principles method based on the density functional theory to investigate the Raman spectrum of a-SiSe₂. By calculating vibrational frequencies and associated Raman intensities for a series of cluster models, we arrive at an interpretation of the observed spectrum that directly links spectral features to structural units in the glass. The results indicate that edge-sharing chains containing three tetrahedra are a dominant structural motif in the stoichiometric glass.