An ab initio study of self-trapped excitons in α-quartz

A study was conducted on the energetics and structures of three different self-trapped exciton (STE) structures for quartz, which were predicted by plane-wave density functional theory (DFT) calculations. The STE-Si state was found to be stable in cluster calculations using UHF, and in a supercell calculation using plane-wave DFT. This structure was very near a curve crossing of the triplet and singlet surfaces, and may correspond to a nonradiative transition to the ground state.