Large vacancy clusters, or voids, formed during crystal growth have been reported in Ge. The divacancy is a precursor to such clusters, and is believed to be stable up to 150 or 180 °C. It is also believed to form in Ge irradiated at room temperature where single vacancies are mobile. Density functional theory (DFT) cluster calculations have been performed to calculate the energy barriers for migration and dissociation of the divacancy. We find that the binding energy in the neutral charge state is ~1.5 eV and increases for negatively charged states. The migration energies were found to vary from 1.0 to 1.3 eV from the singly positive to the doubly negative charge states. These results line up well with an estimate of a migration barrier of 1.0 eV for the divacancy from experimental data. Therefore, we conclude that the divacancy in germanium will anneal by migration to trapping centers. ; Large vacancy clusters, or voids, formed during crystal growth have been reported in Ge. The divacancy is a precursor to such clusters, and is believed to be stable up to 150 or 180 °C. It is also believed to form in Ge irradiated at room temperature where single vacancies are mobile. Density functional theory (DFT) cluster calculations have been performed to calculate the energy barriers for migration and dissociation of the divacancy. We find that the binding energy in the neutral charge state is ~1.5 eV and increases for negatively charged states. The migration energies were found to vary from 1.0 to 1.3 eV from the singly positive to the doubly negative charge states. These results line up well with an estimate of a migration barrier of 1.0 eV for the divacancy from experimental data. Therefore, we conclude that the divacancy in germanium will anneal by migration to trapping centers.