First principles theory of the EPR g-tensor in solids: defects in quartz

A theory for the reliable prediction of the EPR g-tensor for paramagnetic defects in solids is presented. It is based on density functional theory and on the gauge including projector augmented wave (GIPAW) approach to the calculation of all-electron magnetic response. The method is validated by comparison with existing quantum chemical and experimental data for a selection of diatomic radicals. We thenperform the first prediction of EPR ${\rm g} $-tensors in the solid state and find the results to be in excellent agreement with experiment for the $E'_1$ and substitutional P defect centers in quartz.