Local symmetry of nitrogen pairs in GaP

We report an investigation of the stress-induced splitting pattern of ${\mathrm{NN}}_{\mathrm{i}}$ pairs in GaP. Analyzing the data in terms of stress-induced components and relative intensities, we deduce the local symmetry of pairs ranging from ${\mathrm{NN}}_1$ to ${\mathrm{NN}}_7$. With the exception of ${\mathrm{NN}}_1$, ${\mathrm{NN}}_3$, and ${\mathrm{NN}}_4$, we find results which cannot be directly accounted for in light of the standard assignment for pairs of substitutional nitrogen atoms.