The electronic structure of ${\mathrm{Cr}}^{3+}$ dimers in ${\mathrm{LiNbO}}_3$ was calculated under the actual site symmetry ${\mathit{C}}_3$ with the spin-polarized self-consistent-charge discrete-variational ${\mathit{X}}_{\mathrm{\alpha }}$ method. The calculated results support the suggestion that substitution of ${\mathrm{Cr}}^{3+}$ ions for ${\mathrm{Nb}}^{5+}$ and for ${\mathrm{Li}}^{+}$ ions leads to the formation of dimerlike pairs in ${\mathrm{LiNbO}}_3$.

• Received 20 April 1993

DOI:https://doi.org/10.1103/PhysRevB.48.4868