Bandwidths of octahedrally coordinated ${\mathrm{Ni}}^{2+}$ in ${\mathrm{Gd}}_3$${\mathrm{Ga}}_5$${\mathrm{O}}_{12}$ garnet

The spectroscopic properties of octahedrally coordinated ${\mathrm{Ni}}^{2+}$ ions in ${\mathrm{Gd}}_3$ ${\mathrm{Ga}}_5$ ${\mathrm{O}}_{12}$ garnet are described with a five-parameter model in the framework of the adiabatic approximation. The effect of spin-orbit coupling on the vibronic potentials due to the fully symmetric vibration is pointed out. Values of parameters useful for comparison with previous works, such as a pseudo-Huang-Rhys parameter or the ‘‘phonon’’ energies of the levels, are given.