Ligand positions and crystal field parameters for Cr3+at tetragonal sites ion MgO

Ligand positions for Cr 3+ at tetragonal sites in MgO are calculated from a lattice relaxation model. Using these ligand positions in conjunction with the parameters previously derived from the Cr 3+ :Al 2 O 3 system, the author obtains the tetragonal crystal field parameters and the splittings of the low-lying energy levels for the present Cr 3+ system. These results are compared with some experimental data and some fallacious calculations found in the literature are pointed out.