The zero-field-splitting (ZFS) parameters D, a, and F for ${\mathrm{Cr}}^{2+}$ ions in GaAs are studied by a molecular-orbital treatment. Viccaro, Sundaram, and Sharma’s procedure is adopted in the study, taking into account all the excited spin triplets. The charge-transfer effect is shown to be significant, and the spin triplets are found to make an important contribution to ZFS. The results are compared with the previous available calculations in this system. Suggestions for future improvements are indicated.

• Received 17 January 1995

DOI:https://doi.org/10.1103/PhysRevB.51.14176