Investigations of zero-field splitting and defect structure for the tetragonal Fe3+K–OI center in KTaO3 crystal Original Research Article

By using the defect structure data (characterized by the coordinates of impurity center) obtained from the shell model and the density functional theory in the generalized gradient approximation (GGA) corresponding to two supercell sizes, the zero-field splitting D of the tetragonal View the MathML sourceFeK3+–OI center in KTaO3 crystal is calculated from the high-order perturbation formula based on the dominant spin–orbit coupling mechanism. The calculated results suggest that the sign of zero-field splitting D is negative and the defect structure data obtained from GGA method are more reasonable. Compared with that corresponding to the smaller supercell size, the calculated D value based on the GGA coordinates corresponding to the larger supercell size is closer to the observed value, suggesting that the GGA coordinates obtained from the larger supercell size are more accurate.