COVALENCY EFFECTS IN TRIGONAL DISTORTION.
ISRAEL ATOMIC ENERGY COMMISSION YAVNE SOREQ RESEARCH ESTABLISHMENT
Pagination or Media Count:
The strength of the axial field, as derived from the splittings of the optical bands of paramagnetic metal ions in crystals of trigonal symmetry, fluctuates greatly from band to band. A qualitative explanation of the effect may be given by assuming that, in addition to the mostly positive trigonal field splitting parameter acting at the metal ions, there is also a larger and negative trigonal field splitting parameter acting on the molecular orbitals formed from the ligand orbitals. Covalency mixing results in an effective splitting parameter that differs for each configuration in the t3 and e2 subshell, written in the order of algebraically increasing splitting parameter. Of equivalent configurations, the one possessing greater interelectronic interaction energy is likely to have smaller covalency coupling and consequently the more positive trigonal field splitting parameter. These findings agree with the empirical data qualitatively however, the quantitative agreement is insufficient. Author