State mixing and the preferred jahn-teller coupling in cubic fx systems

Abstract

The effect of the inclusion of state mixing is examined for the calculation of the Jahn-Teller coupling constants of the two Γ 8 states of f 1 systems in O h symmetry, both ML 6 and ML 8 species being considered. For the values of the spin-orbit coupling constants and ligand-field splitting parameters usually encountered, the results differ significantly from the strong-field limit values, but only slightly from those of the weak-field limit. For ML 6 systems the available estimates for the e λ and ∂ e λ ∂R parameters of the angular overlap model, together with the appropriate force-constant ratios, predict dominant coupling to the ϵ g mode for the Γ 8( 2 F 5 2 : 2 T 2u) level, whilst coupling to the τ 2g mode should prevail for the Γ 8( 2 F 7 2 : 2 T 1u) state. For ML 8 species the calculations similarly lead to the expectation of predominant τ 2g(δ) coupling for Γ 8( 2 F 5 2 : 2 T 1u), with prevailing ϵ g coupling for Γ 8 ( 2 F 7 2 : 2 T 2u). The results suggest the general adequacy of the weak-field limit results for cubic f x systems and, as an example, the T 1 and T 2 states for 3 H 4 of f 2, O h ML 6, systems are thus briefly treated.