Simple nonempirical calculations of the zero-field splitting in transition metal systems: I. The Ni(II)-Water complexes

Abstract

A simple nonempirical scheme is presented for calculating the splittings of ground state multiplets (the zero‐field splitting) in transition metal complexes. The method employs single reference, single excitation CI calculations based on open‐shell RHF. The spin–orbit coupling is described using an effective one‐electron, one‐center operators. The method is applied to the triplet state Ni(II) complexes with one to six water molecules. The validity of the second‐order perturbation theory approach and of the spin‐Hamiltonian formalism is found to be limited to slightly distorted octahedral systems. Generally, small changes in the geometries of the complexes are found to cause substantial variations of the splitting pattern.