The theory of spin correlated crystal fields

Effective operators of the spin correlated crystal field have been derived using a second order perturbation mechanism which couples an exchange interaction with the crystal field. We have taken into account the effect of excited configurations involving np and np orbitals. Relativistic wavefunctions have been used to calculate radial integrals. Second order degenerate perturbation theory has been employed, in projector form, to find an equivalent operator which acts only within the ground manifold of total angular momentum.