Paramagnetic susceptibilities and anisotropies of nickel(II) ions in ‘tetrahedral’ environments. Part I. General behaviour of a spin–triplet model

Abstract

The theoretical principal magnetic susceptibilities of ‘tetrahedral’ nickel(II) ions have been studied within a model incorporating a tetrahedral crystal field, a tetragonal angular distortion and anisotropic spin–orbit coupling. Wavefunctions of the ³F and ³P free-ion terms form the basis set. A crystal field (D_2d) point-charge calculation, parameterized by the radial integrals Dq and Cp, and θ, the angular distortion, is discussed and the irrelevance of the spherical harmonic Y₂⁰ in the potential is demonstrated. The magnetic behaviour of this model with respect to all parameters has been investigated. The present model predicts magnetic moments 0·5 B.M. higher than those of an earlier model in which the ³T₂ and ³A₂ cubic-field terms were omitted, so that previous estimates of spin–orbit coupling and reduction of orbital angular momentum and distortion were in error.