Paramagnetic resonance hyperfine structure of hexachloroprotactinate(IV).

Abstract

Dirac scattered-wave calculations are presented for the ${\mathrm{PaCl}}_{6}^{2\mathrm{\ensuremath{-}}}$ cluster that models the ${\mathrm{Pa}}^{4+}$ impurity site in the octahedral ${\mathrm{Cs}}_{2}$${\mathrm{ZrCl}}_{6}$ lattice. The calculations predict a ${\ensuremath{\Gamma}}_{7u}$ ground state, and show fairly good agreement with the observed g tensor, $^{231}\mathrm{Pa}$ hyperfine interactions, and crystal-field splittings. The Zeeman and $^{231}\mathrm{Pa}$ hyperfine interactions are isotropic, arising from the large orbital contributions to the magnetic moment of the ground Kramers doublet. The amount of covalency is predicted to be about 3%, and the largest contribution to covalency comes from the chlorine 3${d}_{5/2}$ spinors (\ensuremath{\sim}2%).