Relativistic molecular orbital study of the optical and magnetic properties of hexachloro protactinate (IV): PaCl₆^2-

Our ab initio all-electron Dirac-Fock and the corresponding nonrelativistic limit calculations performed at four Pa-Cl bond distances yield for octahedral Pa Cl6 2- the optimized Pa-Cl bond distances of 2.758 and 2.771 Å, respectively. Dirac scattered wave and its nonrelativistic limit calculations are performed at the optimized Pa-Cl bond distances using a first-order perturbation procedure to obtain the molecular g and hyperfine tensors for the octahedral anion Pa Cl6 2-. The calculated Zeeman and Pa231 hyperfine interactions are in fairly good agreement with the electron paramagnetic resonance and electron nuclear double resonance values of the Pa4+ impurity site in the octahedral Cs2 Zr Cl6 lattice. The calculated relativistic transition energies of the 5f→5f and 5f→6d absorption bands are also in good agreement with the experimental results.