Crystal-field levels and magnetic susceptibility inPuO2

Ground-state electronic structure and crystal-field levels of ${\mathrm{PuO}}_2$ have been calculated by means of a symmetry constrained local density approximation to density-functional theory in terms of total energy differences. The calculated ${\Gamma }_1$ (ground state) to ${\Gamma }_4$ (first excited state) excitation energy of 99 meV is in reasonable agreement with the measured value 123 meV from inelastic-neutron-scattering experiments. The measured magnetic susceptibility has been analyzed and its discrepancy with neutron-scattering results is partially removed by the introduction of antiferromagnetic exchange enhancement.