<i>A</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> studies of the electronic structrue of UF6, UF6+, and UF−6 using relativistic effective core potentials

A b initio calculations are performed on the electronic states of UF6, UF6+, and UF−6 using a relativistic effective core potential (ECP) for uranium and a nonrelativistic ECP for fluorine. In most of the calculations 56 valence electrons are treated explicitly using a contracted [3s3p2d2f/2s2p] Gaussian basis. Various ECP’s were explored, but all yield an overall charge density of U+2.4 (F−0.4)6. The bonding in the ground state of UF6 is discussed. SCF and CI calculations on UF6+ are compared with the experimental photoelectron spectrum and with previous scattered-wave calculations. The role of spin–orbit coupling in the states of UF6+ and UF6− is discussed. The calculated electron affinity of UF6 (7.1 eV) is considerably larger than the current experimental estimates, but the relative energies of the states of UF6− are in excellent agreement (0.1–0.2 eV) with experiment.