title: Multireference configuration interaction calculations of the first six ionization potentials of the uranium atom.
abstract: The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set limit using new all-electron correlation consistent basis sets. The latter was carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons has been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. The final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV) and thus more reliable than the current experimental values of IP3 through IP6.
authors.affiliation: Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Bross
authors.affiliation: Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA.
authors.forename: Payal
authors.initials: P
authors.lastname: Parmar
authors.affiliation: Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA.
authors.forename: Kirk A
authors.initials: KA
authors.lastname: Peterson