title: Multiconfiguration Dirac-Hartree-Fock adjusted energy-consistent pseudopotential for uranium: spin-orbit configuration interaction and Fock-space coupled-cluster study of U4+ and U5+.
abstract: In order to assess the accuracy of a recently adjusted relativistic energy-consistent small-core pseudopotential for uranium, the U(5+) (5f(1) subconfiguration) spin-orbit splitting as well as the fine structure of the U(4+) (5f(2) subconfiguration) spectrum have been calculated. The pseudopotential has been adjusted to four-component all-electron data, i.e., at the multiconfiguration Dirac-Hartree-Fock level using the Dirac-Coulomb Hamiltonian with a Fermi nucleus charge distribution and perturbatively including the Breit interaction. Its performance in a dressed effective Hamiltonian spin-orbit configuration interaction framework is compared to that of an older scalar-relativistic Wood-Boring adjusted pseudopotential, supplemented by a valence spin-orbit term, as well as to all-electron calculations using the Douglas-Kroll-Hess Hamiltonian. Electron correlation is accounted for by the multireference configuration interaction method with and without the Davidson correction and with different frozen-orbital spaces. Our best calculations show satisfactory agreement with experimental data; i.e., the mean absolute (relative) deviations amount to 183 (2.4%) and 948 cm(-1) (5.1%) for the U(5+) and the U(4+) fine-structure energy levels, respectively. Even better agreement, comparable to the one for rigorous highly correlated four-component all-electron data, is obtained in intermediate Hamiltonian Fock-space coupled-cluster calculations applying the new pseudopotential.
authors: Institut für Theoretische Chemie, Universität zu Köln, Greinstrasse 4, D-50939 Köln, Germany. anna.weigand@uni-koeln.de
authors: Anna
authors: A
authors: Weigand
authors: Xiaoyan
authors: X
authors: Cao
authors: Valérie
authors: V
authors: Vallet
authors: Jean-Pierre
authors: JP
authors: Flament
authors: Michael
authors: M
authors: Dolg