15min:

F. MICHAEL DOLG AND XIAOYAN CAO, Institut für Theoretische Chemie, Universität zu Köln, Greinstr. 4, D-50939 Köln, Germany..

Large-scale multireference configuration-interaction (MRCI) calculations using the all-electron scalar-relativistic Douglas-Kroll-Hess (DKH) Hamiltonian, as well as a relativistic energy-consistent small-core pseudopotential (SPP) for uranium, have been performed to study the low-lying electronic S states of uranium monohydride UH with term energies below 0.5 eV. After taking spin-orbit effects into account both DKH/MRCI and SPP/MRCI calculations predict a ⁴I_9/2 ground state. The calculated ground state molecular constants of both approaches show a good agreement with each other (MRCI+Q, DKH: Re=2.021 Å, _e=1483 cm^-1, D_e=2.79 eV; SPP: R_e=2.011 Å, _e=1497 cm^-1, D_e=2.85 eV), as well as with available experimental data ( _e=1424 cm^-1 in argon matrix).