Knowledge Bank

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 $\Lambda$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 $4$I$\mathrm{<mrow\; data-mjx-texclass="ORD">9<mrow\; data-mjx-texclass="ORD">/</mrow>2</mrow>}$ ground state. The calculated ground state molecular constants of both approaches show a good agreement with each other (MRCI+Q, DKH: Re=2.021 \AA, $\omega e$=1483 $\backslash wn$, D=2.79 eV; SPP: R=2.011 \AA, $\omega e$=1497 $\backslash wn$, D=2.85 eV), as well as with available experimental data ($\omega e$=1424 $\backslash wn$ in argon matrix).