Rajni Tyagi

Configuration interaction studies on the electronic states of the CUO molecule

Relativistic multireference configuration interaction calculations are carried out on the low-lying electronic states of the CUO molecule at linear geometries. The results of these and previous CUO calculations are discussed on the basis of the natures of these states and the advantages and disadvantages of different methods of computing electronic structure. We find the state, at its minimum geometry, to be 0.17 eV lower then the 3Φ2 state at its minimum energy geometry. The principal term of the state is 82.1% of the wave function with no large secondary terms. The principal term of the 3Φ2 state is 70.8% of the wave function with a secondary 3Δ2 term being 11.6% of the wave function. Calculations on CUO(Ar) at previously optimised geometries give the lowest state as 1 A′.

Electronic Spectrum of the UO and UO+ Molecules

Electronic theory calculations are applied to the study of the UO molecule and the UO(+) ion. Relativistic effective core potentials are used along with the accompanying valence spin-orbit operators. Polarized double-ς and triple-ς basis sets are used. Molecular orbitals are obtained from state-averaged multiconfiguration self-consistent field calculations and then used in multireference spin-orbit configuration interaction calculations with a number of millions of terms. The ground state of UO has open shells of 5f(3)7s(1), angular momentum Ω = 4, and a spin-orbit-induced avoided crossing near the equilibrium internuclear distance. Many UO excited states are studied with rotational constants, intensities, and experimental comparisons. The ground state of UO(+) is of 5f(3) nature with Ω = 9/2. Many UO(+) excited states are also studied. The open-shell nature of both UO and UO(+) leads to many low-lying excited states.