Configuration interaction studies on the electronic states of the CUO molecule

Abstract

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′.

Keywords:

• actinide molecules

Acknowledgements

We thank Drs Jun Li and Anne McCoy for several useful discussions and help with this work. We thank the Ohio Supercomputer Center for a grant of computer time. This work was supported by grant DE-FG02-01ER15230 from the US Department of Energy SciDAC program. We also wish to acknowledge Dr H.F. Schaefer for all his group's long-time work to develop and thoroughly test new quantum chemistry methods.