THEORETICAL-STUDY OF THE SPECTRA OF CUH AND CUD

The electronic states of CuH correlating with the two lowest dissociation channels have been studied by ab initio methods. Potential energy curves, electric dipole (transition) moments, and spin-orbit coupling matrix elements are evaluated using correlated wave functions determined from the (relativistic) no-pair equation. The excited states of CuH and CuD cannot be characterized as pure spin states. By including spin-orbit coupling in the calculations, a one to one correspondence can be established between experimentally known term energies and computed level positions. The A 1-SIGMA+ and B 3-PI-0+ states results from different linear combinations of 1 1-SIGMA+ and 1 3-PI-0+. The 3-PI state is found to have an inverted fine-structure pattern in contradiction to earlier assumptions. The experimentally known C 1 and c 1 states originate from admixtures of 1 3-DELTA and 1 1-PI. The large coupling between LS states explains the intensity of the otherwise forbidden transitions from 3-PI and 3-DELTA to the ground state. Among the states predicted from the present analysis is a low-lying 3-SIGMA+ state which may be responsible for the bands observed in the red region.