RESONANCES AND BOUND ROVIBRATIONAL LEVELS IN THE INTERACTING X, A, C, AND D STATES OF HEH, HED, (HEH)-HE-3, AND (HED)-HE-3

Potential energy curves are calculated for the ten lowest states in HeH which correlate with the hydrogen asymptote in the n = 1, 2, 3 occupation; these are X, A, C, D, 5 2-SIGMA+, 6 2-SIGMA+, and B, E, 3 2II as well as the 1 2-DELTA states. Multireference configuration interaction calculations are employed thereby in an atomic orbital (AO) basis of contracted Gaussians. Extensive calculations of the partial/partial-R, partial-2/partial-R2, L(x), and L2 matrix elements are carried out to account explicity for the effects beyond the Born-Oppenheimer approximation. The positions of rovibrational levels are thereby determined in pairwise close-coupling calculations for the X / A and C / D states of 2-SIGMA+ symmetry for the four isotopomers 4HeH, 3HeH, 4HeD, and 3HeD. Radial, angular, and mass polarization corrections affect the A and C states differently, so that the A-C energy gap increases by 39 cm-1 in 3HeD and by 53 cm-1 in HeH upon introduction of these terms, e.g., whereby the contribution of the mass polarization is by far the smallest. By employing a two-parameter correction function to the calculated electronic potential energy and making use of the calculated non-Born-Oppenheimer terms, a large number of levels for the A, C, and D states as a function of (v,J) quantum numbers are computed which agree with those, which are experimentally available for the C-A and D-A transitions within wave number accuracy.