BASIS SET AND GAUGE DEPENDENCE OF ABINITIO RADIATIVE LIFETIMES FOR THE A 2-SIGMA+ STATE OF THE HF+ MOLECULE

The potential energy curves of the X 2Π and A 2Σ+ electronic states of the HF+ molecular ion are determined by CI expansions employing several one-particle Gaussian basis sets. The radiative lifetimes of the vibrational Born-Oppenheimer levels of the A state are then evaluated in both the length and velocity forms of the transition operator. With respect to improvements of the wavefunctions, the transition moments and lifetimes are found to be much more stable in the length gauge than in the velocity gauge. Thus the observed gauge disagreement of the computed observables is mainly ascribable to the inaccuracy of the velocity gauge transition moments and therefore the more commonly employed length gauge seems to be the preferred one in the present computational context. © 1990.