Multireference configuration interaction and quantum defect calculations on the Rydberg states of the BH molecule

Abstract

Configuration interaction calculations have been carried out on electronic states of BH and BH þ . The calculated spectroscopic constants are in good agreement with experimental data, where available. Quantum defect functions have been calculated from the ab initio potential energy curves of 4sÁ) and 4f( 3 Á) Rydberg states of BH, which may be used to generate all the Rydberg states of each series up to the ionization limit. Calculated vibrational autoionization widths for the Rydberg states are smaller than 0.5 cm À1 .

Theoretical study of nonadiabatic interactions, radiative lifetimes and predissociation lifetimes of excited states of BH

“…In the present work, the BH system is revisited, in work complementary to that of our previous report [29]. The lower-lying electronic states of BH which have valence character are calculated with a different and larger basis set than in the previous study, in order to obtain ab initio data of sufficient accuracy to treat the nonadiabatic interactions between the valence states and in particular the predissociation in A 1 Å. Secondly, the radial and the rotational-electronic coupling matrix elements calculated previously over the different *Corresponding author.…”

“…Ab initio multireference-single and double excitations configuration interaction (MRDCI) calculations [31] have been carried out on the eight lowest spin-singlet electronic states of BH and the dipole transition matrix elements as well as radial coupling and rotational electronic coupling matrix elements over these electronic states at 40 values of the B-H distance, varying from 1.2 to 20.0 bohr (as in [29]). In the present calculations, the AO basis set VQZ of Dunning [32] was employed as it was found previously [29] to be more appropriate for the valence states than the basis set employed for the Rydberg states of BH.…”

“…In a previous report by the present authors [29], multireference configuration interaction calculations on the electronic states of BH and BH þ were presented, with emphasis on the Rydberg states, the determination of quantum defect functions and vibrational autoionization of Rydberg states of BH. The ab initio results were in excellent agreement with the experimental transition energies of the Rydberg states, and in particular the theoretical value of the ionization potential was found to be in coincidence with the experimental value in Herzberg and Huber [30], however, the most recent experimental value of the ionization potential of BH [19] differs by 0.04 eV from the previous value [30].…”

“…The lower-lying electronic states of BH which have valence character are calculated with a different and larger basis set than in the previous study, in order to obtain ab initio data of sufficient accuracy to treat the nonadiabatic interactions between the valence states and in particular the predissociation in A 1 Å. Secondly, the radial and the rotational-electronic coupling matrix elements calculated previously over the different *Corresponding author. Email: ithe@eie.gr Rydberg states [29] are employed in order to calculate the formation of the 3p and 3d complexes in BH and BD. The formation of nl complexes in BH and BD has been reported by Bauer et al [7], and in particular the observation of the transition formally listed as H 1 Á-X 1 AE þ , which would be strictly forbidden for pure Ã, states has been attributed to the l-uncoupling in the 3d states [7].…”

Calculation of potential energy curves and quantum defects of the diatomic hydrides of first-row elements

“…2 and 3 for the PECS of BH and CH radicals which are already obtained in Refs. [4] and [5]. We hope to finish this project until the meeting.…”