A theoretical contribution to the characterization of the low-lying electronic states of BeBr including spin-orbit effects

Electronic states of BeBr correlating with the first two dissociation channels are investigated at a high level of electronic structure theory (CASSCF/MRCI) along with quintuple-zeta quality basis sets. Very reliable potential energy curves are constructed and regions of both avoided and curve crossings that greatly resemble the ones for BeCl are identified. For both the ground state (X (2)Sigma(+)) and the first excited one (A (2)Pi), this study corroborates the present still limited experimental knowledge about this system and significantly extends its spectroscopic characterization. For the three doublets in the interval between 30000 and 40000 cm(-1), the inclusion of spin-orbit effects neatly accounts for the interactions between the relativistic states. For the A - X band system, transition moments were evaluated and transition probabilities, as expressed by the Einstein emission coefficients, computed; radiative lifetimes completed the characterization of the A state. The C (2)Sigma(+) state was found to have two minima in the Lambda + S representation, the first one with just one vibrational level; this shallow potential then disappears when perturbations by the B (2)Pi and the a (4)Sigma(+) states are taken into account. (C) 2013 Elsevier Inc. All rights reserved.