A (II0+)-I-3-X-1 Sigma(+)(0+) and (BII1)-I-3-X-1 Sigma(+)(0+) transitions of GaI: an MRDCI study

A multireference singles and doubles configuration interaction (MRDCI) stud y based on relativistic effective core potentials has been carried out on G aI. The ground state of GaI is X(1)Sigma(+) with r(e) = 2.65 Angstrom and o mega(e) = 196 cm(-1). There is only one bound excited state ((3)Pi) below a n energy of 25 000 cm(-1). Potential energy curves of 12 low-lying Lambda-S states have been computed. The ground-state dissociation energy of Gal has been estimated to be 3.34 eV compared with the observed value of 3.47 eV. Spin-orbit coupling is included in the calculation. The splittings among th e four Omega components of the (3)Pi state are small. Transition probabilit ies of two observed transitions. A (3)Pi(0+)-X(1)Sigma(0+)(+) and B (3)Pi(1 )-X(1)Sigma(0+)(+) are calculated from CI energies and wavefunctions. The A -X transition has been found to be more probable than B-X. The radiative li fetimes of A and B states have been estimated. (C) 1999 Elsevier Science B. V. All rights reserved.