Theoretical investigations for electronic structures and photodissociation of bromine molecule

Abstract

We have theoretically studied the nonadiabatic transitions among the lower states with W = 1u symmetry {1u (Lindeman and Wiesenfeld, 1979) to 1u (Alexander et al., 2000)} in the photodissociation of Br2 using the complete active space self-consistent field (CASSCF) computations and the time-independent Schrodinger equations. The CASSCF wave function is formed from a complete distribution of a number of active electrons in a set of active orbitals, which in general constitute a subset of the total occupied space. From the configuration analysis of the CASSCF wave functions, we found that the nonadiabatic transition between 1u(Bracker et al., 1999) and 1u (Lindeman and Wiesenfeld, 1979) is a noncrossing type, while that between 1u (Bracker et al., 1999) and B3P0+u is a crossing type. The spectroscopic constants for the X1Sg+, A3P1u and B3P0+u states of Br2 have been calculated. The absorption cross-section for the ground and the lower excited states in the photodissociation of Br2 molecule has been presented as well as the numerical estimates of nonadiabatic transition probabilities. Also, the five highest occupied and the five lowest unoccupied orbitals of Br2 have been calculated. Key words: Nonadiabatic transitions, broimine molecule, photodissociation.