Theoretical investigations for electronic structures and photodissociation of bromine molecule

We have theoretically studied the nonadiabatic transitions among the lower states with Omega = 1(u) symmetry {1(u) (Lindeman and Wiesenfeld, 1979) to 1(u) (Alexander et al., 2000)} in the photodissociation of Br(2) 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 1(u) (Bracker et al., 1999) and 1(u) (Lindeman and Wiesenfeld, 1979) is a noncrossing type, while that between 1(u) (Bracker et al., 1999) and B(3)Pi(0+u) is a crossing type. The spectroscopic constants for the X(1)Sigma(+)(g), A(3)Pi(1u) and B(3)Pi(0+u) states of Br(2) have been calculated. The absorption cross-section for the ground and the lower excited states in the photodissociation of Br(2) 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 Br(2) have been calculated.