THE LOW-LYING ELECTRONIC STATES OF LIB

The spectroscopic constants for the triplet and singlet states of LiB below about 30000 cm(-1) are determined using an internally contracted multireference configuration-interaction approach. The ground state i s (3) Pi as found in previous work. Transitions between the (3) Pi sta te and the (1)(3) Sigma(-), (2)(3) Pi, and (3)(3) Pi states are studie d in detail. The (1)(3) Sigma(-) state is low-lying and may be hard to observe in many experimental approaches. The (2)(3) Pi and (3)(3) Pi states have bond lengths that are significantly longer than the ground state, resulting in transition intensities that are spread out over m any vibrational levels of the ground state.