POTENTIAL-ENERGY SURFACES FOR THE LI- MRDCI STUDY OF THE GROUND-STATES AND LOWER EXCITED-STATES FOR DOUBLET LIFH(HF REACTION )

Ab initio electronic energy calculations are reported for 570 nuclear configurations of LiFH in C-s symmetry (three dimensional potential en ergy surface). The lower five doublet spin-state eigenfunctions (three (2)A' and two (2)A'') for UFH have been determined using a multiple r eference single and double excitations configuration-interaction (MRDC I) method and an extended triple-zeta-plus-polarization contracted Gau ssian basis set. As the Li atom approaches the HF diatomic, it first f orms a bent complex (106 degrees) with 28 kJ/mol of stabilization ener gy before reaching the transition state. The latter, also bent (73 deg rees) was located in the exit channel and is predicted to be 24 kJ/mol above the reactants. We argue that laser catalysis of the Li + HF --> LiF + H reaction would be possible and irradiation in the 6 000-9 000 cm(-1) range is predicted to enhance the reaction.