UNDERSTANDING CHEMICAL REACTIONS INVOLVING NON-ADIABATIC TRANSITIONS: PREDISSOCIATION OF THE ELECTRONICALLY EXCITED Li-HF COMPLEX

The electronic predissociation from several excited electronic states of LiHF is studied using a time dependent Golden rule treatment, in an adiabatic representation. The potential energy surfaces used are those developed recently [J. Chem. Phys. 119 (2003) 10088] to simulate the experimental spectrum. The nonadiabatic couplings are calculated using highly correlated electronic functions and a finite difference method. It is found that the electronic predissociation process towards the ground electronic state yields to the formation of LiF products, with a large probability, > 90%. Also, the lifetimes associated to the A states are much shorter than for the B state. It is inferred that the electronic predissociation from the B and B’ electronic states should take place through the A electronic state, which acts as a doorway. Such process is explained by important ∑ – Π vibronic couplings appearing between the A, B and B’s.