Giant Renner–Teller vibronic coupling in the BF2 radical: An ab initio study of the X 2A1 and A 2Π electronic states.

The potential energy surfaces (PESs) of the ground X 2A1 and the first excited A 2Π (1 2B1,2 2A1) electronic states of the BF2 radical have been studied ab initio, using a large basis set and CCSD(T) and EOM-CCSD techniques. The calculated PESs were used to variationally calculate the energy levels up to ≈36 000 cm-1 above the ground state. The Renner–Teller splitting parameter ([variant_greek_epsilon]=0.928) found for the A 2Π state of this radical is very large which results in an unusual excited state energy level structure. [ABSTRACT FROM AUTHOR]