Electronic structure and potential energy surfaces of the ethylene radical cation at and in the vicinity of the 90°-twisted form

Abstract

The potential energy surfaces of the ethylene radical cation near the 90°-twisted form were clarified by an appropriate configuration interaction calculation. A characteristic conical intersection between the ground doublet and the first excited doublet states at a D2d 90°-twisted geometry was revealed. It was found that spin-charge separation occurs suddenly near the twist angle of 90°. The effect of substitution on the shape of the potential energy surfaces is also discussed.