Ab initio investigation of the vibronic structure of the C<inf>2</inf>H spectrum: Calculation of the hyperfine coupling constants for the three lowest-lying electronic states

Abstract

The hyperfine coupling constants (isotropic hfcc and four Cartesian components of the anisotropic tensor) are calculated for all three atoms of C2H in its three lowest-lying electronic states at various molecular geometries by means of the ab initio configuration interaction (MRD-CI) method. The off-diagonal electronic matrix elements involving the two species of the A′ symmetry are also computed. A diabatic transformation is performed leading to simple geometrical dependences of the hyperfine coupling constants. © 1991.