Ab initio study of the electric dipole transition moment for the C̃←X̃ electronic transition in acetylene: theoretical predictions of the absorption and magnetic circular dichroism intensities

Abstract

The electric dipole transition moment has been calculated a priori for the C̃ (1 1Π u)← X̃(1 1Π + g) electronic transition as a function of R(CC), using ab initio quantum chemical techniques including state averaged, complete active space MCSCF and multireference CI. The transition moment is then averaged over the vibrational wavefunctions for the CC stretch, and theoretical predictions are made for the adsorption oscillator strength and the magnetic circular dichroism (MCD) intensities, 〈Δϵ⦔ 1, for the lowest four vibrational bands originating from v=O in X̃.