A theoretical study of spectroscopy and metastability of the CN dication

Potential energy curves of low-lying electronic states of the CN²⁺ dication and of the electronic ground states of CN⁺ and the neutral CN molecule were calculated using internally contracted multireference CI and the coupled cluster RCCSD(T) methods. Spectroscopic constants and adiabatic excitation energies of 13 quasibound electronic states of the dication were obtained and the energy of charge stripping of CN⁺ and double ionization energy of CN were predicted. Tunneling and spin-orbit induced predissociation lifetimes for the vibrational levels in the low-lying electronic states are presented and the metastability of the dication is discussed.