Tunnelling lifetimes of the rovibronic levels in the B electronic state of the CH radical obtained fromab initiodata

Rovibronic spectroscopic parameters have been obtained for the X and B states of the CH radical using accurate ab initio potentials. The potentials have been calculated with the multi-reference averaged quadratic coupled cluster (MR-AQCC) method using a large reference space and the cc-pVQZ basis. The one-dimensional Schrödinger equation of the nuclei has been solved exactly to get the vibrational—rotational energy levels. The energies and tunnelling predissociation widths of quasibound levels on these potentials have been calculated, plus the Franck—Condon factors for many of the rovibronic transitions.