Spectroscopic parameter and molecular constant investigations on X2Σ+ and A2Πi states of 12C14N, 12C15N, 13C14N and 13C15N species

The potential energy curves of X2Σ+ and A2Πi states of CN radical have been investigated using the complete active space self-consistent-field method followed by the highly accurate valence internally contracted multireference configuration interaction approach in combination with the cc-pV5Z basis set. With the second-order Douglas-Kroll Hamiltonian approximation, the effect on the PECs by the relativistic corrections has been taken into considerations. Employing the cc-pcV5Z basis set, the effect on the spectroscopic parameters by the core-correlate corrections has been evaluated. For the X2Σ+ and A2Πi electronic states, the spectroscopic parameters of these four species (12C14N, 13C14N, 12C15N and 13C15N) have been studied. With the CN potential energy curves obtained here, 43 vibrational states for the X2Σ+ and 60 for the A2Πi states are predicted when the rotational quantum number J is equal to zero (J = 0). The vibrational manifolds are determined for the first 40 vibrational states when J = 0. And the rovibrational energy levels of four species are calculated until J = 29. The results of spectroscopic parameters and molecular constants have been compared in detail with those of the investigations reported in the literature.