Ab initio potential and rotational spectra of the CO-N-2 complex

Ab initio calculations of the intermolecular potential energy surface (PES) of CO–N2 have been carried out using the closed-shell single- and double-excitation coupled cluster approach with a non-iterative perturbative treatment of triple excitations method and the augmented correlation-consistent quadruple-zeta (aug-cc-pVQZ) basis set supplemented with midbond functions. The global minimum (De = 117.35 cm−1) of the four-dimensional PES corresponds to an approximately T-shaped structure with the N2 subunit forming the leg and CO the top. The bound rovibrational levels of the CO–N2 complex were calculated for total angular momenta J = 0–8 on this intermolecular potential surface. The calculated dissociation energies D0 are 75.60 and 76.79 cm−1 for the ortho-N2 (A-symmetry) and para-N2 (B-symmetry) nuclear spin modifications of CO–N2, respectively. Guided by these bound state calculations, a new millimeter-wave survey for the CO–N2 complex in the frequency range of 110-145 GHz was performed using the intrac...