Theoretical studies of the HeCN+ and NeCN+ molecular ions

Self-consistent field calculations are presented for HeCN⁺ using several basis sets; calculations for HeH⁺ with the same basis sets are given for comparison. These predict that HeCN⁺ is stable with a He-CN⁺ dissociation energy between 1.5 and 2.0 eV. The binding is found to be mainly electrostatic in nature. Rotation and hyperfine spectral constants are predicted. Similar calculations indicate that the isocyanide HeNC⁺ is not stable. Preliminary calculations on NeCN⁺ indicate that it is as stable as HeCN⁺. The possibility of observing noble gas molecular ions in laboratory experiments and in interstellar space is discussed.