Low-lying electronic states of HCN+ and the interpretation of the photoelectron spectrum of HCN

Abstract

The ground and the first excited states of the hydrogen cyanide cation have been calculated using the matrix Hartree–Fock approximation. The inclusion of the estimated correlation energy difference between these states yields a term value of the excited state in very good agreement with experiment. An account is given for the fact that HCN⁺ and N⁺₂ are isoelectronic but have their first two low-lying electronic states in reversed order.