The structure of CCH+

Abstract
Molecular orbital theory is used to examine relative energies of low‐lying electronic states of the ethynyl cation CCH+. A triplet 3ru is found to be the ground state at the highest level of theory with another triplet 3J only 2.4 kcal/mole higher in energy. The closed‐shell 1J+ state lies 59 kcal/mole above the ground state.