Method of Diatomics-in-Molecules. VII. Excited Singlet States of H3+

Diatomics-in-molecules theory is applied to the excited singlet-state functions of H3+ which are anti-symmetric to the molecular plane. If one uses only 1s and 2p AO's, it is possible to construct six covalent singlet valence-bond wavefunctions of this type, and this set reduces to A21″ + 1 A1″ + 21 E″ for equilateral triangles, 31 A2 + 31 B1 for isosceles triangles, or one component of each of 3 1Πg + 3 1Πu for linear symmetrical H3+. Potential-energy surfaces for all states have been computed. None of the states appear to be stable or metastable. For the lowest energy A21″ state for equilateral H3+, the diatomics-in-molecules results agree with a previous extensive ab initio calculation by Conroy within 7 kcal.