Molecular Schrödinger Equation. X. Potential Surfaces for Ground and Excited States of Isosceles H3++ and H3+

Abstract

Accurate potential‐energy surfaces are reported for the ground states, and for several excited states, of the isosceles triangular configurations of the molecular ions H₃²⁺ and H₃⁺. The ground states are ${}^2{A}_1$ and ${}^1{A}_1$ , respectively, of group $C_{\text{2υ}}$ , and these include the ${\Sigma }_g$ linear symmetric forms and the $A_1\prime$ states of the equilateral $D_{\text{3h}}$ triangles. The four excited‐state surfaces are ${}^2{B}_1$ and ${}^2{B}_2$ for H₃²⁺, as well as ${}^1{B}_1$ and ${}^1{B}_2$ for H₃⁺; these include the ${\Pi }_u$ and ${\Sigma }_u$ states of the linear $D_{\mathrm{\infty h}}$ ions and the $A_2″$ and $\mathrm{E\prime }$ states of the $D_{\text{3h}}$ ions. These excited states are of possible interest in connection with ultraviolet spectroscopic studies of H₃⁺, long known from mass spectrometry to be a stable species. Each of the six surfaces is given in analytic form, and as an energy contour map. The two‐electron wavefunctions used are basically of the configuration type, with an extensive additional treatment of electron correlation. In all cases the required matrices were computed with the new Diophantine integration scheme, which supercedes the now obsolete Monte Carlo method employed in our earlier papers on H₃⁺.