An accurate three-dimensional potential energy surface for H3

TLDR

The study aimed to use the accurate H3 potential surface to evaluate ab initio and semiempirical methods for potential surface calculations, focusing on applications to other exchange reactions. The authors performed configuration interaction calculations with an extended one‑particle basis of 4 s‑type, 3 p‑type, and 1 d‑type Gaussian functions and a nearly complete n‑particle basis, adapting the direct CI method to the complete CI problem for three valence electrons. The resulting three‑dimensional potential energy surface for H3, computed for 156 nuclear configurations, achieves accuracy within 0.1 kcal mol⁻¹ of the exact clamped‑nuclei limit.

Abstract

An accurate three-dimensional potential energy surface for H3 has been obtained by the configuration interaction (CI) method. The calculated energies, for 156 nuclear configurations, with the energy of the saddle point taken to be zero, are believed to lie within 0.1 kcal/mole of the exact clamped-nuclei limit. The CI calculations used an extended one-particle basis set of 4 s-type, 3 p-type, and 1 d-type contracted Gaussian functions, and a nearly complete n-particle basis set. In order to solve the large secular problem, the direct CI method was adapted to the problem of complete CI for three valence electrons. The properties of the accurate H3 potential surface were used to evaluate ab initio and semiempirical methods for potential surface calculations, with emphasis on their applications to other exchange reactions.