title: A new accurate and full dimensional potential energy surface of H5(+) based on a triatomics-in-molecules analytic functional form.
abstract: In this work a reliable full nine-dimensional potential energy surface for studying the dynamics of H(5)(+) is constructed, which is completely symmetric under any permutation of the nuclei. For this purpose, we develop a triatoms-in-molecules method as an extension of the more common diatoms-in-molecules one, which allows a very accurate description of the asymptotic regions by including correctly the charge-induced dipole and quadrupole interactions. Moreover, this treatment provides a semiquantitative description of all the topological features of the global potential compared with coupled cluster results. In particular, the hop of the proton between two H(2) fragments produces a double well in the potential. This resonant structure involving the five atoms produces a stabilization, lowering the barrier, and the triatoms-in-molecules yields to a barrier significantly higher than the ab initio results. Therefore, to improve the triatomics-in-molecules potential surface, two five-body terms are added, which are fitted to more than 110,000 coupled-cluster ab initio points. The global potential energy surface thus obtained in this work has an overall root mean square error of 0.079 kcal/mol for energies below 27 kcal/mol above the global well. The features of the potential are described and compared with previous available surfaces.
authors.affiliation: Departamento de Química Física, Facultad de Ciencias C-XIV, Unidad Asociada UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Aguado
authors.forename: P
authors.initials: P
authors.lastname: Barragán
authors.forename: R
authors.initials: R
authors.lastname: Prosmiti
authors.forename: G
authors.initials: G
authors.lastname: Delgado-Barrio
authors.forename: P
authors.initials: P
authors.lastname: Villarreal
authors.forename: O
authors.initials: O
authors.lastname: Roncero