Trihydrogen Cation Helium Clusters: A New Potential Energy Surface

Abstract

AbstractWe present a new analytical potential energy surface (PES) for the interaction between the trihydrogen cation and a He atom, , in its electronic ground state. The proposed PES has been built as a sum of two contributions: a polarization energy term due to the electric field generated by the molecular cation at the position of the polarizable He atom, and an exchange‐repulsion and dispersion interactions represented by a sum of “atom‐bond” potentials between the three bonds of and the He atom. All parameters of this new PES have been chosen and fitted from data obtained from high‐level ab‐initio calculations. Using this new PES plus the Aziz‐Slaman potential for the interaction between Helium atoms and assuming pair‐wise interactions, we carry out classical Basin‐Hopping (BH) global optimization, semiclassical BH with Zero Point Energy corrections, and quantum Diffusion Monte Carlo simulations. We have found the minimum energy configurations of small He clusters doped with , , with N=1–16. The study of the energies of these clusters allows us to find a pronounced anomaly for N=12, in perfect agreement with previous experimental findings, which we relate to a greater relative stability of this aggregate.