Accurate double many-body expansion potential energy surface for triplet H3+. I. The lowest adiabatic sheet (a3Σu+)

Abstract

We report on a global potential energy hypersurface for the lowest triplet state of H3+ based on the double many-body expansion (DMBE) method and ab initio data points of V5Z quality. These data points are represented with a root mean square deviation of only 3.46 cm−1 in the energy region below the H2+(X2Σg+)+H(2S) dissociation threshold and with less than 15 cm−1 up to the three-particle breakup energy. As expected from a DMBE approach, all dissociation limits are represented accurately and are approached in a physically correct manner.