CC-R12 calculations on the lowest stationary points of the H5+ energy surface

Abstract

The four stationary points lowest in energy on the H5+ potential energy surface are studied at various levels of sophistication including CCSD(T)-R12 calculations. Absolute energies are obtained with errors less than 0.5 kJ mol−1. Relative energies are supposed to be much more accurate. The binding energy (D0) of H5+ with respect to H3+ and H2 is 35.9±0.1 kJ mol−1. The D2d structure is a saddle point only ∽0.8 kJ mol−1 above two equivalent minima of C2v symmetry.