Six-dimensional ab initio potential energy surface and bound States for He-H2S complex

We present a new six-dimensional potential energy surface for He-H2S including the intramolecular Q1, Q2, and Q3 normal modes for the ν1 symmetric stretching, ν2 bending and ν3 asymmetric stretching of H2S. The potential was calculated at the coupled-cluster singles and doubles with noniterative inclusion of connected triples [CCSD(T)]-F12a level with augmented correlation-consistent polarized-valence triple-zeta (aug-cc-pVTZ) basis set plus the midpoint bond function (3s3p2d1f1g). Three vibrationally averaged potentials with H2S at the vibrational ground state ν1 as well as the excited states ν2 and ν3 were generated from the integration of the six-dimensional potential over the Q1, Q2 and Q3 coordinates. Each potential has a planar T-shaped global minimum, a planar local minimum, two inplane saddle points as well as an out-plane saddle point. The global minimum is located at R=3.46 A, θ=109.9° and φ=0.0° with a well depth of 35.301 cm−1. The radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm were employed to calculate the rovibrational energy levels. The calculated band origins are blue-shifted (0.025 cm−1 and 0.031 cm−1) and (0.041 cm−1 and 0.060 cm−1) for He-(para-H2S) and He-(ortho-H2S) in the ν2 and ν3 region of the H2S molecule, respectively.