Quantum dynamics of energy transfer for H collisions with water

Modeling of molecular emission spectra from the interstellar medium requires the calculation of rate coefficients for excitation by collisions with abundant species. Water is an abundant molecule in a variety of astrophysical environments, and has been the focus of countless theoretical astrophysical studies and observations. In this work we report a full-dimensional (6D) potential energy surface (PES) and scattering calculations for the H$_2$O-H collision system. The 6D PES was calculated using the high-level ab initio RCCSD(T)-F12b method. A two-component invariant polynomial method was applied to fit the PES analytically in 6D. The pure rotational state-to-state cross sections and rate coefficients from selected initial states of H$_2$O were compared with previous theoretical results. We also consider the calculation of rovibrational state-to-state cross sections and rate coefficients of H$_2$O in collision with H for the fundamental vibrational modes of water, $\nu_1$ (symmetric stretching), $\nu_2$ (bending mode), and $\nu_3$ (antisymmetric stretching).