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).