Inelastic Triatom-Atom\nQuantum Close-Coupling Dynamics\nin Full Dimensionality: All Rovibrational Mode Quenching of Water\nDue to the H Impact on a Six-Dimensional Potential Energy Surface

The rovibrational level populations, and subsequent emission\nin\nvarious astrophysical environments, are driven by inelastic collision\nprocesses. The available rovibrational rate coefficients for water\nhave been calculated using a number of approximations. We present\na numerically exact calculation for the rovibrational quenching for\nall water vibrational modes due to collisions with atomic hydrogen.\nThe scattering theory implements a quantum close-coupling (CC) method\non a high level ab initio six-dimensional (6D) potential energy surface\n(PES). Total rovibrational quenching cross sections for excited bending\nlevels were compared with earlier results on a 4D PES with the rigid-bender\nclose-coupling (RBCC) approximation. General agreement between 6D-CC\nand 4D-RBCC calculations are found, but differences are evident including\nthe energy and amplitude of low-energy orbiting resonances. Quenching\ncross sections from the symmetric and asymmetric stretch modes are\nprovided for the first time. The current 6D-CC calculation provides\naccurate inelastic data needed for astrophysical modeling.