Cross sections for vibrational excitation of H2O by electron impact: benchmark system and manual for Quantemol-EC

Cross sections and thermally averaged rate coefficients for vibration (de-)excitation of a water molecule by electron impact are computed. One and two quanta excitations are considered for all three normal modes. The calculations use a theoretical approach that combines the normal mode approximation for vibrational states of water, a vibrational frame transformation employed to evaluate the scattering matrix for vibrational transitions and the UK molecular R-matrix code for electron-scattering calculations. The interval of applicability of the rate coefficients is from 10 to 10,000K. The developed methodology for computing non-resonant vibrational excitation cross-sections employed here has recently been incorporated, with some simplifications, into the QEC (Quantemol Electron Collisions) expert system used to run the new (UKRmol+) UK Molecule R-matrix code. Comparison of results obtained using the complete and QEC approaches are discussed. Recommendations for QEC users are developed.