H^+- H₂ O collisions studied by time-dependent density-functional theory combined with the molecular dynamics method

H^+-H₂O collisions are investigated using the time-dependent density-functional theory combined with the molecular dynamics method, in which the electrons are described quantum mechanically within the framework of time-dependent density-functional theory and the ionic cores are described classically by Newton's equations. The feedback between quantum electrons and classical ions is self-consistently coupled by Ehrenfest's method. The electron capture, electron loss, and ionization cross sections are obtained in the energy range of 1-1000 keV and excellent agreements are achieved with available experimental and theoretical data. The orientation effects of the H2O target are found to be significant in the collision processes, especially in low-energy collisions.