Ultrafast coupled electronic and protonic dynamics of H2O in intense laser fields by extended multi-configuration time-dependent Hartree-Fock method

Ultrafast coupled electronic and protonic dynamics of H 2 O exposed to a few-cycle intense near-infrared laser pulse is investigated by the extended multi-configuration time-dependent Hartree-Fock method beyond the Born-Oppenheimer approximation. We find that the excitation of the O H bond vibration can be induced by the laser pulse polarized perpendicular to the H-O-H plane. By analyzing the energy transfer between the electronic and protonic subsystems, we demonstrate that the energy absorbed by the electrons from the intense laser field is subsequently distributed to the motion of the protons via the electro-protonic interaction.