Classical Dynamics of Harmonic Generation of the HydrogenMolecular Ion Interacting with Ultrashort Intense Laser Pulses

Abstract

Within Born-Oppenheimer approximation, by using the classical trajectorytheory, a description for the high-order harmonic generation of thehydrogen molecular ion interacting with ultrashort laser pulseshas been presented. The Coulomb singularities have been remedied by theregularization. The action-angle variables have been used to generatethe initial inversion symmetry microcanonical distribution.Within a proper intensity range, a harmonic plateau with only oddharmonics appears. For a larger intensity, because of the existence ofchaos, the harmonic spectra become noisier. For a large enough intensity,the ionization takes place and the harmonics disappear. Sothe chaos causes the noises, the ionization suppresses the harmonicgeneration, and the onset of the ionization follows the onset of chaos.