Attosecond pumping of nonstationary electronic states of LiH: Charge shake-up and electron density distortion

Electronic reorganization during and after excitation by an intense ultrashort pulse is computed for LiH in a many-electron multireference time-dependent approach at a fixed nuclear geometry. The electronic dipole moment is used to probe the temporal response of the charge density. Above a field-strength threshold, there is an extensive Stark shifting and Rabi broadening of levels with corresponding distortion of the charge distribution whose response at strong fields is neither adiabatic nor diabatic. A nonresonant IR pulse is more effective in inducing charge shake-up during the pulse.