Quantitative rescattering theory for high-order harmonic generation from aligned molecules*

By employing the recently proposed Quantitative Rescattering Theory (QRS) combined with accurate photoionization transition dipoles for aligned molecules, we show that most of the existing experimental results for high-order harmonic generation (HHG) from CO$_{2, }$N$_{2}$, and O$_{2}$ can be nicely reproduced. In our calculations, the returning electron wavepackets are obtained from the strong-field approximation or from solution of the time-dependent Schrodinger equation for a reference atom, whereas the transition dipoles are obtained from state-of-the-art molecular photoionization calculations. Our results show that quantitative description of the HHG from aligned molecules has become possible.