Classical dynamics of strong-field ionization

We have used classical dynamics to study high-field-intensity ionization of atoms for various parameters and different potentials. The numerical calculations establish evidence that the ionization probability P vanishes in the limit of large field amplitude and small Kramer’s parameter A/${\mathrm{\omega }}^2$, where A is the field amplitude and ω is the frequency. We also show that the reported suppression of P for large values of A at fixed frequency ω in quantum dynamics is consistent with results from the corresponding classical ensemble, depending upon the potential, and within the context of comparison. These results, combined with other data, indicate that the classical-ensemble initial conditions, together with the modulation of the potential by the externally applied field, play a significant role in the classical picture of photoionization.