Many-electron effects of strong-field ionization described in an exact one-electron theory

If we are interested in one-electron observables of a many-electron system, a many-electron dynamics can be represented exactly by a one-electron dynamics with effective potentials. This dimensionality reduction is achieved by the formalism of the Exact Electron Factorization (EEF). The study of the time-dependent features of the EEF potentials for a model of an atom ionized by an ultrastrong and ultrashort laser pulse sheds light upon how to construct computationally feasible approximations. The simplest approximation — the time-independent conditional amplitude (TICA) approximation — reproduces the exact dynamics for high laser field frequencies and is therefore a complementary method to single-active electron (SAE) approaches. For low frequencies there is excited state dynamics in the core region of the atom leading to a time-dependent ionization barrier in the EEF potential. Provided the core dynamics can be modeled successfully, a multi-state extention of the TICA approximation can correctly describe many-electron effects.

References:
J. Kocák, A. Schild, Phys. Rev. Research, to be published.