title: Three-step model for high-harmonic generation in many-electron systems.
abstract: The three-step model (TSM) of high-harmonic generation (HHG) is generalized to atomic and molecular many-electron systems. Using many-body perturbation theory, corrections to the standard TSM due to exchange and electron-electron correlations are derived. It is shown that canonical Hartree-Fock orbitals represent the most appropriate set of one-electron states for calculating the HHG spectrum. To zeroth order in many-body perturbation theory, a HHG experiment allows direct access, in general, to a combination of occupied Hartree-Fock orbitals rather than to the highest occupied molecular orbital by itself.
authors.affiliation: Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Robin
authors.initials: R
authors.lastname: Santra
authors.forename: Ariel
authors.initials: A
authors.lastname: Gordon