Molecular strong field ionization and high harmonic generation: A selection of computational illustrations

Abstract

Strong field ionization (SFI) and high harmonic generation (HHG) are the central processes that enable attosecond physics. To date, most theoretical investigations of SFI and HHG rely on semiclassical methods, most notably the strong field approximation (SFA), which treats the continuum states of the liberated electron as plane waves. SFA is a very successful conceptual model for atoms and small molecules, and leads to an intuitively satisfying picture of HHG (i.e. the three-step model). However, as SFI and HHG experiments enter the regime of polyatomic molecules, many approximations made in SFA-type models can no longer be ignored even for a qualitatively correct understanding. In this contribution, we present a selection of results from our efforts toward ab initio modeling of strong field processes in molecular systems. The method is applicable to single-electron ionization and HHG of gas-phase polyatomic molecular targets.