Theoretical Methods for Attosecond Coupled Electron-nuclear Dynamics In Molecular Photoionization

Abstract

This chapter focuses on theoretical methods that have been especially designed to describe time–resolved coupled electron-nuclear dynamics resulting from the interaction of molecules with XUV attosecond pulses. These pulses inevitably lead to ionization of the molecule, so that any meaningful theoretical description of the ensuing dynamics must be based in the solution of the time–dependent Schrödinger equation by explicitly including (i) electronic and nuclear degrees of freedom, and (ii) a description of the electronic continuum of the system. The chapter starts with a description of full dimensional ab initio methodologies, which are only feasible for diatomic molecules, but provide a benchmark for applications in more complex targets. Then the performance of these methods is illustrated for three different systems in a variety of physical scenarios: two–photon resonant ionization and high-harmonic generation in H2+, laser–induced Rabi flopping in multi–photon ionization of H2, and dissociative ionization of N2 within an attosecond XUV–pump/IR–probe scheme. For large molecules, the description of the ionization process requires more approximate methods and nuclear dynamics can only be incorporated by adopting classical or semi–classical approaches. The chapter concludes with a brief description of the latter methods and their performance in investigating the coupled electron and nuclear dynamics induced by attosecond pulses in the amino acid glycine.