Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 22: Poster: Interaction with strong or short laser pulses

A 22.13: Poster

Dienstag, 19. März 2013, 16:00–18:30, Empore Lichthof

Solving the Kohn-Sham equations for matter in high-intensity laser fields — •Volker Mosert and Dieter Bauer — Institut für Physik, Universität Rostock, 18051 Rostock

Solving for the many-body wave function of the interacting electrons via the time-dependent Schrödinger equation is prohibitive. Instead, in time-dependent density functional theory the problem is transformed to a set of one-particle, nonlinear Schrödinger-like equations, the time-dependent Kohn-Sham (KS) scheme. However, solving one-particle Schrödinger equations for strong-field interactions is still very demanding because large simulation volumes due to the extensive electron excursions are required. Pseudo potentials are commonly used in order to avoid dealing explicitly with inner electrons and the need to resolve the small spatial scale set by them. However, we found that a proper description of the inner electrons is essential to obtain, e.g., the correct ionization rate. Moreover, inner electrons are directly involved in the dynamics if the interaction with short-wavelength (e.g., FEL) radiation is to be simulated. We implement a method which can handle the large simulation volumes necessary for strong-field simulations without resorting to pseudo potentials. For this purpose we use an adaptive resolution strategy to handle the Coulomb potentials close to the ionic centers via a coordinate transformation in our finite difference approximation of the KS-Hamiltonian. An important goal of our work is high scalability with respect to the number of grid points. We show that the application of multi-grid techniques to the discretized KS equations leads to very good scaling properties.