DESY is one of the world's leading accelerator centers and a member of the Helmholtz Association. DESY develops, builds, and operates large particle accelerators used to investigate the structure of matter. The Center for Free-Electron Laser Science (CFEL), which is located on the DESY campus in Hamburg, is a joint enterprise of DESY, the Max Planck Society (MPG), and the University of Hamburg. CFEL is designed to advance science with next-generation light sources.

Our group, the CFEL Theory Division (http://desy.cfel.de/cfel_theory_division/), develops theoretical and computational tools to predict the behavior of matter exposed to intense electromagnetic radiation. We employ quantum-mechanical and classical techniques to study ultrafast processes that take place on time scales ranging from picoseconds to attoseconds. 

We participate in a new research cluster of excellence called the Hamburg Centre for Ultrafast Imaging (CUI). CUI at the University of Hamburg is being funded through the Excellence Initiative of the German Research Foundation (DFG). For more information on CUI, please visit http://www.cui.uni-hamburg.de/en/ 

Within the framework of CUI, we invite applications for the following two Ph.D. positions. Please send your application by e-mail to the respective project leader. Please do not forget to quote the position ID.

1) Theory of nuclear and electronic dynamics in molecules after deep-shell ionization

The ultrafast dynamics of molecular systems after inner-shell ionization by extreme ultraviolet or x-ray radiation is currently far from being well understood. The interaction with ionizing radiation brings the system to a manifold of highly excited and non-stationary electronic states, from which possibly further electrons can be emitted, and on which complex nuclear dynamics and often fragmentation take place. Such combined processes constitute what could be defined as molecular damage, and are unavoidable in e.g. imaging applications with high energy photons. A main goal of the research project will be to obtain a deeper theoretical understanding of the ultrafast time evolution of highly excited molecular systems in which both electronic and nuclear dynamics play a role. To this end, the PhD candidate will be involved in the development of tools of quantum-classical nature, in which the electronic dynamics is treated by quantum mechanics, whereas the motion of the nuclei is described by classical trajectories. One of the main challenges will be to formulate and implement an adequate description of the highly excited molecular electronic states. The project will provide a strong training in the areas of electronic structure, molecular dynamics and non-adiabatic effects, and code development.

Position ID: CUI-A.1.1-Vendrell
Project Leader: Dr. Oriol Vendrell-Romagosa
E-mail: oriol.vendrell(at)cfel.de

2) Quantum-mechanical simulations of ultrafast reactions in liquids

The central goal of this project is to take critical steps towards the real-time study of chemical dynamics in the presence of a bath. This bath could be, for example, a solvent such as water in a chemical reaction or a solid surface in heterogeneous catalysis. Because of the complexity of the problem, it is generally not well understood how the bath influences the reaction chemistry. A related problem is the fact that for time-resolved studies of the detailed atomic motions during a chemical reaction, a large fraction of all molecular reactants in the sample must be forced to start undergoing the chemical reaction at the same time. This requirement to provide a trigger that is faster than the dynamical time scale of interest is the reason why femtochemistry nowadays is largely restricted to photochemical reactions that are associated with electronically excited states of the reacting species. The fundamental problem of triggering and clocking thermal chemical reactions remains unsolved. In this context, we would like to give a Ph.D. student the opportunity to develop strategies for combining quantum-wavepacket propagation methods for molecular dynamics with path-integral techniques for open systems. The goal is the simulation of chemical dynamics in liquids driven by electromagnetic fields.

Position ID: CUI-A.2.1-Santra
Project Leader: Prof. Robin Santra
E-mail: robin.santra(at)cfel.de

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