Jörg Liebers

• The theoretical framework of wave packet dynamics can be applied to describe many aspects in molecular physics and the interaction of matter and light. In this thesis wave packet dynamics occurring in various molecular systems have been investigated. This includes the simulations of nuclear wave packet dynamics in different electronic states of diatomic molecules initiated by femtosecond laser pulses. With these simulations the theoretical analyses of femtosecond time-resolved four-wave mixing experiments was possible. Furthermore a theoretical description of non-resonant multi-photon excitations has been given, which allows to study the wave packet dynamics initiated by such processes in the time domain. This is essential for the application of non-resonant femtosecond laser pulse excitations to control and investigate molecular dynamics. A further focus of this thesis is the investigation of excitation energy transfer in biological pigment complexes. A hybrid quantum classical approach is applied to describe excitonic wave packet dynamics in such complex molecular aggregates. This approach was verified within an artificial test system an then applied to the light harvesting system II of a purple bacteria. To perform simulations on this system, data from all-atom classical molecular dynamics simulations have been used to construct a model system for this complex. This allowed for the investigation of the excitation energy transfer dynamics which are an important aspect of the light harvesting process in photosynthesis. For these systems it was shown that the wave packet approach in combination with classical molecular dynamics simulations is a powerful tool to describe quantum dynamical processes in large molecular systems.