UV irradiation of cellular DNA leads to the formation of mutagenic pyrimidine derived dimer lesions. One of the stable end products of the lesion forming pathways are DNA Dewar lesions. Here we report that the TpC derived Dewar lesions are efficiently repaired by the repair enzyme (6-4) photolyase, while the TpT derived Dewar lesion is unrepairable. We provide ... READ MORE

The knowledge of conical intersection seams is important to predict and explain the outcome of ultrafast reactions in photochemistry and photobiology. They define the energetic low-lying reachable regions that allow for the ultrafast non-radiative transitions. In complex molecules it is not straightforward to locate them. We present a systematic approach to predict ... READ MORE

Optimal control theory and optimal control experiments are state-of-the-art tools to control quantum systems. Both methods have been demonstrated successfully for numerous applications in molecular physics, chemistry and biology. Modulated light pulses could be realized, driving these various control processes. Next to the control efficiency, a key issue is the ... READ MORE

A combination of experimental and theoretical techniques is used to study the photoinduced ring-opening/closure of a trifluoromethyl-indolylfulgide. Time-resolved UV/vis pump and IR probe measurements are performed in the subpicosecond to 50 ps time range. A combination of experimental and theoretical techniques is used to study the photoinduced ... READ MORE

Non-adiabatic on-the-fly molecular dynamics (NA-O-MD) simulations require the electronic wavefunction, energy gradients, and derivative coupling vectors in every timestep. Thus, they are commonly restricted to the excited state dynamics of molecules with up to ≈20 atoms. We discuss an approximation that combines the ONIOM(QM:QM) method with NA-O-MD simulations to ... READ MORE

The photophysical and photochemical processes driving the formation of the ultraviolet (UV)-induced DNA Dewar lesion from the T(6-4)T dimer are investigated by time-resolved spectroscopy and quantum chemical modelling. Time-resolved absorption and emission spectroscopy in the UV revealed a biexponential decay of the electronically excited state (S1) with time ... READ MORE

We combine broad-band femtosecond transient absorption measurements and on-the-fly molecular dynamics calculations to decipher the microscopic evolution of the geometry and solvation of photogenerated benzhydryl cations in bulk solution. The identification of the transition state or a short-lived intermediate of a chemical reaction is essential for the ... READ MORE

Based on p’th order Cartesian Taylor expansions of Coulomb interactions and on hierarchical decompositions of macromolecular simulation systems into hierarchies of nested, structure-adapted, and adaptively formed clusters of increasing size, fast multipole methods are constructed for rapid and accurate calculations of electrostatic interactions. These so-called ... READ MORE

We have carried out “first-principles” Born–Oppenheimer molecular dynamics (BOMD) simulations of the phosphate ions H2PO4– and HPO42– in liquid water and have calculated their IR spectra by Fourier transform techniques from the trajectories. IR bands were assigned by a so-called “generalized normal coordinate analysis”. The effects of including ... READ MORE