Research

The main topic of our research is modeling of electronically excited states, i.e. computational photophysics and photochemistry. Photochemical phenomena play a key role in many natural and industrial processes. When we excite a molecule into another electronic state, we bring a considerable amount of energy into the system, increasing the molecule’s reactivity and possibly triggering further processes. Intuition gained studying molecules in the ground electronic state cannot help us predict properties in the excited state, and different chemical behavior can be expected in every electronic state we reach. This is one of the reasons why computational treatment is necessary, providing a cheaper alternative to demanding experiments.

Compared to ground-state calculations, modeling of electronically excited states is more challenging, and a smaller number of reliable methods is available to treat, e.g., state switching. Ab initio photochemical calculations have been considerably improving during the last years, with respect to methodology, size of studied systems, calculation speed-up and potential energy surfaces (PES) interpolation. However, simulating photochemical processes on the molecular level is usually limited to picoseconds. Long-term processes (≈ > 10 ps) are often not accounted for or decoupled from short-term ones. Still, many important processes, like photodissociation over a barrier, intersystem crossing, fluorescence/phosphorescence, absorption of a second photon, or reactions with other molecules, take place on a longer timescale and might be as important as the short-time behavior. Our interest is to model the processes on the larger timescale, possibly using quantum chemical calculations on GPUs.

We are interested in various aspects of photochemical processes, including modeling of absorption and photoionization spectra, photodynamics, and influence of hydration, helium solvation and ionic environment on photochemical  processes. We model action spectra by accounting for explicit interaction of the laser pulse with an ion, including multiphoton excitation and fluorescence.