ÖAW DOC 24659: Concepts of solvation dynamics in molecular dynamics simulation
|awarded PhD||Esther Heid|
|funding period||08/2017 -|
|project sum||114 k €|
AbstractSolvation dynamics describes the rate of solvent reorganization after an electric perturbation, which can be realized through electronic excitation of a molecular fluorescent probe via a laser pulse. The resulting time-dependent fluorescence of the chromophore describes the transient behavior of solvent relaxation as the solvent molecules rearrange to the new charge distribution, stabilize the excited state and therefore lengthen the emitted fluorescence wavelength. This dynamic solvent response plays an important role in chemical reactions because it directly affects the reaction rates, as a retarded solvent response to the reaction passing the transition state may result in free energy barriers. Consequently, ``designing'' the solvation response may help to make reactions faster or more specific.
In this project, polarizable molecular dynamics simulations will help to interpret experimentally obtained data on solvation dynamics. In particular, the femtosecond dynamics which is not completely accessible by the current experimental setup as well as the decomposition of the contributing molecular processes will be provided, helping to understand the intriguing phenomenon of solvation dynamics. In addition to existing simulations, this study will improve the force field of the solute in several ways: The reparametrization of intramolecular potentials due to the excited state as well as introducing atomic polarizabilities for the excited state are essential for the improvement of the computational results in the initial femtosecond time regime and also allow for an analysis of the parallel ongoing vibrational relaxation.
Furthermore, this study will enhance the knowledge of the computational methodology in solvation dynamics by analysing the issues between non-equilibrium and equilibrium simulations since the latter rely on different aspects of the Linear Response Theory.