P9: Excited state molecular dynamics using TDDFTB in frequency and time domain

Supervision: Thomas Frauenheim, Thorsten Klüner, Angel Rubio

Motivation and state of the art: The understanding and control of energy and charge transfer and excited electron hole separation at hybrid molecule oxide interfaces is of central importance for sustainable solutions in efficient pollutant degradation and energy conversion processes. While highest accuracy methods are limited to model-like situations, more efficient DFTB approaches steadily improve in accuracy.

Own work: Based on time-dependent (TD) DFT we have developed an efficient TD-DFT tight-binding (TB) approach (http://www.dftb.org/) which for singlet and triplet (S/T) excited state energies of organic molecules (chromophores) performs similarly accurate as highest level hybrid DFT-methods. Applications to photo-induced charge transfer states in visible light activation of nitric oxide (NO) degradation are in good agreement with experimental results.

Aims and work plan: The DFT-TB and TD-DFT-TB methods will be advanced by adapting recent corrections in order to study the reaction molecular dynamics (MD) of pollutant molecules and chromophores on pristine ideal and stepped hydrogenated, hydroxylated metal oxide (MO)-surfaces in the ground and in excited states without and in the presence of solvents. Multi-dimensional potential energy surfaces of model-type configurations will be calculated and validated with respect to CCSD(T) level of theory. After determining the correct molecule-oxide vertical excitation energies for most stable configurations, MD simulations will be explored in ground and excited states to quantify reaction pathways and discriminate the possible gating effects by varying environmental conditions. Collaborations with P5, P6, P8 and P10 will help to derive a fully quantitative picture of charge dynamics at hybrid interfaces.