P8: First-principles surface photochemistry

Supervision:Thorsten Klüner, Thomas Frauenheim

Motivation and state of the art: Surface photochemistry occurs in many instances such as photocatalysis or solar energy conversion. Despite its ubiquitous nature, the atomistic understanding of underlying elementary processes remains a great challenge. In particular, the accurate calculation of electronically excited state potential energy surfaces (PES) of adsorbate-substrate systems constitutes an extremely difficult task.

Own work: Using embedded cluster calculations, we were able to calculate high-dimensional PES for ground and excited states for various adsorbate-substrate systems (CO, NO and H2O adsorbed on NiO, Cr2O3 and TiO2-surfaces). The dynamics of nuclear motion was simulated by stochastic wave packet calculation using a code developed in our group.

Aims and work plan: For the first time, we will investigate photodesorption of NO adsorbed on a rutile TiO2(110)-surface extending the method of local increments not only for calculations of the electronic ground state but also for excited states. We will use embedded cluster models to describe the geometric and electronic structure of the surface on CASSCF/CASPT-2 or CCSD(T) levels of theory, respectively. Multi-dimensional PES will be calculated which will be used as a prerequisite for stochastic quantum dynamical wave packet calculations to simulate the corresponding photochemical reactions. A methodological comparison will be performed with the DFT-TB approach applied in P9 and with density matrix-based schemes established in P7.