You are here: Home Events Seminar Series 2016 … 19.04.2016 - Oliver Stauffert …

19.04.2016 - Oliver Stauffert - Repulsive Van der Waals forces and density functional theory

When Apr 19, 2016
from 06:00 PM to 07:00 PM
Where R023, Rechenzentrum, Hermann-Herder-Str. 10
Add event to calendar vCal
iCal











Van der Waals forces describe fundamental interactions between neutral molecules and atoms. The primary characteristics of the Van der Waals forces are given by the London formula UVdW ~ C6 / R⁶. The C6 coefficient can be obtained from the excitations of the molecules and their transition energies. For ground state molecules, the Van der Waals interaction is generally attractive. Negative transition energies in excited molecules, can lead to repulsive Van der Waals forces. In order to understand this phenomenon, molecules and their Van der Waals interactions are analyzed with density functional theory (DFT) and time dependent density functional theory (TD-DFT), where it is possible to obtain absorption spectra, transition energies and probabilities. Currently we are in collaboration with the Stienkemeier group to investigate the possibilities to detect singlet fission events. In singlet fission, singlet excitations can decay into into two triplet excitations, which are long living due to their low recombination rates. Furthermore these states might be preferential to lead to charge transfer processes or photo voltaic devices. We use TD-DFT to analyze the possibilities to detect a triplet population, representing the signature for the occurrence of singlet fission events.