TY  - INPR
A1  - Lindner, Joachim O.
A1  - Sultangaleeva, Karina
A1  - Röhr, Merle I. S.
A1  - Mitric, Roland
T1  - metaFALCON: A program package for automatic sampling of conical intersection seams using multistate metadynamics
T2  - Journal of Chemical Theory and Computation
N2  - The multistate metadynamics for automatic exploration of conical intersection seams and systematic location of minimum energy crossing points in molecular systems and its implementation into the software package metaFALCON is presented. Based on a locally modified energy gap between two Born–Oppenheimer electronic states as a collective variable, multistate metadynamics trajectories are driven toward an intersection point starting from an arbitrary ground state geometry and are subsequently forced to explore the conical intersection seam landscape. For this purpose, an additional collective variable capable of distinguishing structures within the seam needs to be defined and an additional bias is introduced into the off-diagonal elements of an extended (multistate) electronic Hamiltonian. We demonstrate the performance of the algorithm on the examples of the 1,3-butadiene, benzene, and 9H-adenine molecules, where multiple minimum energy crossing points could be systematically located using the Wiener number or Cremer–Pople parameters as collective variables. Finally, with the example of 9H-adenine, we show that the multistate metadynamics potential can be used to obtain a global picture of a conical intersection seam. Our method can be straightforwardly connected with any ab initio or semiempirical electronic structure theory that provides energies and gradients of the respective electronic states and can serve for systematic elucidation of the role of conical intersections in the photophysics and photochemistry of complex molecular systems, thus complementing nonadiabatic dynamics simulations.
KW  - Computational Chemistry
KW  - Metadynamics
KW  - Hydrogen
KW  - Hydrocarbons
KW  - Chemical Structure
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-199258
UR  - https://doi.org/10.1021/acs.jctc.9b00029
N1  - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Theory and Computation, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see Journal of Chemical Theory and Computation 2019, 15, 6, 3450-3460. https://doi.org/10.1021/acs.jctc.9b00029.
ER  - 
TY  - INPR
A1  - Auerhammer, Nina
A1  - Schulz, Alexander
A1  - Schmiedel, Alexander
A1  - Holzapfel, Marco
A1  - Hoche, Joscha
A1  - Röhr, Merle I. S.
A1  - Mitric, Roland
A1  - Lambert, Christoph
T1  - Dynamic exciton localisation in a pyrene-BODIPY-pyrene dye conjugate
T2  - Physical Chemistry Chemical Physics
N2  - The photophysics of a molecular triad consisting of a BODIPY dye and two pyrene chromophores attached in 2-position are investigated by steady state and fs-time resolved transient absorption spectroscopy as well as by field induced surface hopping (FISH) simulations. While the steady state measurements indicate moderate chromophore interactions within the triad, the time resolved measurements show upon pyrene excitation a delocalised excited state which localises onto the BODIPY chromophore with a time constant of 0.12 ps. This could either be interpreted as an internal conversion process within the excitonically coupled chromophores or as an energy transfer from the pyrenes to the BODIPY dye. The analysis of FISH-trajectories reveals an oscillatory behaviour where the excitation hops between the pyrene units and the BODIPY dye several times until finally they become localised on the BODIPY chromophore within 100 fs. This is accompanied by an ultrafast nonradiative relaxation within the excitonic manifold mediated by the nonadiabatic coupling. Averaging over an ensemble of trajectories allowed us to simulate the electronic state population dynamics and determine the time constants for the nonradiative transitions that mediate the ultrafast energy transfer and exciton localisation on BODIPY.
KW  - Exciton localization dynamics
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-198718
UR  - https://doi.org/10.1039/C9CP00908F
N1  - Accepted manuscript
ER  -