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  - Petersen, Jens
A1  - Lindner, Joachim O.
A1  - Mitric, Roland
T1  - Ultrafast Photodynamics of Glucose
T2  - Journal of Physical Chemistry B
N2  - We have investigated the photodynamics of \(\beta\)-D-glucose employing our field-induced surface hopping method (FISH), which allows us to simulate the coupled electron-nuclear dynamics, including explicitly nonadiabatic effects and light-induced excitation. Our results reveal that from the initially populated S\(_{1}\) and S\(_{2}\) states, glucose returns nonradiatively to the ground state within about 200 fs. This takes place mainly via conical intersections (CIs) whose geometries
in most cases involve the elongation of a single O-H bond, while in some instances ring-opening due to dissociation of a C-O bond is observed. Experimentally, excitation to a distinct excited electronic state is improbable due to the presence of a dense manifold of states bearing similar oscillator strengths. Our FISH simulations explicitly including a UV laser pulse of 6.43 eV photon energy reveals that after initial excitation the population is almost equally spread over several close-lying electronic states. This is followed by a fast nonradiative decay on the time scale of 100-200 fs, with the final return to the ground state proceeding via the S\(_{1}\) state through the same types of CIs as observed in the field-free simulations.
KW  - photodynamics
KW  - nonadiabatic dynamics
KW  - conical intersections
KW  - carbohydrates
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159155
N1  - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry, copyright © American Chemical Society after peer review. To access the final edited and published work see doi:10.1021/acs.jpcb.7b08602
ER  -