Abstract
First principles calculations based on density functional theory (DFT) have been combined with the multimode vibronic theory of coupled identical monomers to simulate the absorption spectra of dimers. In comparison to our previous study [J. Guthmuller et al., J. Chem. Theory Comput. 4, 2094 (2008)], where the vibrational excitations strictly accompany the electronic excitations, the vibronic model has been generalized so that the vibronic basis set contains vibrational excitations for both the ground and the excited electronic states. As a matter of illustration, this approach has been applied to a perylenetetracarboxylic diimide dimer employing a fixed dimer geometry. The exciton coupling energy is evaluated with time dependent DFT and random phase approximation calculations and by describing the effects of the solvent with the polarizable continuum model. First, the simulated monomer absorption spectrum is found to be in excellent agreement with experiment. Then, the simulated dimer absorption spectrum presents a strong dependency on the exciton coupling energy and on the inclusion of ground state vibrational excitations in the basis set. It is further shown that considering only fundamental vibrational excitations for the ground electronic state provides almost converged spectra and can therefore be used as a good first approximation. Moreover, the comparison with experiment demonstrates that the dimer absorption spectrum can be successfully reproduced by employing the exciton coupling energy determined at the time dependent DFT level provided that the effects of the solvent are included.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.