TY - JOUR
T1 - Multimode simulation of dimer absorption spectra from first principles calculations
T2 - Application to the 3,4,9,10-perylenetetracarboxylic diimide dimer
AU - Guthmuller, Julien
AU - Zutterman, Freddy
AU - Champagne, Benoit
PY - 2009/11/17
Y1 - 2009/11/17
N2 - 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, 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.
AB - 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, 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.
UR - http://www.scopus.com/inward/record.url?scp=70449393966&partnerID=8YFLogxK
U2 - 10.1063/1.3245403
DO - 10.1063/1.3245403
M3 - Article
AN - SCOPUS:70449393966
SN - 0021-9606
VL - 131
JO - The Journal of chemical physics
JF - The Journal of chemical physics
IS - 15
M1 - 154302
ER -