TY - JOUR
T1 - Ab initio study of the excited singlet states of all-trans α,ω -diphenylpolyenes with one to seven polyene double bonds
T2 - Simulation of the spectral data within Franck-Condon approximation
AU - Mizukami, Wataru
AU - Kurashige, Yuki
AU - Ehara, Masahiro
AU - Yanai, Takeshi
AU - Itoh, Takao
N1 - Funding Information:
This research was supported in part by the Joint Studies Program (2008–2009) of the Institute for Molecular Science, the Core Research for Evolutional Science and Technology Program, “High Performance Computing for Multi-Scale and Multi-Physics Phenomena” of the Japan Science and Technology Agency (JST), and the Priority Areas for “Molecular Theory for Real Systems” (No. 461) 20038046, and Grant-in-Aid for Scientific Research (C) Grant No. 21550027 and Young Scientists (B) Grant No. 21750028 from Ministry of Education, Culture, Sports, Science and Technology-Japan (MEXT). We also acknowledge a grant of computer time at Research Center for Computational Science, Okazaki Japan, in which some of these calculations were performed. We thank Prof. H.-D. Meyer (University of Heidelberg) for kindly distributing the MCTDH program package.
PY - 2009
Y1 - 2009
N2 - Computational simulations of the electronic spectra with ab initio electronic structure calculations are presented for all-trans α,ω -diphenylpolyenes with the polyene double bond number (N) from 1 to 7. A direct comparison of the fluorescence spectra of diphenylpolyenes was made between the results of highly accurate calculations and the experimental data for the systems with various chain lengths. For the realistic simulation of the emission, the total vibrational wave function was described approximately as a direct product of one-dimensional (1D) vibrational wave functions along the normal coordinates that are determined from the vibrational analysis of the ground state. The observed spectra can be reproduced in a computationally efficient way by selecting effective C-C and C=C stretching modes for the constructions of the 1D vibrational Hamiltonians. The electronic structure calculations were performed using the multireference Møller-Plesset perturbation theory with complete active space configuration interaction reference functions. Based on the vertical excitation energies computed, the lowest singlet excited state of diphenylbutadiene is shown to be the optically forbidden 21 A g state. The simulations of fluorescence spectra involving vibronic coupling effects reveal that the observed strong single C=C band consists of two major degenerate vibrational C=C modes for the shorter diphenylpolyenes with N=3 and 5. Further, the relative intensities of the C-C stretching modes in the fluorescence spectra tend to be larger than those of the C=C stretching modes for the systems with N over 5. This indicates that the geometric differences of the energy minima between the ground (1 1 A g) and 21Ag states grow larger towards the direction of the C-C stretching mode with increasing N.
AB - Computational simulations of the electronic spectra with ab initio electronic structure calculations are presented for all-trans α,ω -diphenylpolyenes with the polyene double bond number (N) from 1 to 7. A direct comparison of the fluorescence spectra of diphenylpolyenes was made between the results of highly accurate calculations and the experimental data for the systems with various chain lengths. For the realistic simulation of the emission, the total vibrational wave function was described approximately as a direct product of one-dimensional (1D) vibrational wave functions along the normal coordinates that are determined from the vibrational analysis of the ground state. The observed spectra can be reproduced in a computationally efficient way by selecting effective C-C and C=C stretching modes for the constructions of the 1D vibrational Hamiltonians. The electronic structure calculations were performed using the multireference Møller-Plesset perturbation theory with complete active space configuration interaction reference functions. Based on the vertical excitation energies computed, the lowest singlet excited state of diphenylbutadiene is shown to be the optically forbidden 21 A g state. The simulations of fluorescence spectra involving vibronic coupling effects reveal that the observed strong single C=C band consists of two major degenerate vibrational C=C modes for the shorter diphenylpolyenes with N=3 and 5. Further, the relative intensities of the C-C stretching modes in the fluorescence spectra tend to be larger than those of the C=C stretching modes for the systems with N over 5. This indicates that the geometric differences of the energy minima between the ground (1 1 A g) and 21Ag states grow larger towards the direction of the C-C stretching mode with increasing N.
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U2 - 10.1063/1.3261729
DO - 10.1063/1.3261729
M3 - Article
C2 - 19895018
AN - SCOPUS:70449382063
VL - 131
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 17
M1 - 174313
ER -