An ab initio study of the cis-trans photoisomerization of stilbene

Orlandi, Giorgio; Palmieri, Paolo; Poggi, Gabriella

doi:10.1021/ja00507a012

Cited by 109 publications

(43 citation statements)

References 3 publications

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“…This is also true of calculations on longer oligomers and the polymers themselves. ͑In this discussion we omit any weak particle-hole forbidden transitions, referring for the moment only to the strong absorption bands.͒ Semiempirical models that directly include the electrons sometimes work, 9,10 and sometimes do not. 2,11 This is probably due partly to poor parameterization, and partly to incomplete treatment of correlation effects.…”

Section: Introductionmentioning

confidence: 99%

Screening and the quantitative π-model description of the optical spectra and polarizations of phenyl based oligomers

Castleton

Barford

2002

The Journal of Chemical Physics

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The long standing problem of the inability of many semiempirical models to correctly predict the polarization of the higher dipole allowed optical transitions of phenyl based -conjugated polymers and molecules is examined and related to the issue of internal and external screening ofelectron Coulomb interactions within the molecules. Following a review of previous theoretical and experimental work, electron only the Complete Neglect of Differential Overlap ͑CNDO͒ model is presented which, for the first time, is able to predict accurately the energies and symmetries of all the observed optical transitions of benzene, biphenyl and trans-stilbene, up to ϳ8 -10 eV. In so doing, it is demonstrated that the problem with previous calculations was the noninclusion of screening from outside the electron system itself. By fitting separately the spectra in hydrocarbon based condensed phases, in the gas phase and in solid rare gas matrices, and comparing the resulting model parameters, we show that, while the effects of screening from the environment are certainly noticeable, the most important spectral features-in particular the ordering of dipole allowed transitions-come from effective screening by the electrons. We find that both of these effects can be adequately accounted for within a electron only model by using a dielectric constant and appropriate parameter renormalization.

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Section: Introductionmentioning

confidence: 99%

Screening and the quantitative π-model description of the optical spectra and polarizations of phenyl based oligomers

Castleton

Barford

2002

The Journal of Chemical Physics

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“…[14][15][16][17][18][19] In an adiabatic model, 14,15 see Fig. 1, one assumes the existence of a small barrier on the first excited state ͑S 1 ͒ and fast intramolecular vibrational energy redistribution ͑IVR͒, so that the Rice-RamspergerKassel-Marcus ͑RRKM͒ model can be used to calculate the reaction rate.…”

Section: Basic Assumptionsmentioning

confidence: 99%

“…In particular, at low pressures the theoretical model fits reasonably well to the experimental data, 23,24 but at pressures above 5 bar the experimental rate constant levels off at 20-30 ns −1 , while the theoretical high-pressure limit 24 is at 76 ns −1 . Alternatively, a nonadiabatic model involving the transition to another excited state was suggested [16][17][18][19] in order to explain the photoisomerization mechanism. This model is supported by the fact that the twisted conformation of stilbene, where the radiationless transition to the ground state takes place, belongs to the distinct electronic state ͑S 2 ͒ characterized as the doubly excited or zwitterionic state.…”

Section: Basic Assumptionsmentioning

confidence: 99%

“…This model is supported by the fact that the twisted conformation of stilbene, where the radiationless transition to the ground state takes place, belongs to the distinct electronic state ͑S 2 ͒ characterized as the doubly excited or zwitterionic state. [16][17][18][19] The origin of the small barrier in the adiabatic model for the twist around the central ethylenic bond, which is also assumed to be the reaction coordinate, is not clear. A bond length is typically a good qualitative measure for the electron density located on it and for the associated barrier height of the torsional motion around it.…”

Section: Basic Assumptionsmentioning

confidence: 99%

“…The latter excited state is recognized to play a fundamental role in the process of photoisomerization of trans-stilbene, as the radiationless transition into the ground state takes place in the twisted conformation characterized as the double excited one. [16][17][18][19] Then the geometries for the excited states of interest have been optimized and the calculations have been repeated. The results are summarized in Table III.…”

Section: Estimation Of the Relative Energetics Of The Pess For Tramentioning

confidence: 99%

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Quantum-classical modeling of photoisomerization of polyatomic molecules

Tranca

Neufeld

2010

The Journal of Chemical Physics

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Quantum dynamics study of fulvene double bond photoisomerization: The role of intramolecular vibrational energy redistribution and excitation energy J. Chem. Phys. 135, 134303 (2011) A new method, non-Markovian quantum-classical approximation ͑NQCA͒, is suggested to model the photoisomerization of polyatomic molecules. The NQCA method can be successfully applied to follow the photoisomerization process for a wide class of reacting systems, namely, those for which the time scale required for the equilibration in the phase space of the potential energy surface ͑PESs͒ is short compared to the time scale of the transitions between them. Such a situation is quite typical for the nonadiabatic transitions between the different electronic states in polyatomic molecules, where a high density of vibronic states facilitates the intramolecular vibrational energy redistribution, thus providing an efficient relaxation for the phase space distribution. The NQCA can easily be combined with molecular dynamics and quantum-chemical methods to describe the evolution of the classical degrees of freedom and the quantum part of the problem.

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Density Functional Studies of the Ground- and Excited-State Potential-Energy Curves of Stilbenecis-trans Isomerization

et al. 2002

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Using spin‐unrestricted density functional theory (the VWN Becke–Perdew potential), including broken‐symmetry and spin‐projection methods, we have obtained the potential‐energy curves as a function of the central torsional angle of stilbene in the ground (S0), the first excited triplet (T1), the first excited singlet (S1), and the doubly excited singlet (S2) states. The thermal trans→cis isomerization of stilbene passes through a diradical broken‐symmetry electronic structure around the twisted conformation (90° central torsional angle) in the ground state. Our calculations support the proposed triplet mechanism for sensitized cis⇌trans photoisomerization and the nonadiabatic singlet mechanism proposed by Orlandi and Siebrand.1 On the T1 potential‐energy curve, the rotation of the C=C bond for both trans‐ and cis‐stilbene will lead stilbene to the twisted conformation, from which the twisted stilbene will decay to the ground‐state surface that is nearly isoenergetic with the T1 surface and has diradical electronic structure in the twisted region. On the S1 potential‐energy curve, the energy increases in the direction from trans‐ to the twisted stilbene, and crosses with the neutral doubly excited S2 potential‐energy curve, which has a minimum at the twisted structure and is lower in energy than the zwitterionic doubly excited state. The twisted stilbene around the energy minimum of the neutral doubly excited S2‐state will decay onto the ground‐state surface from where the rotation of the C=C bond leads the twisted stilbene to either the trans or cis configuration and the isomerization of stilbene is then completed. Similar studies have also been performed on a stilbene derivative with a substituent group, NHCOCH3.

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An ab initio study of the cis-trans photoisomerization of stilbene

Cited by 109 publications

References 3 publications

Screening and the quantitative π-model description of the optical spectra and polarizations of phenyl based oligomers

Screening and the quantitative π-model description of the optical spectra and polarizations of phenyl based oligomers

Quantum-classical modeling of photoisomerization of polyatomic molecules

Density Functional Studies of the Ground- and Excited-State Potential-Energy Curves of Stilbenecis-trans Isomerization

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