The Molecular Structure of 1,3-Butadiene and 1,3,5-trans-Hexatriene.

Haugen, William; Trætteberg, M.; Kaufmann, Frantz; Motzfeldt, K.; Williams, Dudley H.; Bunnenberg, E.; Djerassi, Carl; Records, Ruth

doi:10.3891/acta.chem.scand.20-1726

Cited by 171 publications

(74 citation statements)

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“…4 The computed excitation energies have the same accuracy as that obtained here. Even though these calculations are carried to third order in the treatment of dynamic correlation, they provide further evidence for the validity of a low order multiconfigurational perturbation approach in calculations of electronic excitation energies.…”

Section: Discussionsupporting

confidence: 70%

“…However, one problem with most of the ab initio studies is that they overestimate the excitation energy for the 1 'B, with several tenths of an eV. Only a very recent study by Graham and Freed,4 gives an excitation energy for this state in reasonable agreement with experiment [6.14 eV compared to an experimental value for the band maximum of 5.92 eV . Their value for the vertical excitation energy of 2 'Ag is 6.19 eV, which places the two bands on top of each other.…”

Section: Introductionmentioning

confidence: 53%

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Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene

Serrano‐Andrés

Merchán

Nebot–Gil

et al. 1993

The Journal of Chemical Physics

428

408

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A newly proposed quantum chemical approach for ab initio calculations of electronic spectra of molecular systems is applied to the molecules ethene, trans-1,3-butadiene, and transtrans-1,3,5-hexatriene. The method has the aim of being accurate to better than 0.5 eV for excitation energies and is expected to provide structural and physical data for the excited states with good reliability. The approach is based on the complete active space (CAS) SCF method, which gives a proper description of the major features in the electronic structure of the excited state, independent of its complexity, accounts for all near degeneracy effects, and includes full orbital relaxation. Remaining dynamic electron correlation effects are in a subsequent step added using second order perturbation theory with the CASSCF wave function as the reference state. The approach is here tested in a calculation of the valence and Rydberg excited singlet and triplet states of the title molecules, using extended atomic natural orbital (ANO) basis sets. The ethene calculations comprised the two valence states plus all singlet and triplet Rydberg states of 3s, 3p, and 3d character, with errors in computed excitation energies smaller than 0.13 eV in all cases except the V state, for which the vertical excitation energy was about 0.4 eV too large. The two lowest triplet states and nine singlet states were studied in butadiene. The largest error (0.37 eV) was found for the 2 'B, state. The two lowest triplet and seven lowest singlet states in hexatriene had excitation energies in error with less than 0.17 eV.

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Section: Discussionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 53%

Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene

Serrano‐Andrés

Merchán

Nebot–Gil

et al. 1993

The Journal of Chemical Physics

428

408

View full text Add to dashboard Cite

show abstract

“…In the SM, Figure S20 and Table S11 l m is shown to become nearly constant near the chain centers at large N. Here, the geometry is quite close to experimental findings 53 for the infinite chain (cf. SM) such that OM2/DCI(π ) geometries are reasonable at large N. For N = 4 the OM2/DCI(π ) bond lengths differ from the experimental values 54 by a root mean square deviation of 0.007 Å. Thus, the OM2/DCI(π ) polyene geometries should be reasonable for all N.…”

Section: Om2 Optimized Geometriesmentioning

confidence: 99%

Electronic excitations in long polyenes revisited

Schmidt

Tavan

2012

The Journal of Chemical Physics

106

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We apply the valence shell model OM2 [W. Weber and W. Thiel, Theor. Chem. Acc. 103, 495, (2000)] combined with multireference configuration interaction (MRCI) to compute the vertical excitation energies and transition dipole moments of the low-energy singlet excitations in the polyenes with 4 ≤ N ≤ 22π -electrons. We find that the OM2/MRCI descriptions closely resemble those of Pariser-Parr-Pople (PPP) π -electron models [P. Tavan and K. Schulten, Phys. Rev. B 36, 4337, (1987)], if equivalent MRCI procedures and regularly alternating model geometries are used. OM2/MRCI optimized geometries are shown to entail improved descriptions particularly for smaller polyenes (N ≤ 12), for which sizeable deviations from the regular model geometries are found. With configuration interaction active spaces covering also the σ -in addition to the π -electrons, OM2/MRCI excitation energies turn out to become smaller by at most 0.35 eV for the ionic and 0.15 eV for the covalent excitations. The particle-hole (ph) symmetry, which in Pariser-Parr-Pople models arises from the zero-differential overlap approximation, is demonstrated to be only weakly broken in OM2 such that the oscillator strengths of the covalent 1B − u states, which artificially vanish in ph-symmetric models, are predicted to be very small. According to OM2/MRCI and experimental data the 1B − u state is the third excited singlet state for N < 12 and becomes the second for N ≥ 14. By comparisons with results of other theoretical approaches and experimental evidence we argue that deficiencies of the particular MRCI method employed by us, which show up in a poor size consistency of the covalent excitations for N > 12, are caused by its restriction to at most doubly excited references.

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“…3 We made this choice to facilitate easier comparison with previous studies, but the choice of geometry could potentially affect the results on a scale of 0.1 eV, so we explored two other theoretically optimized geometries in addition. In particular, assuming C 2v symmetry, we optimized the geometry at the MP2/cc-pVQZ and CCSD(T)/aug-cc-pVQZ levels of theory using the MOLPRO quantum chemistry package.…”

Section: Molecular Geometriesmentioning

confidence: 99%

Excited States of Butadiene to Chemical Accuracy: Reconciling Theory and Experiment

Watson

Chan

2012

J. Chem. Theory Comput.

104

121

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We obtain the vertical excitation energies of the notoriously challenging lowest-lying dark and bright excitations of trans-butadiene to chemical accuracy using high-order equation-of-motion coupled-cluster theory. Convergence is demonstrated in both the one-particle basis set (up to augmented quintuple-zeta quality) and the coupled-cluster expansion (including up to connected quadruple excitations) within an incremental scheme. Our best estimates for the bright 1 1 B u + and dark 2 1 A g − vertical transitions are 6.21 ± 0.02 eV and 6.39 ± 0.07 eV, respectively, establishing definitively that the vertical 1 1 B u + transition lies below the 2 1 A g − transition. Our 1 1 B u + excitation energy remains significantly higher than the generally cited experimental value of 5.92 eV. To rationalize this difference, we have computed the zero-point vibrational energy corrections, which reduce the theoretical 1 1 B u + excitation energy to 6.11 eV. We also correct for nonverticality in the experimental value by recomputing the transition as the weighted intensity average of the electron impact energy loss spectra, which gives the range 5.96−6.05 eV. The corrected best theoretical and experimental 1 1 B u + excitation energies are then in good agreement, resolving a long-standing discrepancy.Letter pubs.acs.org/JCTC

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The Molecular Structure of 1,3-Butadiene and 1,3,5-trans-Hexatriene.

Cited by 171 publications

References 0 publications

Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene

Towards an accurate molecular orbital theory for excited states: Ethene, butadiene, and hexatriene

Electronic excitations in long polyenes revisited

Excited States of Butadiene to Chemical Accuracy: Reconciling Theory and Experiment

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