A theoretical study of the 1B2u and 1B1u vibronic bands in benzene

Bernhardsson, Anders; Forsberg, Niclas; Malmqvist, Per-A. ̊Ke; Roos, Björn O.; Serrano‐Andrés, Luis

doi:10.1063/1.480854

Cited by 90 publications

(110 citation statements)

References 41 publications

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“…The same behavior was observed in earlier investigations. 3 Hence, there will be some sequences 1 0 ' 1 of the modes n 4 , n 10 , n 11 , n 16 , and n 17 . Thus, the hot bands associated with 6 1 0 were constructed including two progressions and five sequences, …”

Section: Spectrum Simulationmentioning

confidence: 99%

“…They considered the temperature effect, the anharmonic effect, the Duschinsky effect and so on. Roos et al 3 also presented simulation on the vibronic spectra of this transition. However, theoretical research for IC of benzene is still rare.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the first derivatives of the transition dipole moment along the normal coordinates can be directly calculated by the finite difference method. Roos et al 3 expressed the wave functions as a function of a perturbation strength to obtain derivatives of the transition properties, and then employ this method to calculate the vibronic coupling for symmetry-forbidden transitions in benzene. Borges et al 4 expanded the transition dipole moments as a power series assuming that the total transition dipole moment is the sum of the transition dipole moments along each participating mode.…”

Section: Introductionmentioning

confidence: 99%

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Symmetry forbidden vibronic spectra and internal conversion in benzene

Lin

et al. 2010

Phys. Chem. Chem. Phys.

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The spectra of symmetry-forbidden transitions and internal conversion were investigated in the present work. Temperature dependence was taken into account for the spectra simulation. The vibronic coupling, essential in the two processes, was calculated based on the Herzberg-Teller theory within the Born-Oppenheimer approximation. The approach was employed for the symmetry-forbidden absorption/fluorescence, and internal conversion between 1 1 A 1g and 1 1 B 2u states in benzene. Vibrational frequencies, normal coordinates, electronic transition dipole moments, and non-adiabatic coupling matrix elements were obtained by ab initio quantum chemical methods. The main peaks, along with the weak peaks, were in good agreement with the observed ones. The rate constant of the 1 1 A 1g ' 1 1 B 2u internal conversion was estimated within the order of 10 3 s À1 . This could be regarded as the lower limit (about 4.8 Â 10 3 s À1 ) of the internal conversion. It is stressed that the distortion effect was taken into account both in the symmetry-forbidden absorption/fluorescence, and the rate constants of internal conversion in the present work. The distortion effects complicate the spectra and increase the rate constants of internal conversion.

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Section: Spectrum Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Symmetry forbidden vibronic spectra and internal conversion in benzene

Lin

et al. 2010

Phys. Chem. Chem. Phys.

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“…The valence transitions 1 1 B 2u ←X and 1 1 B 1u ←X, symmetry forbidden, appear with considerable intensity in the optical spectrum due to vibronic coupling. Several theoretical studies investigated one or both transitions, using perturbation theory [6,14,36], and/or including the Duchinsky effect [37][38][39][40]. The older works have mostly used semiempirical wave functions, while the more recent ones employed Complete Active Space Self Consistent Field (CASSCF) electronic wave functions.…”

Section: A Benzene C 6 Hmentioning

confidence: 99%

“…The electronic wave function used was a CASSCF(6,6)/ccpvdz which was built from six valence π orbitals and 6 electrons, perfectly adequate to describe these π → π transitions [40]. The molecular orbitals to calculate the transition dipole moments were state averaged for each transition, an approach that improves the accuracy of the transition dipole moments by providing a balanced description of each pair of states [41].…”

Section: A Benzene C 6 Hmentioning

confidence: 99%

Theoretical investigations on valence vibronic transitions

Borges¹,

Rocha²,

Bielschowsky³

2005

Braz. J. Phys.

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This article reviews previously employed methods to study several valence electronic transitions, optically forbidden or not, enhancing intensity through vibronic coupling. Electronic transition dipole moments were calculated using several ab initio methods including electron correlation. In this method the square of the electronic transition dipole moments are directly calculated along the normal coordinates of vibration and then expanded with a polynomial function. Afterwards, analytical vibrational integration using harmonic wave functions, of the square of the transition moments function, allows us to obtain partial (i.e. for each vibrational mode) and total optical oscillator strengths (OOS), for the vibronic transition of interest. We illustrate the accuracy of the method through valence transitions of benzene (C 6 H 6 ), formaldehyde (H 2 CO), acetone (C 3 H 6 O) and formic acid (HCOOH).

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Spectroscopy: Applications

Serrano-Andr��s¹,

Merch��n²

1998

Encyclopedia of Computational Chemistry

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Recent years have seen an extraordinary development in the applicability and accuracy of ab initio methods to compute molecular excited states, which are now generally determined with a precision of 0.1–0.2 eV. The size and character of the problems have increased to make the calculations competitive and complementary to the experimental determinations involving medium and large molecular systems. Many examples can be provided of this new era in the quantum chemistry of the excited state where the multiconfigurational methods, in particular, CASPT2, have been the main protagonists. The present article contains an account of the types and nature of excited states, a compilation of methods, strategies, and problems to be solved in the calculation of molecular excited states, particularly to obtain electronic transition energies and properties, such as band intensities and state lifetimes. Finally, a number of examples and achievements in the field give an overall view of what can be computed nowadays and how the computations can be performed. Illustrative examples include the calculation of dark states, vibrational resolution of electronic bands, novel assignments, interplay between theoretical spectroscopy and experiment, and adiabatic and nonadiabatic photochemical processes.

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A theoretical study of the 1B2u and 1B1u vibronic bands in benzene

Cited by 90 publications

References 41 publications

Symmetry forbidden vibronic spectra and internal conversion in benzene

Symmetry forbidden vibronic spectra and internal conversion in benzene

Theoretical investigations on valence vibronic transitions

Spectroscopy: Applications

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