Regularizing algorithm for determination of equilibrium geometry and harmonic force field of free molecules from joint use of electron diffraction, vibrational spectroscopy and ab initio data with application to benzene

Кочиков, И. В.; Tarasov, Yu. I.; Kuramshina, G. M.; Spiridonov, V. P.; Yagola, A. G.; Strand, T. G.

doi:10.1016/s0022-2860(97)00428-6

Cited by 48 publications

(25 citation statements)

References 15 publications

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“…General molecular model is applicable to both spectroscopic and structural studies making possible their joint treatment. This approach presupposing analysis of the molecular Hamiltonian and adiabatic separation of different molecular degrees of freedom was initially developed for semirigid molecular systems with SAM and later extended to nonrigid polyatomic molecules with one or more coordinates of LAM [51][52][53][54][55][56]. The basic idea of subdividing molecular translations, rotations, and vibrations is supplemented with rigorous adiabatic separation of the LAM coordinates.…”

Section: Struct Chemmentioning

confidence: 99%

“…[73,74]. Structural analysis of the GED data jointly with the spectroscopic experimental data and quantum chemical calculation results has been performed with the SYMM/DISP/ELDIFF/LARGE software package [51][52][53][54][55][56], whose molecular model is based entirely on the parameters of the PES and advantage of which in the investigation of structure of flexible molecules is briefly characterized above. The necessary ab initio calculations, including the calculation of quadratic and cubic force constants, have been performed by the MP2(full) method using the aug-cc-pVTZ and ccpVTZ basis sets.…”

Section: By Thementioning

confidence: 99%

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IR spectra of nitrobenzene and nitrobenzene-15N in the gas phase, ab initio analysis of vibrational spectra and reliable force fields of nitrobenzene and 1,3,5-trinitrobenzene. Investigation of equilibrium geometry and internal rotation in these simplest aromatic nitro compounds with one and three rotors by means of electron diffraction, spectroscopic, and quantum chemistry data

et al. 2015

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The IR spectra of gaseous nitrobenzene (NB) and its 15 N isotopomer have been obtained in the frequency range of 3500-250 cm -1 , and the far-IR spectra of their solutions and the NB neat liquid sample have been recorded in the range of 600-30 cm -1 . A detailed description of the spectra of NB and 1,3,5-trinitrobenzene (sym-TNB) and their isotopomers has been accomplished using the force fields calculated at the MP2(full)/aug-cc-pVTZ and MP2(full)/cc-pVTZ levels. Transferability of the refined scale factors for the calculated force constants obtained by the Pulay technique has been used to provide evidence for validity of both interpreting the NB and sym-TNB spectra and refining the calculated force fields. The direct and inverse spectral problems have been solved by variational technique to determine torsional energy levels and refine the potential function by optimizing the V k coefficients in its Fourier series expansion. The height of the MP2(full) barrier to internal rotation has been reduced from 5.5 to 4.5 kcal/mol due to extension of the used basis set from 6-31(d,p) to aug-cc-pVTZ. The method of joint dynamic structural analysis of the GED, MW, and vibrational spectroscopy, and ab initio data in terms of the PES parameters have been applied to investigation of equilibrium geometry and internal rotation in the nonrigid NB and sym-TNB molecules having one and three coupled internal rotors, respectively. The experimental r e -parameter values of both molecules (C 2v and D 3h point group symmetries) are in agreement with those obtained by ab initio calculations. This paper is dedicated to Professor Magdolna Hargittai on the occasion of her 70th birthday.

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Section: Struct Chemmentioning

confidence: 99%

Section: By Thementioning

confidence: 99%

IR spectra of nitrobenzene and nitrobenzene-15N in the gas phase, ab initio analysis of vibrational spectra and reliable force fields of nitrobenzene and 1,3,5-trinitrobenzene. Investigation of equilibrium geometry and internal rotation in these simplest aromatic nitro compounds with one and three rotors by means of electron diffraction, spectroscopic, and quantum chemistry data

et al. 2015

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“…14,15 In both cases a theoretical model is required. A direct problem is basically a simple comparison of experimental data with that computed from the model.…”

Section: 13mentioning

confidence: 99%

“…15 VM -the parameters were computed using the VibModule program. 76 It is a new implementation of Sipachev's Shrink software.…”

Section: 75mentioning

confidence: 99%

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Application of classical simulations for the computation of vibrational properties of free molecules

Tikhonov

Sharapa

Schwabedissen

et al. 2016

Phys. Chem. Chem. Phys.

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In this study, we investigate the ability of classical molecular dynamics (MD) and Monte-Carlo (MC) simulations for modeling the intramolecular vibrational motion. These simulations were used to compute thermally-averaged geometrical structures and infrared vibrational intensities for a benchmark set previously studied by gas electron diffraction (GED): CS 2 , benzene, chloromethylthiocyanate, pyrazinamide and 9,12-I 2 -1,2-closo-C 2 B 10 H 10 . The MD sampling of NVT ensembles was performed using chains of Nose-Hoover thermostats (NH) as well as the generalized Langevin equation thermostat (GLE). The performance of the theoretical models based on the classical MD and MC simulations was compared with the experimental data and also with the alternative computational techniques: a conventional approach based on the Taylor expansion of potential energy surface, path-integral MD and MD with quantum-thermal bath (QTB) based on the generalized Langevin equation (GLE). A straightforward application of the classical simulations resulted, as expected, in poor accuracy of the calculated observables due to the complete neglect of quantum effects. However, the introduction of a posteriori quantum corrections significantly improved the situation. The application of these corrections for MD simulations of the systems with large-amplitude motions was demonstrated for chloromethylthiocyanate. The comparison of the theoretical vibrational spectra has revealed that the GLE thermostat used in this work is not applicable for this purpose. On the other hand, the NH chains yielded reasonably good results.

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Inter‐ and Intramolecular Aryl–Aryl Interactions in Partially Fluorinated Ethylenedioxy‐bridged Bisarenes**

Weddeling

Vishnevskiy

Neumann

et al. 2020

Chemistry A European J

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Several ethylenedioxy-bridged bisarenes with a variety of type and number of aryl groups were synthesized to study non-covalent dispersion-driven inter-and intramolecular aryl-aryl-interactions in the solid state and gas phase. Intramolecular interactions are preferably found in the gas phase. DFT calculations of dispersion-corrected energy scans for rotations around the ethylenedioxy-bridge and optimized structures show larger interacting aromatic groups to increase the dispersion energy. Single molecule structures generally adopt folded conformations with short intramolecular aryl-aryl-contacts. Gas electron diffraction experiments were performed exemplarily for 1-(pentafluorophenoxy)-2-(phenoxy)ethane. A new procedure for structure refinement was developed to deal with the conformational complexity of such molecules. The results are an experimental confirmation of the existence of folded conformations of this molecule with short-intramolecular aryl-aryl distances in the gas phase. Solid-state structures are dominated by stretched structures without intramolecular aryl-aryl-interactions but interactions with neighboring molecules.

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Regularizing algorithm for determination of equilibrium geometry and harmonic force field of free molecules from joint use of electron diffraction, vibrational spectroscopy and ab initio data with application to benzene

Cited by 48 publications

References 15 publications

Application of classical simulations for the computation of vibrational properties of free molecules

Inter‐ and Intramolecular Aryl–Aryl Interactions in Partially Fluorinated Ethylenedioxy‐bridged Bisarenes**

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