CASPIAN JOURNAL
MANAGEMENT AND HIGH TECHNOLOGIES
The modeling of structure and system analysis of vibrational states of benzoic acid
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Read | Erman Mikhail A., Elkin Pavel M., Kartashov Maxim V., Grechukhina Oksana N. The modeling of structure and system analysis of vibrational states of benzoic acid // Caspian journal : management and high technologies. — 2012. — №3. — pp. 102-111. |
Erman Mikhail A. - post-graduate student, Astrakhan State Technical University, 18 Tatishchev st., Astrakhan, 414025, Russia,, kof@aspu.ru
Elkin Pavel M. - Ph.D. (Physics and Mathematics), Engels Technological Institute of Saratov State Technical University, 17 Svoboda sq., Engels, 413100, Russia,, kof@aspu.ru
Kartashov Maxim V. - undergraduate student, Astrakhan State University, 20a Tatishchev st., Astrakhan, 414056, Russia,, kof@aspu.ru
Grechukhina Oksana N. - Senior Lecturer, Astrakhan State University, 20a Tatishchev st., Astrakhan, 414056, Russia,, kof@aspu.ru
This work is devoted to the construction of structural and dynamic models of benzoic acid dimers. The geometric parameters of molecules such as valence bond lengths and angles between them are defined for the researched compounds. The technique for evaluation of the anharmonic shift of bands in vibrational spectra of polycyclic compounds based on the results of ab initio quantum calculations for the adiabatic potential – cubic and quartic force constants is described. The frequencies of the vibrational states and their integrated intensities are obtained. Modeling of molecular geometry and anharmonic vibrational spectra was carried out under the suggestion of planar configuration of the compounds. The calculation was performed by density functional quantum method DFT/B3LYP with different bases. A complete interpretation of the fundamental vibrational states of the compounds is carried out. The influence of polarization and diffusion effects of the atomic basis is evaluated. The analysis of the adiabatic potential parameters is carried out and the anharmonic shift of bands of vibrational spectra is evaluated. The results of the studied molecule modeling were compared with the available experimental data on vibrational spectra of the investigated compounds. One can conclude that the predictive quantum calculations of the adiabatic potential for benzoic acid is reliable and give the possibility of their spectral identification.
Key words: Vibrational spectra,Molecular spectra,IR spectra,Anharmonicity of vibrations,Benzoic acid,Benzoic acid dimers,Adiabatic potential,Intermolecular interaction,Intramolecular interaction,Force constants