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Advances in Physical Chemistry
Volume 2011 (2011), Article ID 347072, 10 pages
http://dx.doi.org/10.1155/2011/347072
Research Article

Vibrational Study and Force Field of the Citric Acid Dimer Based on the SQM Methodology

1Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 S. M. de Tucumán, Argentina
2Cátedra de Fisicoquímica I, Instituto de Química Física, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Lorenzo 456, T4000CAN S, M. de Tucumán., Argentina
3Centro de Química Inorgánica, CEQUINOR/CCT, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115. CC. 962 (B1900AVV), 1900 La Plata, Argentina
4Laboratorio de Fisicoquímica, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Avenida Independencia 1800, T4000CAN S. M. de Tucumán., Argentina

Received 11 February 2011; Accepted 14 April 2011

Academic Editor: Joel Bowman

Copyright © 2011 Laura Cecilia Bichara et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We have carried out a structural and vibrational theoretical study for the citric acid dimer. The Density Functional Theory (DFT) method with the B3LYP/6-31G and B3LYP/6-311++ G methods have been used to study its structure and vibrational properties. Then, in order to get a good assignment of the IR and Raman spectra in solid phase of dimer, the best fit possible between the calculated and recorded frequencies was carry out and the force fields were scaled using the Scaled Quantum Mechanic Force Field (SQMFF) methodology. An assignment of the observed spectral features is proposed. A band of medium intensity at 1242  c m 1 together with a group of weak bands, previously not assigned to the monomer, was in this case assigned to the dimer. Furthermore, the analysis of the Natural Bond Orbitals (NBOs) and the topological properties of electronic charge density by employing Bader's Atoms in Molecules theory (AIM) for the dimer were carried out to study the charge transference interactions of the compound.