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Density Functional Theory Study of Vibrational Spectra. 1. Performance of Several Density Functional Methods in Predicting Vibrational Frequencies

Harmonic vibrational frequencies of several small organic molecules which were used to validate the scaled quantum mechanical (SQM) force field procedure of Pulay et al. were calculated using six popular density functional (DFT) methods and compared with experimental results. The combination of Becke's exchange with either Lee-Yang-Parr (BLYP) or Perdew's correlation functional (BP86) reproduces the observed frequencies satisfactorily with deviations similar to those of the Hartree-Fock SQM methods. Three hybrid DFT methods are found to yield frequencies which were generally higher than the observed fundamental frequencies. When the calculated frequencies were compared with 'experimental' harmonic frequencies however, Becke's three-parameter hybrid method with Lee-Yang-Parr correlation functional is found to be slightly more accurate, especially for C-H stretching modes. The results indicate that BLYP calculation is a very promising approach for understanding the observed spectral features.

Identiferoai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-14795
Date01 January 1996
CreatorsZhou, Xuefeng, Wheeless, Christine J.M., Liu, Ruifeng
PublisherDigital Commons @ East Tennessee State University
Source SetsEast Tennessee State University
Detected LanguageEnglish
Typetext
SourceETSU Faculty Works

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