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Combination of theoretical ab initio and experimental information to obtain reliable harmonic force constants. Scaled quantum mechanical (QM) force fields for glyoxal, acrolein, butadiene, formaldehyde, and ethylene

Pulay, Peter and Fogarasi, Géza and Pongor, Gábor and Boggs, James E. and Vargha, Anna (1983) Combination of theoretical ab initio and experimental information to obtain reliable harmonic force constants. Scaled quantum mechanical (QM) force fields for glyoxal, acrolein, butadiene, formaldehyde, and ethylene. Journal of the American Chemical Society, 105 (24). pp. 7037-7047. ISSN 0002-7863 (print), 1520-5126 (online)

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Abstract

Fully optimized geometries, complete in- and out-of-plane force fields, and dipole moment derivatives have been calculated for the title compounds at the ab initio HartreeFock level using the 4-21 Gaussian basis set. The theoretical information is combined with experimental data by fitting the calculated force constants through a few parameters to the observed frequencies to obtain the final, scaled quantum mechanical (SQM) force fields. Recommendations for a standard procedure of this type are given. The SQM force fields give excellent reproduction of the fundamental frequencies and are considered as approaching the best accuracy which can be achieved in a harmonic treatment. The infrared intensities obtained at this level of theory are only qualitative estimates, but they are still useful for making assignments more reliable.

Item Type: Article
Subjects: Q Science / természettudomány > QD Chemistry / kémia
Depositing User: Erika Bilicsi
Date Deposited: 18 Sep 2012 13:25
Last Modified: 18 Sep 2012 13:25
URI: http://real.mtak.hu/id/eprint/3009

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