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Basis set effects and the choice of reference geometry in ab initio calculations of vibrational spectra

✍ Scribed by D. Michalska; L. J. Schaad; P. C̆arsky; B. Andes Hess Jr.; C. S. Ewig

Publisher
John Wiley and Sons
Year
1988
Tongue
English
Weight
876 KB
Volume
9
Category
Article
ISSN
0192-8651

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✦ Synopsis

Tatewaki and Huzinaga's [J. Comput. Chem. 1, 205 (198011 basis sets, constructed to minimize superposition error, were used to calculate infrared (IR) frequencies and intensities. They were found inferior to Pople bases such as 3-21G and 6-31G*. The question of whether a theoretical vibrational spectrum should be computed a t experimental or theoretical bond lengths was also investigated. If the magnitude of the correlation energy increases with bond length, Hartree-Fock bond lengths are expected to be shorter than experimental, and frequencies computed there will be higher than those computed at experimental lengths. Conversely, if this magnitude decreases with R, computed lengths should be longer than experimental and should give lower computed frequencies.

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