The complete harmonic force field of pyrimidine has been computed at the ab initio Hartree-Fock level using a 4-21 Gaussian basis set. In order to compensate the systematic overestimations of the force constants at the aforementioned level of quantum mechanical approximation, the theoretical force c
Scaled quantum mechanical computations of vibrational spectra of organoelement molecules, containing the atoms P, S, and Cl
✍ Scribed by Sergey Katsyuba; Elena Vandyukova
- Publisher
- Elsevier Science
- Year
- 2003
- Tongue
- English
- Weight
- 176 KB
- Volume
- 377
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Density functional theory has been used for the calculation of vibrational force fields of organoelement molecules. Optimal scaling factors for various stretching and bending force constants are derived from a training set of 12 molecules, containing H, C, N, O, P, S, and Cl atoms, and used to scale force constants for further 14 molecules. These 13 scaling factors, applied to B3LYP force fields, allow compute the 310 frequencies of 26 molecules with the total standard deviation of about 11 cm À1 for 6-31G* and 6-31+G* basis sets, the latter set being preferable for computations of Raman spectra.
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