ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Coupled-cluster and many-body perturbation theories are applied to an investigation of infrared absorption intensities within the double-harmonic approximation. In agreement with previous studies, both electron correlation and basis set dependencies are found to be significant, particularly for stretching vibrations which involve hydrogen atoms. Intensities calculated at the highly correlated CCSD+T(CCSD) level with large Gaussian basis sets are in reasonable agreement with experiment for HF and the ν2 and ν3 modes of water, while the intensity of ν1 is significantly overestimated even with a relatively large 53-CGTO basis. In addition, intensities and harmonic frequencies calculated at the SCF and MBPT(2) levels with a double-zeta plus polarization (DZP) basis set are presented for a number of first row compounds, and are compared to recent experimental values. Although agreement between experimental and SCF intensities is poor, these discrepancies are moderated considerably when correlation is introduced at this simple level. The importance of including hydrogen polarization functions in the basis set is also discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.455876
