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Updated: Jul 15, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Calculation of vibrational infrared intensities and Raman activities using explicit anharmonic wave functions
Peter Seidler1, Jacob Kongsted, Ove Christiansen
1The Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus C, Denmark. seidler@chem.au.dk
Abstract:
Methods for automatic computation of IR intensities and Raman activities are described using vibrational self-consistent field (VSCF) and vibrational configuration interaction (VCI) wave functions. Inclusion of effects due to anharmonicity in the potential energy and property surfaces are found to improve the results substantially as compared to experimental data. Sample calculations employing water and formaldehyde are presented, allowing for comparison between different vibrational methods. The convergence with respect to excitation level in VCI and the extent of mode coupling in the potential and property expansions is investigated. In addition, different electronic methods used for generating the potential and property surfaces, namely CCSD, CCSD(T), DFT/B3LYP, and DFT/CAM-B3LYP have been compared. Details of the potential and property surfaces may have significant effects on the IR and Raman intensities.
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