Fast vibrational calculation of anharmonic OH-stretch frequencies for two low-energy noradrenaline conformers

Benoit, David M.

Abstract

We introduce a new reduced-coupling technique to accelerate direct calculations of a selected number of vibrational frequencies in large molecular systems. Our method combines the advantages of the single-to-all correlation-corrected vibrational self-consistent field (STA-CC-VSCF) approach [D. M. Benoit, J. Chem. Phys. 125, 244110 (2006)] with those of the fast-CC-VSCF technique [D. M. Benoit, J. Chem. Phys. 120, 562 (2004)] and allows the ab initio calculation of only the relevant parts of the required potential energy surface (PES). We demonstrate, using a set of five aliphatic alcohol molecules, that the new fast-STA-CC-VSCF method is accurate and leads to very substantial time gains for the computations of the PES. We then use the fast-STA-CC-VSCF method to accelerate the computation of the OH-stretch and NH-stretch frequencies of the two lowest-energy conformers of noradrenaline, namely, AG1a and GG1a. Our new approach enables us to run the calculation 89 times faster than the standard CC-VSCF technique and makes it possible to use a high-level MP2/TZP description of the PES. We demonstrate that the influence of the strong mode-mode couplings is crucial for a realistic description of the particular OH-stretch vibrational signature of each conformer. Finally, of the two possible low-energy conformers, we identify AG1a as the one most likely to have been observed in the experiments of Snoek [Mol. Phys. 101, 1239 (2003)].

Citation

Benoit, D. M. (2008). Fast vibrational calculation of anharmonic OH-stretch frequencies for two low-energy noradrenaline conformers. The Journal of chemical physics, 129(23), Article 234304. https://doi.org/10.1063/1.3040427

• Journal Article Type: Article
• Acceptance Date: Nov 1, 2008
• Online Publication Date: Dec 16, 2008
• Publication Date: Dec 21, 2008
• Deposit Date: Nov 13, 2014
• Publicly Available Date: Nov 13, 2014
• Journal: Journal of chemical physics
• Print ISSN: 0021-9606
• Publisher: American Institute of Physics
• Peer Reviewed: Peer Reviewed
• Volume: 129
• Issue: 23
• Article Number: 234304
• DOI: https://doi.org/10.1063/1.3040427
• Keywords: Physical and Theoretical Chemistry; General Physics and Astronomy
• Public URL: https://hull-repository.worktribe.com/output/462184
• Publisher URL: http://scitation.aip.org/content/aip/journal/jcp/129/23/10.1063/1.3040427
• Additional Information: Copy of article: Fast vibrational calculation of anharmonic OH-stretch frequencies for two low-energy noradrenaline conformers Benoit, David M., The Journal of Chemical Physics, 129, 234304 (2008), DOI:http://dx.doi.org/10.1063/1.3040427
• Contract Date: Nov 13, 2014