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    Contribution of the empirical dispersion correction on the conformation of short alanine peptides obtained by gas-phase QM calculations


    Fadda, Elisa and Woods, Robert J. (2013) Contribution of the empirical dispersion correction on the conformation of short alanine peptides obtained by gas-phase QM calculations. Canadian Journal of Chemistry, 91 (9). pp. 859-865. ISSN 0008-4042

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    Abstract

    In this work we analyze the effect of the inclusion of an empirical dispersion term to standard DFT (DFT-D) in the prediction of the conformational energy of the alanine dipeptide (Ala2) and in assessing the relative stabilities of short polyalanine peptides in helical conformations, i.e., α and 310 helices, from Ala4 to Ala16. The Ala2 conformational energies obtained with the dispersion-corrected GGA functional B97-D are compared to previously published high level MP2 data. Meanwhile, the B97-D performance on larger polyalanine peptides is compared to MP2, B3LYP and RHF calculations obtained at a lower level of theory. Our results show that electron correlation affects the conformational energies of short peptides with a weight that increases with the peptide length. Indeed, while the contribution of vdW forces is significant for larger peptides, in the case of Ala2 it is negligible when compared to solvent effects. Even for short peptides, the inclusion of an empirical dispersion term greatly improves accuracy of DFT methods, providing results that correlate very well with the MP2 reference at no additional computational cost.

    Item Type: Article
    Keywords: alanine dipeptide; short polyalanine peptides; ab initio and DFT calculations; empirical dispersion-corrected DFT; peptides structure and stability; Ramachandran plot;
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Item ID: 7732
    Identification Number: https://doi.org/10.1139/cjc-2012-0542
    Depositing User: Elisa Fadda
    Date Deposited: 12 Jan 2017 12:13
    Journal or Publication Title: Canadian Journal of Chemistry
    Publisher: NRC Research Press
    Refereed: Yes
    Funders: Science Foundation Ireland (SFI), European Research Development Fund, National Institutes of Health (GM094919 (EUREKA))
    URI:

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