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Analytical nuclear gradients for the range-separated many-body dispersion model of noncovalent interactions

Author(s): Blood-Forsythe, Martin A.; Markovich, Thomas; DiStasio, Robert A. Jr; Car, Roberto; Aspuru-Guzik, Alán

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Abstract: An accurate treatment of the long-range electron correlation energy, including van der Waals (vdW) or dispersion interactions, is essential for describing the structure, dynamics, and function of a wide variety of systems. Among the most accurate models for including dispersion into density functional theory (DFT) is the range-separated many-body dispersion (MBD) method [A. Ambrosetti et al., J. Chem. Phys., 2014, 140, 18A508], in which the correlation energy is modeled at short-range by a semi-local density functional and at long-range by a model system of coupled quantum harmonic oscillators. In this work, we develop analytical gradients of the MBD energy with respect to nuclear coordinates, including all implicit coordinate dependencies arising from the partitioning of the charge density into Hirshfeld effective volumes. To demonstrate the efficiency and accuracy of these MBD gradients for geometry optimizations of systems with intermolecular and intramolecular interactions, we optimized conformers of the benzene dimer and isolated small peptides with aromatic side-chains. We find excellent agreement with the wavefunction theory reference geometries of these systems (at a fraction of the computational cost) and find that MBD consistently outperforms the popular TS and D3(BJ) dispersion corrections. To demonstrate the performance of the MBD model on a larger system with supramolecular interactions, we optimized the C60@C60H28 buckyball catcher host–guest complex. In our analysis, we also find that neglecting the implicit nuclear coordinate dependence arising from the charge density partitioning, as has been done in prior numerical treatments, leads to an unacceptable error in the MBD forces, with relative errors of ∼20% (on average) that can extend well beyond 100%.
Publication Date: 27-Oct-2015
Electronic Publication Date: Jul-2016
Citation: Blood-Forsythe, Martin A., Markovich, Thomas, DiStasio, Robert A., Car, Roberto, Aspuru-Guzik, Alán. (2016). Analytical nuclear gradients for the range-separated many-body dispersion model of noncovalent interactions. Chemical Science, 7 (3), 1712 - 1728. doi:10.1039/C5SC03234B
DOI: 10.1039/C5SC03234B
ISSN: 2041-6520
EISSN: 2041-6539
Pages: 1712 - 1728
Type of Material: Journal Article
Journal/Proceeding Title: Chemical Science
Version: Final published version. This is an open access article.

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