Do Semilocal Density-Functional Approximations Recover Dispersion Energies at Small Intermonomer Separations?

Muhammad Shahbaz and Krzysztof Szalewicz
Phys. Rev. Lett. 121, 113402 – Published 12 September 2018
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Abstract

The methods that add dispersion energies to interaction energies computed using density-functional theory (DFT), known as DFT+D methods, taper off the dispersion energies at distances near van der Waals minima and smaller based on an assumption that DFT starts to reproduce the dispersion energies there. We show that this assumption is not correct as the alleged contribution behaves unphysically and originates to a large extent from nonexchange-correlation terms. Thus, dispersion functions correct DFT in this region for deficiencies unrelated to dispersion interactions.

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  • Received 11 April 2018
  • Revised 12 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.113402

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & Optical

Authors & Affiliations

Muhammad Shahbaz* and Krzysztof Szalewicz

  • Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA

  • *shahbaz@udel.edu
  • szalewic@udel.edu

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Issue

Vol. 121, Iss. 11 — 14 September 2018

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