Evaluating dispersion forces for optimization of van der Waals complexes using a non-empirical functional

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1 Citation (Scopus)


Modelling dispersion interactions with traditional density functional theory (DFT) is a challenge that has been extensively addressed in the past decade. The exchange-dipole moment (XDM), among others, is a non-empirical add-on dispersion correction model in DFT. The functional PW86+PBE+XDM for exchange, correlation and dispersion, respectively, compromises an accurate functional for thermochemistry and for van der Waals (vdW) complexes at equilibrium and non-equilibrium geometries. To use this functional in optimizing vdW complexes, rather than computing single point energies, it is necessary to evaluate accurate forces. The purpose of this paper is to validate that, along the potential energy surface, the distance at which the energy is minimum is commensurate with the distance at which the forces vanish to zero. This test was validated for 10 rare gas diatomic molecules using various integration grids and different convergence criteria. It was found that the use of either convergence criterion, 10-6 or 10-8, in Gaussian09, does not affect the accuracy of computed optimal distances and binding energies. An ultrafine grid needs to be used when computing accurate energies using generalized gradient approximation functionals. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

Original languageEnglish
Article number20160145
JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2080
Publication statusPublished - Nov 13 2016
Externally publishedYes


  • Computing forces
  • Density functional theory
  • Dispersion interactions
  • Exchange-hole dipole moment model
  • Van der Waals complexes

ASJC Scopus subject areas

  • General Mathematics
  • General Engineering
  • General Physics and Astronomy


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