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Empirical Dispersion Correction for DFT Calculations

Based on an idea that has earlier been proposed for Hartree-Fock calculations[75,76], a general empirical dispersion correction has been proposed by Stefan Grimme for density functional calculations [77]. A modified version of the approach with extension to more elements and more functionals has been published in ref. [78]. The most recent implementation [79] is less empirical, i.e. the most important parameters are computed by first principles, and it provides a consistent description across the whole periodic system.

The first version (DFT-D1) can be invoked by the keyword $olddisp in the control file. The second version (DFT-D2) is used if the keyword $disp is found. For the usage of DFT-D3 just add keyword $disp3 to the control file. Only one of the three keywords is expected to be present.


If DFT-D3 is used, the total energy is given by

EDFT-D3 = EKS-DFT - Edisp (6.9)

where EKS-DFT is the usual self-consistent Kohn-Sham energy as obtained from the chosen functional and Edisp is a dispersion correction given by the sum of two- and three-body energies

Edisp = E(2) + E(3), (6.10)

with the dominating two-body term

E(2) = $\displaystyle \sum_{{AB}}^{}$$\displaystyle \sum_{{n=6,8,10,...}}^{}$sn$\displaystyle {\frac{{C_n^{AB}}}{{r_{AB}^n}}}$fd, n(rAB). (6.11)

The first sum runs over all atom pair, CnAB denotes the nth-order dispersion coefficient for atom pair AB, rAB is their interatomic distance, and fd, n is a damping function.


Please have look at http://toc.uni-muenster.de/DFTD3 for more detailed information.


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Next: Hartree-Fock and DFT Response Up: Hartree-Fock and DFT Calculations Previous: Calculation Setup   Contents   Index
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