IVDW: Difference between revisions
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Kohn-Sham DFT energy <math>E_{\mathrm{KS-DFT}}</math>: | Kohn-Sham DFT energy <math>E_{\mathrm{KS-DFT}}</math>: | ||
<math> E_{\mathrm{DFT-disp}} = E_{\mathrm{KS-DFT}} + E_{\mathrm{disp}}.</math> | :<math> E_{\mathrm{DFT-disp}} = E_{\mathrm{KS-DFT}} + E_{\mathrm{disp}}.</math> | ||
The correction term <math>E_{\mathrm{disp}}</math> is computed using some of the available approximate methods. | The correction term <math>E_{\mathrm{disp}}</math> is computed using some of the available approximate methods. | ||
Revision as of 07:35, 8 April 2022
IVDW = 0 | 1 | 10 | 11 | 12 | 2 | 20 | 21 | 202 | 4
Default: IVDW = 0
Description: This tag controls whether vdW corrections are calculated or not. If they are calculated IVDW controls how they are calculated.
Popular local and semilocal density functionals are unable to describe correctly van der Waals interactions resulting from dynamical correlations between fluctuating charge distributions. A pragmatic method to work around this problem is to add a correction to the conventional Kohn-Sham DFT energy :
The correction term is computed using some of the available approximate methods. The choice of vdW method is controlled via the following tags:
- IVDW=0 no correction
- IVDW=1|10 DFT-D2 method of Grimme (available as of VASP.5.2.11)
- IVDW=11 zero damping DFT-D3 method of Grimme (available as of VASP.5.3.4)
- IVDW=12 DFT-D3 method with Becke-Jonson damping (available as of VASP.5.3.4)
- IVDW=13 DFT-D4 method (available as of VASP.6.2 as external package).
- IVDW=2|20 Tkatchenko-Scheffler method (available as of VASP.5.3.3)
- IVDW=21 Tkatchenko-Scheffler method with iterative Hirshfeld partitioning (available as of VASP.5.3.5)
- IVDW=202 Many-body dispersion energy method (MBD@rSC) (available as of VASP.5.4.1)
- IVDW=4 dDsC dispersion correction method (available as of VASP.5.4.1)
All methods listed above add vdW correction to potential energy, interatomic forces, as well as stress tensor and hence simulations such as atomic and lattice relaxations, molecular dynamics, and vibrational analysis (via finite differences) can be performed. Note, however, that these correction schemes are currently not available for calculations based on density functional perturbation theory.
N.B.: The parameter LVDW used in previous versions of VASP (5.2.11 and later) to activate DFT-D2 method is now obsolete. If LVDW=.TRUE. is defined, IVDW is automatically set to 1 (unless IVDW is specified in INCAR).
Related Tags and Sections
LVDW, DFT-D2, DFT-D3, Tkatchenko-Scheffler method, Tkatchenko-Scheffler method with iterative Hirshfeld partitioning, Many-body dispersion energy, dDsC dispersion correction
see also the alternative vdW-DF functionals: LUSE_VDW, VdW-DF functional of Langreth and Lundqvist et al.