IVDW: Difference between revisions

Revision as of 09:32, 19 July 2022

IVDW = 0 | 1 | 10 | 11 | 12 | 2 | 20 | 21 | 202 | 4
Default: IVDW = 0 (no correction)

Description: IVDW specifies a vdW (dispersion) correction.

For fundamental reasons, the semilocal and hybrid exchange-correlation functionals are unable to describe properly vdW interactions resulting from dynamical correlations between fluctuating charge distributions (called London dispersion forces). An approximate way to work around this problem and to get more reliable results for vdW systems is to add a dispersion correction term, $E_{\mathrm{disp}}$ , to the conventional KS-DFT energy $E_{\rm tot}^{\mathrm{KS-DFT}}$ :

E_{\rm tot}^{\mathrm{KS-DFT-disp}} = E_{\rm tot}^{\mathrm{KS-DFT}} + E_{\mathrm{disp}}.

$E_{\mathrm{disp}}$ can be calculated using one of the available approximate methods listed below.

IVDW=0 : no dispersion correction (default)
IVDW=1|10 : DFT-D2 method of Grimme (available as of VASP.5.2.11)
IVDW=11 : DFT-D3 method of Grimme with zero-damping function (available as of VASP.5.3.4)
IVDW=12 : DFT-D3 method with Becke-Johnson damping function (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)

With all methods listed above, a dispersion correction is added to the total energy, potential, interatomic forces and stress tensor, such that 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 the DFT-D2 method is now obsolete. If LVDW=.TRUE. is defined, IVDW is automatically set to 1 (unless IVDW is specified in INCAR).

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 Description: {{TAG|IVDW}} specifies a vdW (dispersion) correction.
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-For fundamental reasons, the semilocal and hybrid exchange-correlation functionals are unable to describe properly vdW interactions resulting from dynamical correlations between fluctuating charge distributions (called London dispersion forces). A pragmatic way to work around this problem and to get more reliable results for vdW systems is to add a dispersion correction term, <math>E_{\mathrm{disp}}</math>, to the conventional KS-DFT energy <math>E_{\rm tot}^{\mathrm{KS-DFT}}</math>:
+For fundamental reasons, the semilocal and hybrid exchange-correlation functionals are unable to describe properly vdW interactions resulting from dynamical correlations between fluctuating charge distributions (called London dispersion forces). An approximate way to work around this problem and to get more reliable results for vdW systems is to add a dispersion correction term, <math>E_{\mathrm{disp}}</math>, to the conventional KS-DFT energy <math>E_{\rm tot}^{\mathrm{KS-DFT}}</math>:
 :<math> E_{\rm tot}^{\mathrm{KS-DFT-disp}} = E_{\rm tot}^{\mathrm{KS-DFT}} + E_{\mathrm{disp}}.</math>

Revision as of 09:32, 19 July 2022

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