IVDW: Difference between revisions

Revision as of 08:48, 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.

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 is to add a dispersion correction term $E_{\mathrm{disp}}$ to the conventional Kohn-Sham 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 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)

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 DFT-D2 method is now obsolete. If LVDW=.TRUE. is defined, IVDW is automatically set to 1 (unless IVDW is specified in INCAR).

@@ Line 1: / Line 1: @@
 {{TAGDEF|IVDW|0 {{!}} 1 {{!}} 10 {{!}} 11 {{!}} 12 {{!}} 2 {{!}} 20 {{!}} 21 {{!}} 202 {{!}} 4|0 (no correction)}}
-Description: {{TAG|IVDW}} specifies a vdW correction.
+Description: {{TAG|IVDW}} specifies a vdW (dispersion) correction.
 ----
-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 is to add a correction to the conventional Kohn-Sham DFT energy <math>E_{\rm tot}^{\mathrm{KS-DFT}}</math>:
+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 is to add a dispersion correction term <math>E_{\mathrm{disp}}</math> to the conventional Kohn-Sham 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>
-The correction term <math>E_{\mathrm{disp}}</math> can be computed using one of the available approximate methods listed below.
+<math>E_{\mathrm{disp}}</math> can be calculated using one of the available approximate methods listed below.
 *{{TAG|IVDW}}=0 no correction
@@ Line 19: / Line 19: @@
 *{{TAG|IVDW}}=4 {{TAG|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
+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.
-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 {{TAG|LVDW}} used in previous versions of VASP

Revision as of 08:48, 19 July 2022

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