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DFT-D4 is an external package maintained by the Grimme group that can be [[Makefile.include#DFT-D4_.28optional.29|linked to VASP]].
DFT-D4{{cite|caldeweyher:jcp:2019}}{{cite|dftd4_1}}{{cite|dftd4_2}} is an external package that can be [[Makefile.include#DFT-D4 and simple-DFT-D3_.28optional.29|linked to VASP]]. DFT-D4 adds to the DFT energy expression a term that accounts for the [[:Category:Van der Waals functionals|van der Waals (vdW) interactions]], which are in principle not included in semilocal and hybrid exchange-correlation functionals.
Read the [https://dftd4.readthedocs.io/en/latest/ documentation] for more information about this package.
This is an approximation of the atom-pairwise type that depends only on the structure of the system, which allows for a fast computation.
Since every functional has different interactions between atoms, DFT-D4 tailors its adjustable parameters to the functional.
For more information regarding these parameters, please refer to the DFT-D4 paper{{cite|caldeweyher:jcp:2019}} and websites.{{cite|dftd4_1}}{{cite|dftd4_2}}


== Usage ==
== Usage ==


In general, VASP passes the used exchange-correlation functional to DFT-D4.
For some of the common exchange-correlation functionals (e.g., PBE, SCAN, or HSE06) it is sufficient to set {{TAG|IVDW}}=13 in the {{FILE|INCAR}} file. Internally, VASP passes automatically the name of the functional to DFT-D4. However, for other functionals the {{TAG|DFTD4_XC}} tag has to be used to specify the functional to DFT-D4 (the names are listed in the file param.f90 of the DFT-D4 source code).
DFT-D4 decides on the optimal choice of parameters for the specific functional.
Subsequently, DFT-D4 maps the functional name to optimized settings for the adjustable parameters of the vdW interaction.
Typically, you do not need to modify the parameters of the interaction.
VASP uses these parameters to compute the DFT-D4 energies, forces, and stresses in every ionic step and adds them to the corresponding DFT terms.
If you want to or if DFT-D4 does not implement specific parameters for the functional,
As a result, you can relax structures or run [[MD|MD simulations]] with an approximate treatment of vdW interactions.
set the following parameters in the {{FILE|INCAR}} file:
{{NB|important|
*The API of DFT-D4 has been modified starting with version 4.0.0. The adaptation has been made in VASP.6.6.0. Versions of DFT-D4 with the old API (v3.7.0 and older) can still be compiled with VASP.6.6.0 as explained [[Makefile.include#DFT-D4 and simple-DFT-D3_.28optional.29|here]].
*Below, we explain how to tweak the parameters of DFT-D4. Typically, you should not modify them unless you have a very good reason, e.g., because the interface is not implemented for the exchange-correlation functional you use.
}}


* {{TAG|VDW_S6}}, {{TAG|VDW_S8}} determine the strength of the dipole-dipole and dipole-quadrupole interaction.
VASP allows setting the following tags in the {{FILE|INCAR}} file:
* {{TAG|VDW_A1}}, {{TAG|VDW_A2}} are scaling constants in the Becke-Johnson damping.
* {{TAG|DFTD4_MODEL}} : dispersion model (available from VASP.6.6.0 onwards).
 
* {{TAG|DFTD4_XC}} : functional name to determine the set of vdW parameters (available from VASP.6.6.0 onwards).
For more information regarding these parameters, please refer to the DFT-D4 paper.{{cite|caldeweyher:pccp:2020}}
* {{TAG|VDW_S6}} : scaling of the dipole-dipole dispersion.
* {{TAG|VDW_S8}} : scaling of the dipole-quadrupole dispersion.
* {{TAG|VDW_A1}} : scaling of the critical radii in the Becke-Johnson rational damping.
* {{TAG|VDW_A2}} : offset of the critical radii in the Becke-Johnson rational damping.
* {{TAG|VDW_S9}} : scaling of the three-body dispersion energy (available from VASP.6.6.0 onwards).
* {{TAG|VDW_RADIUS}} : two-body interaction cutoff (available from VASP.6.6.0 onwards).
* {{TAG|VDW_CNRADIUS}} : coordination number cutoff (available from VASP.6.6.0 onwards).


== References ==
== References ==
Line 19: Line 30:


== Related tags and articles ==
== Related tags and articles ==
{{TAG|IVDW}},
{{TAG|DFTD4_MODEL}},
{{TAG|DFTD4_XC}},
{{TAG|VDW_S6}},
{{TAG|VDW_S6}},
{{TAG|VDW_S8}},
{{TAG|VDW_S8}},
{{TAG|VDW_A1}},
{{TAG|VDW_A1}},
{{TAG|VDW_A2}},
{{TAG|VDW_A2}},
{{TAG|VDW_S9}},
{{TAG|VDW_RADIUS}},
{{TAG|VDW_CNRADIUS}},
[[DFT-D3]],
[[DFT-D3]],
[[Makefile.include#DFT-D4_.28optional.29|Linking to DFT-D4]]
[[simple-DFT-D3]]


[[Category:Exchange-correlation functionals]][[Category:Van der Waals functionals]]
[[Category:Exchange-correlation functionals]][[Category:Van der Waals functionals]][[Category:Howto]]

Latest revision as of 16:40, 5 March 2026

DFT-D4[1][2][3] is an external package that can be linked to VASP. DFT-D4 adds to the DFT energy expression a term that accounts for the van der Waals (vdW) interactions, which are in principle not included in semilocal and hybrid exchange-correlation functionals. This is an approximation of the atom-pairwise type that depends only on the structure of the system, which allows for a fast computation. Since every functional has different interactions between atoms, DFT-D4 tailors its adjustable parameters to the functional. For more information regarding these parameters, please refer to the DFT-D4 paper[1] and websites.[2][3]

Usage

For some of the common exchange-correlation functionals (e.g., PBE, SCAN, or HSE06) it is sufficient to set IVDW=13 in the INCAR file. Internally, VASP passes automatically the name of the functional to DFT-D4. However, for other functionals the DFTD4_XC tag has to be used to specify the functional to DFT-D4 (the names are listed in the file param.f90 of the DFT-D4 source code). Subsequently, DFT-D4 maps the functional name to optimized settings for the adjustable parameters of the vdW interaction. VASP uses these parameters to compute the DFT-D4 energies, forces, and stresses in every ionic step and adds them to the corresponding DFT terms. As a result, you can relax structures or run MD simulations with an approximate treatment of vdW interactions.

Important:
  • The API of DFT-D4 has been modified starting with version 4.0.0. The adaptation has been made in VASP.6.6.0. Versions of DFT-D4 with the old API (v3.7.0 and older) can still be compiled with VASP.6.6.0 as explained here.
  • Below, we explain how to tweak the parameters of DFT-D4. Typically, you should not modify them unless you have a very good reason, e.g., because the interface is not implemented for the exchange-correlation functional you use.

VASP allows setting the following tags in the INCAR file:

  • DFTD4_MODEL : dispersion model (available from VASP.6.6.0 onwards).
  • DFTD4_XC : functional name to determine the set of vdW parameters (available from VASP.6.6.0 onwards).
  • VDW_S6 : scaling of the dipole-dipole dispersion.
  • VDW_S8 : scaling of the dipole-quadrupole dispersion.
  • VDW_A1 : scaling of the critical radii in the Becke-Johnson rational damping.
  • VDW_A2 : offset of the critical radii in the Becke-Johnson rational damping.
  • VDW_S9 : scaling of the three-body dispersion energy (available from VASP.6.6.0 onwards).
  • VDW_RADIUS : two-body interaction cutoff (available from VASP.6.6.0 onwards).
  • VDW_CNRADIUS : coordination number cutoff (available from VASP.6.6.0 onwards).

References

  1. ↑ a b E. Caldeweyher, S. Ehlert, A. Hansen, H. Neugebauer, S. Spicher, C. Bannwarth, and S. Grimme, J. Chem. Phys. 150, 154122 (2019).
  2. ↑ a b https://dftd4.readthedocs.io
  3. ↑ a b https://github.com/dftd4

Related tags and articles

IVDW, DFTD4_MODEL, DFTD4_XC, VDW_S6, VDW_S8, VDW_A1, VDW_A2, VDW_S9, VDW_RADIUS, VDW_CNRADIUS, DFT-D3, simple-DFT-D3

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