DFT-D4: Difference between revisions
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DFT-D4{{cite|caldeweyher:jcp:2019}}{{cite|dftd4_1}}{{cite|dftd4_2}} is an external package that can be [[Makefile.include#DFT- | 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. | ||
This is an approximation of the atom-pairwise type that depends only on the structure of the system, which allows for a fast computation. | 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. | Since every functional has different interactions between atoms, DFT-D4 tailors its adjustable parameters to the functional. | ||
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As a result, you can relax structures or run [[MD|MD simulations]] with an approximate treatment of vdW interactions. | As a result, you can relax structures or run [[MD|MD simulations]] with an approximate treatment of vdW interactions. | ||
{{NB|important| | {{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- | *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. | *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. | ||
}} | }} | ||
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{{TAG|VDW_CNRADIUS}}, | {{TAG|VDW_CNRADIUS}}, | ||
[[DFT-D3]], | [[DFT-D3]], | ||
[[simple-DFT-D3 | [[simple-DFT-D3]] | ||
[[Category:Exchange-correlation functionals]][[Category:Van der Waals functionals]][[Category:Howto]] | [[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:
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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
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