DFT-D4: Difference between revisions

Revision as of 20:05, 13 June 2024

DFT-D4 is an external package maintained by the Grimme group that can be linked to VASP. Read the documentation for more information about this package. DFT-D4 adds van-der-Waals (vdW) interactions to DFT because they are not included in most exchange-correlation functionals. It approximates the vdW interactions considering only 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.

Usage

In most cases, it is sufficient to set IVDW=13 in the INCAR file if VASP was compiled and linked to DFT-D4. Internally, VASP passes the name of the used exchange-correlation functional to DFT-D4. Based on this, DFT-D4 internally maps the name of functionals to optimized settings for the adjustable parameters. 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.

Warning: 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 to change the strength of the vdW interaction.

VDW_S6, VDW_S8 determine the strength of the dipole-dipole and dipole-quadrupole interaction.
VDW_A1, VDW_A2 are scaling constants in the Becke-Johnson damping.

For more information regarding these parameters, please refer to the DFT-D4 paper.^[1]

References

↑ E. Caldeweyher, J.-M. Mewes, S. Ehlert, and S. Grimme, Extension and evaluation of the D4 London-dispersion model for periodic systems, Phys. Chem. Chem. Phys. 22, 8499 (2020).

@@ Line 1: / Line 1: @@
 DFT-D4 is an external package maintained by the Grimme group that can be [[Makefile.include#DFT-D4_.28optional.29|linked to VASP]].
 Read the [https://dftd4.readthedocs.io/en/latest/ documentation] for more information about this package.
+DFT-D4 adds van-der-Waals (vdW) interactions to DFT because they are not included in most exchange-correlation functionals.
+It approximates the vdW interactions considering only 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.
 == Usage ==
-In general, VASP passes the used exchange-correlation functional to DFT-D4.
+In most cases, it is sufficient to set {{TAG|IVDW}}=13 in the {{FILE|INCAR}} file if VASP was compiled and linked to DFT-D4.
-DFT-D4 decides on the optimal choice of parameters for the specific functional.
+Internally, VASP passes the name of the used exchange-correlation functional to DFT-D4.
-Typically, you do not need to modify the parameters of the interaction.
+Based on this, DFT-D4 internally maps the name of functionals to optimized settings for the adjustable parameters.
-If you want to or if DFT-D4 does not implement specific parameters for the functional,
+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.
-set the following parameters in the {{FILE|INCAR}} file:
+As a result, you can relax structures or run MD simulations with an approximate treatment of vdW interactions.
+{{NB|warning|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 {{FILE|INCAR}} file to change the strength of the vdW interaction.
 * {{TAG|VDW_S6}}, {{TAG|VDW_S8}} determine the strength of the dipole-dipole and dipole-quadrupole interaction.
@@ Line 19: / Line 25: @@
 == Related tags and articles ==
+{{TAG|IVDW}},
 {{TAG|VDW_S6}},
 {{TAG|VDW_S8}},