DFT-D4
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.
Usage
In general, VASP passes the used exchange-correlation functional to DFT-D4. DFT-D4 decides on the optimal choice of parameters for the specific functional. Typically, you do not need to modify the parameters of the interaction. If you want to or if DFT-D4 does not implement specific parameters for the functional, set the following parameters in the INCAR file:
- 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]