(Experimental) You can use this variable to override the parametrization used by the DFT-D3 van deer Waals correction. Normally you need not set this variable, as the proper value will be selected by Octopus (if available).
This variable takes a string value, the valid values can be found in the source file ‘external_libs/dftd3/core.f90’. For example you can use:
VDWD3Functional = ‘pbe’