Ian, You can turn on/off the a posteriori vdW Grimme correction for only the atoms and species that you want, but as far as I know the self-consistent vdW is applied to the entire simulation box like any other xc-functional. Other than that, I think if you're using a vdW-xc functional that gets the correct geometric and electronic structure of the bulk form of your substrate, you should be in good hands (except for the matter of increased computational time).
Cheers, *Abraham Hmiel* Katherine Belz Groves Fellow in Nanoscience Xue Group, College of Nanoscale Science and Engineering at SUNY Albany On Fri, Jul 26, 2013 at 8:16 AM, Ian Shuttleworth < [email protected]> wrote: > Siesterers > > I am using siesta-trunk-421 / 433. > > Is there any way to "turn on" van der Waals interactions for just a > specific part of the system you're looking at? > > For example, organics adsorbed on a surface : I want to investigate vdW > between the adsorbates but I dont want to use vdW for the substrate. > > The only command I can find it XC.hybrid which seems to apply to all > species. > > Thanks > > Ian Shuttleworth >
