>>>> What is DZP-DZP for Fe (...) ????
Double zeta plus polarization for both 3d and 4s.
The polarization orbital (only one) is applied atop of other orbitals in
the basis, i.e. you cannot have P for both s and d. That's why DZP-DZP
sounds weird.
other complicated things. How to take into account the deformation
caused by the presence of carbon? Not only local deformation, but also
the change in the cell shape?
Well, this has nothing to do with BSSE. Normally you should compare
relaxed systems, not the same geometries.
With a non-complete basis you may have an error in final geometry, e.g.
when you study the relaxation of the molecule on the surface, the
overlap of basis functions changes, and ghosta wouldn't help here. But
this error should be small.
In case of ghosts, you can always relax the system in the presence of
ghost orbital (usually fixing it). But again the effect of the ghost on
the geometry is likely to be small, although the total energy would
change significantly.
Of course, I know you cannot apply the correction only when it interests
you...
That's the point. You can always try to use a more complete basis from
the very beginning (TZP) hoping that BSSE would be smaller. But in my
experience, TZP reduces significantly the total energy, but the BSSE
value remains comparable to DZP.
