[gpaw-users] Ghost atoms in fd mode?

[Kristen Kaasbjerg]

Hi again

>>2012/7/8 Kristen Kaasbjerg <kkaa at fysik.dtu.dk>:
>> Hi GPAW'ers,
>>
>> I am interested in calculating the difference in the PAW Hamiltonian including projector
>> terms etc between two calculations differing by one removed atom in one of them. That
>> would be relatively straight forward if I could replace the atom I would like to remove
>> with a ghost atoms, however, since I am using fd mode that does not seem to be possible.
>>
>> Is the correct and in case yes, any suggestions for how to do this in a simple way?
>>
>> Thanks
>> Kristen
>
>Do you get an error when you try to specify a ghost atom?  It doesn't
>seem to me that there should be any fundamental problem with this.

As far as I could tell from the wiki the ghost option is only mentioned in the context of
LCAO calcuation so I haven't tried it yet. But if you are telling me that chances are that
it should work, I will give it a shot.

>(A ghost atom does not contribute to the Hamiltonian except if you
>represent it in an atomic basis set.  Therefore I do not quite
>understand what the purpose of this substitution is.  Do you just want
>the Atoms objects to have the same number of atoms?)

Since I am going to substract the full PAW hamiltonians from two calculations differing
by one removed atom, my experience so far with the projector terms which have sums
over atoms tells me that this will be straight forward if both Atoms objects contain the
same atoms and associated setups. So this leads me to my next questions: do ghost 
atoms have the same projectors etc as the elements of the ghost atoms otherwise would
have had?

Kristen


>Regards
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