[Wien] convergence of Bader (aim) calculations

[Peter Blaha]

In terms of aim, there are two different meanings of "accuracy":

a) An scf charge density depends of course to some extend on RKmax, RMT,
k-points,.... and of course on the xc potential. So indirectly, your Bader
results depend on them, however,

b) for a given clmsum file the Bader charges should give you a neutral charge.
So a main problem seems the integration with aim, and this can only be
solved (maybe) with more theta/phi rays (and maybe by choosing more points
in the interstital integration).

So work on a) when your K-charge is changing too much with RKmax,...
but on b) when the integration does not sum to zero.

> ** About the 'total charge'  :
> As mentioned in my e-mail, I also calculated this 'total charge', and for the best calculations (rkmax 6.5 to 7) I have 0.35 electrons too many (roughly 0.006 per atom), so it seems the Bader surfaces are slightly overlapping.
>
> ** The accuracy required :
> The system is KC60, which means that charge from one K atom will be transferred to a molecule consisting of 60 C atoms.  So the charge transfer per atom is expected to be very small.  My current values  per C atom are comparable to the precision you mention.  An accuracy of 0.005 would be nice.



                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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