[Wien] consistent RKmax and sphere size settings

[Pavel Ondračka]

Dear Wien2k mailing list,

I have a series of TiN and TiON amorphous-like structures where I have
some large differences in spheres sizes for N atoms. In most of the
structures the smallest N sphere is around 1.6-1.7, however in some I
have few N atoms with 1.3 (the structures should be OK, this much
smaller size is due to some rare local configuration which would
correspond to something like N split interstitial in crystalline
structure).

My goal is to calculate core electron binding energies of N1s levels of
many atoms in the structures (at least 200 core-hole calculations) and
I need to be consistent over different structures in the series.

So usually I would just check what is the smallest N sphere size in the
whole set, and force it for all N atoms in all structures and than use
the identical RKmax for all structures, just to be sure I'm consistent.
This is unfortunatelly not very efficient with respect to the
calculation speed as I have quite large cells (around 150 atoms). Is
there another way how can I save some CPU time and keep the
consistency?

I was for example thinking if I can force somehow two different N
sphere sizes (one for the N split intestitial, which I have usually
just one in the whole cell and one larger for the rest of N atoms),
than I would have consistent sphere size for the rest of N atoms in the
series and I could change the RKmax to keep the same largest K-vector
which should be enough to guarantee consistency for all N atoms expect
the split interstitials (but I don't care that much about them).
However as far as I understand this is not possible?

Any ideas would be appreciated.

Best regards
Pavel Ondracka