Feff8.0 reports bad counts in SCF loop

["John J. Rehr" <jjr@leonardo.phys.washington.edu>]

Dear Apurva,

  The problem is that the SCF loop has difficulty converging for
f-electron materials like La. To improve this Alex made a frozen
ground state f-elecron configuration the default in FEFF8.2.
So the quick fix for such SCF problems in f-electron materials
is simply to upgrade to FEFF8.2. Alternatively you can play with
the convergence parameter ca, e.g., ca = 0.05, but it's still
likely you will find convergence difficulties.

-----original msg from mehta@SLAC.Stanford.EDU

Hi John and Alex,

I am using feff8 to calculate polarization dependent Mn K edge XANES for
some single crystal data I collected on LaSrMnO4 on BL 9-3.  Feff is
doing a remarkable job of calculating the edge features based on the
neutron diffraction structural parameter.  However, on my last
simulation feff is stuck in an endless loop.
It calculates l-DOS for iteration number 1 OUT of 30.  It ends by

Found Bad Counts..
Occupation number in getorb is 0.000
Will repeat this iteration.

It does the iteration again, but still finds "bad counts" and repeats.
I have let it run several repeat cycles over a weekend, but it doesn't
appear to extricate itself.  I have tried various things to break it,
but without much success.  (At times it reaches iteration 16 before it
finds this bug and goes back to iteration 1 and gets stuck.) I do not
know what to do next.  Could you please help?

thanks

Apurva Mehta
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