[Wien] R0 for atom -3 Z= 33.00 too big

[Peter Blaha]

The message complains about R0 for the third atom.
"WARNING: R0 for atom -3 Z= 33.00 too big".
Thus you don't need to change RMTs, but change R0. (I admit, the additional
tip about "lower RMT or increase core-separation" is misleading).

I do NOT understand how you created your case.struct file ?

When I create your struct file from scratch using w2web I obtain the
following radial parameters:
grep R0 test.struct
Cs         NPT=  781  R0=0.00001000 RMT=    2.5000   Z: 55.0
Fe         NPT=  781  R0=0.00005000 RMT=    2.2100   Z: 26.0
As         NPT=  781  R0=0.00005000 RMT=    1.9600   Z: 33.0

While you have
Cs         NPT=  781  R0=0.00001000 RMT=    2.5000   Z: 55.0
Fe         NPT=  781  R0=0.00001000 RMT=    2.2100   Z: 26.0
As         NPT=  781  R0=0.00010000 RMT=    1.9600   Z: 33.0

With my struct file, there is no complain.

PS: If you "copy" a struct file from a similar compound and just change an atom,
(eg. P vs As) manually, you will have to change also R0 manually until lstart
does not complain anymore.

Am 12.05.2011 17:38, schrieb Jakob Kanter:
>
>
> Dear Prof. Blaha, dear Wien2K community,
>
> we are running into problems trying to calculate the Fermi surface
> of CsFe2As2.
>
> Executing "lstart 13 -6.0" results in:
> "WARNING: R0 for atom -3 Z= 33.00 too big".
> Suggesting to lower RMT or increase the core-separation energy.
>
> With the RMT values generated by StructGen we find charges outside
> the core of
>
> Cs: 9.1e-5 (out of a total core charge of 36)
> Fe: 2.0e-3 (out of 12)
> As: 2.0e-3 (out of 18)
>
> Increasing the RMT for As lowers the "charge outside sphere" to 1.6e-3 but
> does not help the warning message issue.
>
> Cranking the core-separation energy all the way down to -10 Ry changes
> the last core state orbital of As from 3P to 3P* and reduces the
> "charge outside sphere" to 5e-4 but the warning remains.
>
> I.e. changing RMT and the core separation energy over the whole parameter
> range doesn't affect the warning.
>
> Looking at the CsFe2As2.struct file file, it occurs that R0 is 10 times
> larger for As compared to Cs and Fe (0.001 vs. 0.00001) but
> lowering this value in the struct file causes nn to act up.
>
> Ignoring the warning the calculation leads to a Fermi surface which
> is obviously wrong as it is not symmetric under inversion of k.
>
> Our questions would be:
>
> 1) Should R0 be edited directly in the struct file? (probably not)
>
> 2) Is the charge leaking out of the MT really the problem? (the charges
> seemed rather small and were in fact bigger for Fe, but the warning
> occurred for As). If so, should we try to force the highest
> core states into valence states by putting an extra LO for that state?
> Are there some issues / stumbling blocks to be considered?
>
> We are running Wien2K v11.1, compiled with ifort v12.0.3
> (Intel Fortran Composer XE for Linux 2011.3-174) on a
> Intel i7-960 system.
>
> Please find the struct file attached.
>
> Thank you for your time and with best regards,
>
> Jakob Kanter
>
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 

                                       P.Blaha
--------------------------------------------------------------------------
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/
--------------------------------------------------------------------------