[Wien] question about tetra's choice of Emax
Peter Blaha
pblaha at theochem.tuwien.ac.at
Wed Nov 16 16:06:26 CET 2016
The question is: what does your scf2up/dn files (and the scf1up/dn files
say ?
In case.in1 there should be an EMAX of 1.5 ?
and in scf1up/dn there should be eigenvalues up to 1.5+EF ??
and in scf2up/dn there is a list of "bandranges". Are there "empty" band
ranges (band which have zero occupation) ??
Of course it could simply be that you have so steep bands that one does
not catch an empty band within 1.5+EF Ry. In this case one has to
increase EMAX in case.in1. And yes, if this really happens, one should
give a :WAR ...(and I don't think this is there yet ..., but I would
need a case where this happens).
Regards
On 11/16/2016 12:25 PM, pieper wrote:
> Thanks for the quick response!
>
> Sorry, I did not fully catch the problem of consistency between what is
> calculated in lapw1 and integrated in tetra.
>
> However, your PS and PPS leave me worried about where things go sideways
> with something as simple as fcc Co should be.
>
> As for the version, my VERSION file says
> WIEN2k_14.2 (Release 15/10/2014)
> which to my knowledge is not too bad? It does not include the dynamical
> Emax in lapw1?
>
> With that version, kgen 10000 vectors, spin-resolved, and everything
> else default in w2web, I get from tetra something like the file below.
> Emax is apparently changed to a value below E_F.
>
> I understand that this might lead to problems already in the scf because
> the wrong states are occupied, but in that case again I cannot rely on
> the DOS, even when I increase Emax in .in1 and run lapw1 ... I have to
> re-run the scf, correct?
>
>
> ----- Co-fcc.outputtup ------
> Co-fcc #
>
> IAV : 0
> NPRINT : 1
> 2 CASES FOR DOS : ATOM L
>
> cc-Co
> LATTICE CONST.= 6.79300 6.79300 6.79300 FERMI ENERGY= 0.56702
> 48 <; NMAT <; 63 SPIN=2 NATO= 2
> JATOM 1 MULT= 1 ISPLIT= 2 tot,0,1,2,D-eg,D-t2g,3
> CASE 1 : ATOM NUMBER 0 COLUMN READ 0 DOSTYPE=total-DOS
> CASE 2 : ATOM NUMBER 1 COLUMN READ 1 DOSTYPE= 1:total
> We will add 0 DOS-cases together:
> BAND LIMITS OF BAND 1 ARE -3.81359 -3.79544
> BAND LIMITS OF BAND 2 ARE -3.80710 -3.79544
> BAND LIMITS OF BAND 3 ARE -3.80235 -3.79544
> BAND LIMITS OF BAND 4 ARE -0.07833 0.28402
> BAND LIMITS OF BAND 5 ARE 0.24033 0.37076
> BAND LIMITS OF BAND 6 ARE 0.32045 0.48759
> BAND LIMITS OF BAND 7 ARE 0.37076 0.51438
> BAND LIMITS OF BAND 8 ARE 0.40511 0.51502
> BAND LIMITS OF BAND 9 ARE 0.43442 1.04422
> EMAX reduced due to lower HIGHEST BAND-minimum
> EMIN, DE, EMAX : -0.50000 0.00200 0.43442
>
> EMIN= -0.50000 EMAX= 0.43442 EFACTR= 499.99996948 ESTEP = 0.00200
> ENERGY BAND 1 THROUGH 9 ENERGY CHANNEL: 1 TO 468
> NUMBER OF K-POINTS: 165
> NUMBER OF TETRAHEDRONS: 693
> # BAND 9
> #EF= 0.56702 NDOS= 2 NENRG= 468 Gaussian bradening: 0.00300
> NUMBER OF ELECTRONS UP TO EF : 0.0000
>
> DOS in states/Ry/spin
> smearing 1 0.398942274850643 2.00000000000000
> smearing 1 0.398942274850643 2.00000000000000
> # ENERGY 0 total-DOS 1 1:total
> -0.50000 0.00 0.0000 0.00 0.0000
> -0.49800 0.00 0.0000 0.00 0.0000
> -0.49600 0.00 0.0000 0.00 0.0000
> .
> .
> .
> ------------------------------------------------------------------
>
>
>
> ---
> Dr. Martin Pieper
> Karl-Franzens University
> Institute of Physics
> Universitätsplatz 5
> A-8010 Graz
> Austria
> Tel.: +43-(0)316-380-8564
>
>
> Am 16.11.2016 07:41, schrieb Peter Blaha:
>> The DOS is calculated up to a value for which we can guarantee that
>> the DOS is correct and complete.
>>
>> Of course, the DOS up to the highest band-maximum would be non-zero,
>> but there is a chance that some (maybe a lot) of DOS is missing and a
>> user would not notice this and "misintewrprete" this wrong DOS.
>>
>> Now he can trust that the calculated DOS is ok, and if he needs higher
>> DOS, he has to increase the emax in case.in1 and/or in case.int.
>>
>> PS: You are probably using an older WIEN2k version, because now we use
>> a "dynamical" Emax in case.in1, which takes the actual EF into
>> account. But of course in cases of very steep bands above EF, the
>> default in1 file may still be insufficient.
>>
>> PPS: In your situation it could even be, that the scf calculation is
>> "wrong", since you occupied the wrong bands ....
>>
>> Am 15.11.2016 um 19:12 schrieb pieper:
>>> Hello, mailing list,
>>>
>>> yesterday I had for the first time some dispute with the way tetra
>>> automatically chooses its input energy range. I would like to understand
>>> why the particular automatic choice of Emax was introduced.
>>>
>>> Until then it worked so well that I didn't even notice that Emax is
>>> automatically adjusted, but then I wanted to illustrate Wien2k by
>>> calculating the example fcc Ni. I took Co instead of Ni, lattice
>>> constant adjusted to 6.637, RMT to touching spheres. I used w2web for
>>> initialiazation and initiating scf, kgen with 10000 vectors,
>>> spin-polarized in an FM starting configuration, no spin-orbit coupling.
>>>
>>> Then I chose DOS from the Tasks menu, skipped the optional steps lapw1
>>> and qtl, used lapw2 -qtl, configured .int to calculate just the total
>>> DOS (the default). When I proudly presented the result of dosplot to a
>>> visitor the plot ended below the Fermi energy ...
>>>
>>> Increasing Emax in .int did nothing, as the experts probably could have
>>> told me beforehand. The (in this case in my view annoying) automatic
>>> choice of Emax that kicks in is indicated in the header of .outputtup
>>> (as well as in the user guide - and yes, I know one should read it):
>>>
>>> .
>>> .
>>> .
>>> BAND LIMITS OF BAND 8 ARE 0.40511 0.51502
>>> BAND LIMITS OF BAND 9 ARE 0.43442 1.04422
>>> EMAX reduced due to lower HIGHEST BAND-minimum
>>> EMIN, DE, EMAX : -0.50000 0.00200 0.43442
>>>
>>> The problem in this case is that the 'lower highest Band-minimum' is
>>> BELOW the Fermi-energy:
>>>
>>> ******** EF and DOS at fermi level *******
>>> 0.56702 0.00 0.00
>>>
>>> So one MUST go back to the (in principle optional) lapw1 step with some
>>> larger Emax in .in1 (as indicated in the DOS menu and in the UG).
>>> Increasing Emax there appears to me a little clumsy since one has to
>>> guess an Emax that will generate a band with a band minimum above E_F.
>>>
>>> Why not have tetra choose Emax as the minimum of the Emax input in .int
>>> and the highest Band-MAXIMUM?
>>>
>>>
>>> ---
>>> Dr. Martin Pieper
>>> Karl-Franzens University
>>> Institute of Physics
>>> Universitätsplatz 5
>>> A-8010 Graz
>>> Austria
>>> Tel.: +43-(0)316-380-8564
>>>
>>>
>>> _______________________________________________
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--
P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
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