[Wien] two different GAP value in a scf-iteration
Peter Blaha
pblaha at theochem.tuwien.ac.at
Fri Oct 5 07:22:55 CEST 2012
The gaps printed for a spin-polarized case could be wrong (in previous WIEN2k versions).
I think it has been fixed in version 12.1
In any case:
use the band-limits as you have done below for a first estimate, but:
you have only 3 k-points, so you might not have a proper k-mesh. Check the gap with a
good bandstructure calculation (in many directions in k-space) and determine at which
k-points you have the real CMB and VBM ....
Am 05.10.2012 04:37, schrieb hiroshi.nakano at sharp.co.jp:
> Dear Dr. Khuong P. Ong and all
>
> Thank you for your quick and helpful reply.
> I understand the two :GAP value mean spin-up and -dn bandgap separately.
> But I still have more focused questions.
>
> As shown in the following in the last iterations of a case.scf file,
> I understand the gap between VBM(Valence band maximum) and CBM(conduction band minimum)
> is the :GAP value. in the "spin-up" state
> 0.658001(CBM)-0.628662(VBM)=0.0293 Ry = :GAP value
>
> But in the "spin-dn" state,
> 0.661240(CBM)-0.321483(VBM)=0.3399 Ry not equals to :GAP value(-0.0057Ry)
> 0.3399 Ry is the experimentally-reasonable value for spin-dn bandgap.
> However, the :GAP value in spin-dn state has a completely different value.
>
> Do you think this results still has no bandgap?
> Do you know how to avoid this situation?
>
> Best regards
> Hiroshi Nakano
>
> ---------------------------------------------------------------
> spin-up
> ---------------------------------------------------------------
> :KPT : NUMBER OF K-POINTS: 3
> :GMA : POTENTIAL AND CHARGE CUT-OFF 12.00 Ry**.5
> Insulator, EF-inconsistency corrected
> :GAP : 0.0293 Ry = 0.399 eV (provided you have a proper k-mesh)
> Bandranges (emin - emax) and occupancy:
> :BAN00396: 396 0.304134 0.316548 1.00000000
> :BAN00397: 397 0.305358 0.316548 1.00000000
> :BAN00398: 398 0.305358 0.317255 1.00000000
> :BAN00399: 399 0.307644 0.321738 1.00000000
> :BAN00400: 400 0.615416 0.615542 1.00000000
> :BAN00401: 401 0.616532 0.616847 1.00000000
> :BAN00402: 402 0.616532 0.616847 1.00000000
> :BAN00403: 403 0.622033 0.622068 1.00000000
> :BAN00404: 404 0.622033 0.622068 1.00000000
> :BAN00405: 405 0.625018 0.625049 1.00000000
> :BAN00406: 406 0.627839 0.628662 1.00000000 ******VBM
> :BAN00407: 407 0.658001 0.746349 0.00000000 ******CBM
> :BAN00408: 408 0.718811 0.753587 0.00000000
> :BAN00409: 409 0.733103 0.768052 0.00000000
> :BAN00410: 410 0.733103 0.768052 0.00000000
> :BAN00411: 411 0.763892 0.778137 0.00000000
> Energy to separate low and high energystates: -0.35493
>
>
> :NOE : NUMBER OF ELECTRONS = 805.000
>
> :FER : F E R M I - ENERGY(TETRAH.M.)= 0.62866
>
> -------------------------------------------------------------------------
> spin-dn
> -------------------------------------------------------------------------
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> Bandranges (emin - emax) and occupancy:
> :BAN00396: 396 0.304540 0.317033 1.00000000
> :BAN00397: 397 0.305985 0.317033 1.00000000
> :BAN00398: 398 0.305985 0.317662 1.00000000
> :BAN00399: 399 0.307015 0.321483 1.00000000 *******VBM
> :BAN00400: 400 0.661240 0.754718 0.00000000 *******CBM
> :BAN00401: 401 0.732731 0.767627 0.00000000
> :BAN00402: 402 0.732731 0.767627 0.00000000
> :BAN00403: 403 0.735577 0.774775 0.00000000
> :BAN00404: 404 0.765871 0.779708 0.00000000
> :BAN00405: 405 0.765871 0.779804 0.00000000
> :BAN00406: 406 0.772715 0.779804 0.00000000
> :BAN00407: 407 0.774136 0.779967 0.00000000
> :BAN00408: 408 0.774136 0.783997 0.00000000
> :BAN00409: 409 0.774739 0.784892 0.00000000
> :BAN00410: 410 0.774739 0.788865 0.00000000
> :BAN00411: 411 0.776820 0.792280 0.00000000
> Energy to separate low and high energystates: -0.35383
>
>
> :NOE : NUMBER OF ELECTRONS = 805.000
>
> :FER : F E R M I - ENERGY(TETRAH.M.)= 0.62908
> -------------------------------------------------------------------------
>
>
>
> -----Original Message-----
> From: wien-bounces at zeus.theochem.tuwien.ac.at [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Ong Phuong Khuong (IHPC)
> Sent: Friday, October 05, 2012 10:36 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] two different GAP value in a scf-iteration
>
> I believe that there is no gap in your case. It is just simply one (GAP) for spin up and one (no GAP) for spin down.
>
> =======================================================
>
> Dr. Khuong P. Ong
>
> Research Scientist
>
> Optics and Transport (Team Leader)
>
> Materials Science & Engineering Department
>
> Institute of High Performance Computing
>
> 1 Fusionopolis Way, #16-16, Connexis, Singapore 138632
>
> Mob: +65. 81885057
> Tel(Off): +65. 64191566
> Fax: +65. 64632536
>
> =======================================================
>
>
>
> -----Original Message-----
> From: wien-bounces at zeus.theochem.tuwien.ac.at [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of hiroshi.nakano at sharp.co.jp
> Sent: Friday, October 05, 2012 9:32 AM
> To: wien at zeus.theochem.tuwien.ac.at
> Subject: [Wien] two different GAP value in a scf-iteration
>
> Dear Prof Blaha and wien2k users,
>
> I have a problem in understanding case.scf files due to two different :GAP values in each SCF iteration.
>
> I am trying to calculate electron states in Europium doped oxides and sulfides using the supercell method and spin-polarized GGA(+U) functional.
> SCF calculation and geometry optimization converge and reproduce the experimentally appropriate magnetic moments successfully.
>
> But I found all of the compounds has two bandgap parameters in a SCF-iteration including the converged last iteration.
>
> The case.scf file has two :GAP values and one :ENE value in each SCF-iterations.
> Moreover, using DFT+U or increasing k-points don't change the situation.
>
> The questions are:
> (1)Should I believe the positive bandgap value which is reasonable for the experimental results?
> (2)What do the negative :GAP values mean?
> (3)What is the recommendation to solve this problem if I should?
>
> Please tell me if you need more information to find the way to get through.
>
> -------------------------------------------------------------
> The results of the analysis of case.scf file:
> grep :ENE basioneu03.scf:
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70594742
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70642208
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70633306
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70631446
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70627735
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70622835
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70620029
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70623923
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70624546
> :ENE : ********** TOTAL ENERGY IN Ry = -222804.70625225
>
> grep :GAP case.scf:
> :GAP : 0.0293 Ry = 0.399 eV (provided you have a proper k-mesh)
> :GAP : -0.0059 Ry = -0.080 eV (provided you have a proper k-mesh)
> :GAP : 0.0293 Ry = 0.398 eV (provided you have a proper k-mesh)
> :GAP : -0.0058 Ry = -0.079 eV (provided you have a proper k-mesh)
> :GAP : 0.0289 Ry = 0.394 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> :GAP : 0.0287 Ry = 0.390 eV (provided you have a proper k-mesh)
> :GAP : -0.0056 Ry = -0.076 eV (provided you have a proper k-mesh)
> :GAP : 0.0288 Ry = 0.392 eV (provided you have a proper k-mesh)
> :GAP : -0.0056 Ry = -0.076 eV (provided you have a proper k-mesh)
> :GAP : 0.0291 Ry = 0.396 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> :GAP : 0.0292 Ry = 0.397 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> :GAP : 0.0292 Ry = 0.397 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> :GAP : 0.0291 Ry = 0.396 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> :GAP : 0.0291 Ry = 0.396 eV (provided you have a proper k-mesh)
> :GAP : -0.0057 Ry = -0.077 eV (provided you have a proper k-mesh)
> ---------------------------------------------------------------------------
>
> Regards,
> Hiroshi Nakano
>
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--
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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