[Wien] two different GAP value in a scf-iteration

hiroshi.nakano at sharp.co.jp hiroshi.nakano at sharp.co.jp
Fri Oct 5 09:23:44 CEST 2012


Dear Prof. Blaha

Thank you for your advice.
I will try again with more k-points and update to the version 12.1.
The version I calculated was 11.1.

Best Regards
Hiroshi Nakano

-----Original Message-----
From: wien-bounces at zeus.theochem.tuwien.ac.at [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha
Sent: Friday, October 05, 2012 2:23 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] two different GAP value in a scf-iteration

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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