[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
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
> IHPC Values  ::  Impact   ::   Honesty   ::   Performance   ::   Co-operation
> This email is confidential and may be privileged. If you are not the intended recipient, please delete it and notify us immediately. Please do not copy or use it for any purpose, or disclose its contents to any other person. Thank you.
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>

-- 
-----------------------------------------
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
-----------------------------------------


More information about the Wien mailing list