[Wien] Inconsistency in kgen
balabi
balabi at qq.com
Tue Mar 19 08:09:38 CET 2024
Dear Prof. Peter Blaha,
I think I found another issue with kgen -1 mode especially concerned with I4/mmm symmetry.
As previously mentioned, the '-1' mode of kgen generates uneven k divisions, as you rightly pointed out. However, I've observed potential issues with the weight of the uneven k mesh, particularly in the context of I4/mmm symmetry (and possibly other symmetries as well). This discrepancy appears to lead to inaccuracies in determining the Fermi energy.
Here is how I benchmarked:
1. run_lapw -p till converge for CaFe2As2 and 10 10 10 shift kmesh. save_lapw -d scf
2. x kgen generate 9 9 9 non shifted mesh | x lapw1 -p; x lapw2 -p -fermi | get Ef=0.5076760931
3. x kgen generate 9 9 13 non shifted mesh | x lapw1 -p; x lapw2 -p -fermi | get Ef=0.5028504280
2. x kgen -fbz generate full 9 9 9 non shifted mesh | x lapw1 -p; x lapw2 -p -fermi | get Ef=0.5076760047
3. x kgen -fbz generate full 9 9 13 non shifted mesh | x lapw1 -p; x lapw2 -p -fermi | get Ef=0.5077417577
You can observe the significant difference in the Ef obtained from the 9 9 13 kmesh in the irreducible Brillouin zone (IBZ). However, the Ef calculated from the full Brillouin zone (FBZ) using the same mesh appears normal. Consequently, I suspect there may be an issue with the weight of k-points in the 9 9 13 mesh generated by your modified kgen. On the other hand, equal division kmesh 9 9 9 gives consistent Ef for both ibz and fbz.
What is more, for 9 9 13 IBZ kmesh, when viewing fermi surface. xcrysden 1.6.2 gives error. xcrysden 1.5.60 gives completely wrong fermi surface.
Please help, thank you very much!
best regards
------------------ Original ------------------
From: "A Mailing list for WIEN2k users" <peter.blaha at tuwien.ac.at>;
Date: Mon, Mar 11, 2024 08:33 PM
To: "wien"<wien at zeus.theochem.tuwien.ac.at>;
Subject: Re: [Wien] Inconsistency in kgen
Ups.
Here it comes.
Am 11.03.2024 um 13:26 schrieb balabi via Wien:
> Dear Prof. Peter Blaha
>
> Thank you so much for your reply! But I can not find your attachment of
> bravai.f.gz
>
> best regards
>
> ------------------------------------------------------------------------
>
>
>
> ------------------ Original ------------------
> *From:* "A Mailing list for WIEN2k users" <peter.blaha at tuwien.ac.at>;
> *Date:* Mon, Mar 11, 2024 04:03 PM
> *To:* "wien"<wien at zeus.theochem.tuwien.ac.at>;
> *Subject:* Re: [Wien] Inconsistency in kgen
>
> Hi,
>
> Thank you very much for your report. I can confirm the problem.
>
> Both, for bct and bco lattices (body-centered tetragonal or
> orthorhombic) kgen enforced in default modes equal divisions of the
> reciprocal lattice vectors (as it should be for bcc). This was not a
> good choice and the selection made by option "-1" (mesh density in
> bohr^-1) is correct.
>
> I attach a modified bravai.f.gz file, which should be copied and
> unziped in SRC_kgen, then recompiled (make; cp kgen ..).
>
> PS: The prevous setting was not a problem if your k-mesh is converged
> (besides the larger computational effort), but may lead to extra
> inaccuracy for non-converged meshes.
>
> Peter Blaha
>
> Am 10.03.2024 um 14:48 schrieb 巴拉比 via Wien:
>> Dear wien2k developers and users,
>>
>> I am using wien2k 23.2 and working with CaFe2As2 structure which has
>> I4/mmm symmetry. I am trying to generate klist using kgen. The kgen
>> has several mode:
>>
>> the 1st mode is to specify k-mesh density
>>
>> /NUMBER OF K-POINTS IN WHOLE CELL: (0 for 3 divisions of K, -1 for
>> delta-K)/
>> /-1/
>> / length of reciprocal lattice vectors (bohr^-1): 0.898 0.898 1.203/
>> / Specify density of k-mesh in bohr^-1:/
>> /0.2/
>> / Shift of k-mesh allowed. Do you want to shift: (0=no, 1=shift)/
>> /0/
>> / 17 k-points generated, ndiv= 5 5 7/
>> / delta-K (bohr^-1): 0.1796 0.1796 0.1719/
>> /KGEN ENDS/
>> /0.004u 0.016s 1:03.31 0.0% 0+0k 0+88io 0pf+0w/
>>
>> As you can see, the ndiv=5 5 7
>>
>> The 2nd mode is to specify number of k points
>>
>> /NUMBER OF K-POINTS IN WHOLE CELL: (0 for 3 divisions of K, -1 for
>> delta-K)/
>> /1000/
>> / length of reciprocal lattice vectors (bohr^-1): 0.898 0.898 1.203/
>> / Shift of k-mesh allowed. Do you want to shift: (0=no, 1=shift)/
>> /0/
>> / 102 k-points generated, ndiv= 10 10 10/
>> / delta-K (bohr^-1): 0.0898 0.0898 0.1203/
>> /KGEN ENDS/
>> /0.026u 0.003s 0:09.41 0.2% 0+0k 0+344io 0pf+0w/
>>
>> as you can see unlike -1 mode, the ndiv=10 10 10 which is even.
>>
>> The 3rd mode is to specify ndiv explicitly, and here comes the problem
>>
>> /NUMBER OF K-POINTS IN WHOLE CELL: (0 for 3 divisions of K, -1 for
>> delta-K)/
>> /0/
>> / length of reciprocal lattice vectors (bohr^-1): 0.898 0.898 1.203/
>> / Specify 3 mesh-divisions (n1,n2,n3):/
>> /5,5,7/
>> / Lattice symmetry requires equal mesh in x and z direction/
>> / Specify 3 mesh-divisions (n1,n2,n3):/
>>
>> If I set ndiv as 5 5 7 as -1 mode. It just does not work. kgen insists
>> equal mesh on x and z. So I must input even ndiv like 5 5 5.
>>
>> So the current issue is why the ndiv obtained with the -1 mode in kgen
>> is not uniform for the CaFe2As2 system, whereas ndiv obtained with the
>> k-point mode is uniform, and using the 0 mode, it's impossible to set
>> non-uniform ndiv at all？
>>
>> finally, I am attaching the struct file of CaFe2As2 as below
>>
>> /blebleble /
>> /B LATTICE,NONEQUIV.ATOMS: 3 139 I4/mmm /
>> / RELA /
>> / 7.383336 7.383336 21.922849 90.000000 90.000000 90.000000/
>> /ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000/
>> / MULT= 1 ISPLIT=-2/
>> /Ca1 NPT= 781 R0=0.00005000 RMT= 2.50000 Z: 20.0 /
>> /LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000/
>> / 0.0000000 1.0000000 0.0000000/
>> / 0.0000000 0.0000000 1.0000000/
>> /ATOM -2: X=0.50000000 Y=0.00000000 Z=0.25000000/
>> / MULT= 2 ISPLIT=-2/
>> / -2: X=0.00000000 Y=0.50000000 Z=0.25000000/
>> /Fe1 NPT= 781 R0=0.00005000 RMT= 2.28 Z: 26.0 /
>> /LOCAL ROT MATRIX: 0.7071068-0.7071068 0.0000000/
>> / 0.7071068 0.7071068 0.0000000/
>> / 0.0000000 0.0000000 1.0000000/
>> /ATOM -3: X=0.00000000 Y=0.00000000 Z=0.63490625/
>> / MULT= 2 ISPLIT=-2/
>> / -3: X=0.00000000 Y=0.00000000 Z=0.36509375/
>> /As1 NPT= 781 R0=0.00005000 RMT= 2.17 Z: 33.0 /
>> /LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000/
>> / 0.0000000 1.0000000 0.0000000/
>> / 0.0000000 0.0000000 1.0000000/
>> / 16 NUMBER OF SYMMETRY OPERATIONS/
>> / 1 0 0 0.00000000/
>> / 0 1 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 1/
>> /-1 0 0 0.00000000/
>> / 0-1 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 2/
>> / 0-1 0 0.00000000/
>> / 1 0 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 3/
>> / 0 1 0 0.00000000/
>> /-1 0 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 4/
>> /-1 0 0 0.00000000/
>> / 0 1 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 5/
>> / 1 0 0 0.00000000/
>> / 0-1 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 6/
>> / 0 1 0 0.00000000/
>> / 1 0 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 7/
>> / 0-1 0 0.00000000/
>> /-1 0 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 8/
>> /-1 0 0 0.00000000/
>> / 0-1 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 9/
>> / 1 0 0 0.00000000/
>> / 0 1 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 10/
>> / 0 1 0 0.00000000/
>> /-1 0 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 11/
>> / 0-1 0 0.00000000/
>> / 1 0 0 0.00000000/
>> / 0 0-1 0.00000000/
>> / 12/
>> / 1 0 0 0.00000000/
>> / 0-1 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 13/
>> /-1 0 0 0.00000000/
>> / 0 1 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 14/
>> / 0-1 0 0.00000000/
>> /-1 0 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 15/
>> / 0 1 0 0.00000000/
>> / 1 0 0 0.00000000/
>> / 0 0 1 0.00000000/
>> / 16/
>>
>>
>> best regards
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
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>
> --
> -----------------------------------------------------------------------
> Peter Blaha, Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-158801165300
> Email:peter.blaha at tuwien.ac.at
> WWW:http://www.imc.tuwien.ac.at WIEN2k:http://www.wien2k.at
> -------------------------------------------------------------------------
>
>
> _______________________________________________
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Phone: +43-1-58801-165300
Email: peter.blaha at tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at
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