[Wien] Inconsistency in kgen
Peter Blaha
peter.blaha at tuwien.ac.at
Mon Mar 11 09:03:19 CET 2024
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
> ------------------------------------------------------------------------
>
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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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