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.bl...@tuwien.ac.at WWW:http://www.imc.tuwien.ac.at WIEN2k:http://www.wien2k.at
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