[Wien] generalized regular k-point grids

[Pavel Ondračka]

Hi,

> Yes, WIEN2k is ready to accept any k-grid when using smearing
> methods, 
> however, you need to supply the proper weights.

Great :-)
> 
> I do not know what symmetry your cell has, but I can see only weights
> of 
> 1, 2 and 4 ? Is this correct ?
> It means you have only 4 symmetry operations for this cell ??

Well the posted k-points list was just few first lines, actually the
maximum weight in my case is 8 and that is consistent with the 8
symmetry operations I have (orthorhombic Cmcm).
> 
> PS: Have you tried TEMP instead of TEMPS ? As far as I understand, TEMP
> corrects towards zero Kelvin and should be compatible with TETRA. And
> of 
> course with a very small smearing parameter, TEMPS should go towards 
> TEMP --> TETRA (if the k-mesh is good enough).

I did not, but I was consistent so I believe it should not matter? 

> PPS: Be aware of different coordinate systems for different lattices !
> VASP and WIEN2k may eventually ?? specify the coordinates in different 
> coordinates (cartesian vs. fractions of (non-orthogonal) rec. lattice
> vectors.

I'll check this, thanks for the pointer, but this is looking like it
might be the case and I might need some rescaling. Looking at the
Userguide "We use cartesian coordinates in units of 2π/a, 2π/b, 2π/c
for P, C, F and B cubic, tetragonal and orthorhombic lattices, but
internal coordinates for H and monoclinic/triclinic lattices". I'll
check the VASP KPOINTS format...

Best regards
Pavel
> 
> Peter Blaha
> 
> Am 10/14/21 um 2:52 PM schrieb Pavel Ondračka:
> > Dear Wien2k mailing list,
> > 
> > Is Wien2k ready for a general k-point grid or is some part of the
> > code
> > assuming regular grid?
> > 
> > I was reading some papers about how the generalized regular k-point
> > grids have better efficiency over the standard Monkhorst-Pack ones...
> > For example this paper has also an implementation
> > https://msg.byu.edu/docs/papers/autoGR.pdf
> > 
> > It generates a k-point list in VASP KPOINTS format:
> >   0.000000000000  0.000000000000  0.000000000000     1
> > -0.166666666667  0.166666666667  0.000000000000     2
> > -0.333333333333  0.333333333333  0.000000000000     2
> >   0.500000000000 -0.500000000000  0.000000000000     1
> >   0.062500000000 -0.020833333333  0.035714285714     4
> > -0.104166666667  0.145833333333  0.035714285714     4
> > -0.270833333333  0.312500000000  0.035714285714     4
> > .....
> > 
> > I just do the stupid thing and convert it to the .klist format by
> > multiplying with 1e9 and applying the proper formating, i.e.:
> >           1         0         0         01000000000  1.0
> >           2-166666666 166666666         01000000000  2.0
> >           3-333333333 333333333         01000000000  2.0
> >           4 500000000-500000000         01000000000  1.0
> >           5  62500000 -20833333  357142851000000000  4.0
> >           6-104166666 145833333  357142851000000000  4.0
> >           7-270833333 312500000  357142851000000000  4.0
> > .....
> > 
> > Now everything seems to run OK at the first glance (lapw2 crashes
> > with
> > TETRA ofc but TEMPS seems to be OK) but the energies are not so close
> > (I would expect that at very large number of k-points it should give
> > the same results as standard Wien2k MP grid), but there is a
> > difference
> > of maybe 2mRy/atom. So I guess there is still something somewhere
> > missing for this to work?
> > 
> > Best regards
> > Pavel
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> > SEARCH the MAILING-LIST at: 
> > http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
> > 
>