[Wien] DOS over certain volume in the BZ

[Peter Blaha]

You can create any klist you want and also calculate the qtl's for this 
k-mesh (NOT WITH TETRA option in case.in2). Note  that the resulting EF 
will be "wrong", but integrals could still be obtained using "ALL" and 
putting the proper EF into case.in2 by hand. You will then have to 
relate these integrals to the "volume" your k-mesh is spanning.

However, you cannot use   x tetra. (tetra uses beside case.klist also 
case.kgen. It needs this info to find which k-points form the 
corresponding tetrahedra).

Thus, when you are interested in the DOS (and not just in integrals),
you have to modify tetra; or you could just use the resulting qtl file 
and write your own simple program using a "histogramm-method" or/and 
some gauss-broadening. When you have a "dense" k-mesh, the tetrahedron 
method is not really necessary for integration.

Lukasz Plucinski schrieb:
> Dear WIEN users,
> 
> Please see my initial question below.
> 
> Modifying tetra will be probably the last resort for me.
> 
> I would like to construct a new case.klist file using my own script, 
> being able to precisely control which points in the BZ are taken into 
> account. I understand that case.klist file contains weights for optimal 
> sampling of the zone using less k-points, however, I am interested in 
> simple cases and the number of k-points is not an issue, I could do very 
> dense sampling and constant weight for all points.
> 
> Also sometimes my BZ volume would be on the boundary between the first 
> and second BZ thus I am not really interested to work in the IBZ.
> 
> I wonder if (after running the scf cycle) I could create a new 
> case.klist_band file (containing dense, uniform mesh of points in the 
> interesting volume of BZ, e.g. sphere, cube, or cylinder), and then run
> 
> x lapw1 -band
> x lapw2 -qtl -band
> x tetra
> 
> to get the DOS of this volume ? Does this makes sense ?
> 
> Regards,
> 
> Lukasz
> 
> 
> 
> Peter Blaha wrote:
> 
> Yes, you can run first an scf cycle with a medium k-mesh, then run   x 
> kfen and create a dense mesh and continue just with lapw2, 2,tetra
> 
> However, you will have to modify tetra to sum the  DOS only over 
> certain tetrahedra (covering the volume you are interested in).
> 
> 
>>> > > Hello,
>>> > > 
>>> > > I would like to calculate the density of states over a certain volume in
>>> > > the BZ. I think that it would require to sample this volume with many
>>> > > k-points, i.e. prepare a new case.klist file. However, I guess that by
>>> > > default the DOS utility is using the k-points which were used in the SCF
>>> > > cycle.
>>> > > 
>>> > > Would it work to create new case.klist_band, then run
>>> > > x lapw1 -band
>>> > > x lapw2 -qtl -band
>>> > > x tetra ?
>>> > > 
>>> > > I guess the only precaution when creating new k-list file would be to make
>>> > > sure the k-point sampling is dense enough (which gets more important when
>>> > > strongly dispersive bands are present in the interesting BZ volume).
>>> > > 
>>> > > Regards,
>>> > > 
>>> > > Lukasz
>>> > >   
>>>     
> 
> 
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: 
http://info.tuwien.ac.at/theochem/
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