On 06/13/2013 07:31 AM, wasim raja Mondal wrote:
(1) For the generating of *.nkp file, after running Write_win, one has
to run wannier90.x - -pp subdir which will creat the *.nnkp file if you
have used prepare_w2w case subdir. This is not mentioned in the user
guide. only wannier90.x will not work. This is a small thingh. But it
creates lot of tension in the first time user mind like me.
What user guide are you reading? The one I downloaded from
<http://www.wien2k.at/reg_user/unsupported/wien2wannier/wien2wannier_userguide.pdf>
says (p. 3, under "Initialization (init_w2w)"):
wannier90.x(preliminary run): wannier90 requires the input data to be
given on a special k-mesh which includes information with respect to
nearest-neighbor k-points. A preliminary call of wannier90 with the
option -pp stores this mesh to the file case.nnkp.
(2) Before running init_w2w, one hast to do subdir.sym file. In the file
one has to set number of symmetry operation is 1 and first operation has
to to be identity. This is discussed by phillip in the wien2k forum and
in the UG also. I think this symmetry is strongly related with k-points
generation. I may be wrong.
I assume you mean the "case.ksym" file. This is generated (rather, you
are asked to generate it) in init_w2w.
(3) I am felling that we are generating k-points in the init_w2w, which
is showing the number of k-points for LAPW computation. There is
previous generated k-points also which is called k-points for band
structure calculation. The number k-points for LAPW should be less than
the number of k-point for band structure k-point. In this point I may be
completely wrong. I want some experts comment on that.
The Wannier projection is done on a full-BZ unshifted k-mesh as
generated in init_w2w. This k-mesh can be rather sparse (8x8x8 already
gives well-converged results for SrVO3, for example), but since no
symmetries are considered, you still tend to end up with a lot of
k-points to run lapw1 on compared to your standard Wien2k run.
write_win also reads the case.klist_band file, tries to sift out the
"special" points (it takes those that have labels) and writes those to
case.win (section kpoint_path). Wannier90 will then (if bands_plot is
True) make a band structure for a BZ path generated from those points.
The discretization of that path is controlled by the variable
bands_num_points.
(4)If third point is right, than one has to increase the number of
k-point in the band structure . In this point I am struggling at the
moment. For example I have run SrVO3 example in wien2k. In the scf I
have used 8000 k-points. In the band structure calculation I have
generated k-points in the simple cubic not with xcrysden. In the
init_w2w run, it is showing 10 k-points for band structure calculation.
Now the point is that how can I increase the k-point for band structure
calculation?
Note the last thing I said above -- the number of k-points in
case_band.dat is independent of all the "klist" files; it is instead
controlled by bands_num_points in case.win.
HTH,
Elias
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