[Wien] Possible bugs in Bandstructure

[Michael Gurnett]

Both problems occur both in w2web preview and looking at the ene file in 
origin. In the case of the first problem one clearly see a difference 
between just having the k vector increase than selecting the correct path in 
the symmetry points in xcrysden (which gives the correct appearance). With 
just having the k-vector increase just seems to reflect the bandstructure at 
a given point and then go back to gamma.

As to the second problem, I have noticed that the figure generated by w2web 
can be wrong (it sometimes puts all the gamma points at lower and lower 
values for increasing k-vector, but this is not seen in the ene file so my 
guess is there could be just a small problem in a script). I converge to 
fc=0.5 which means that both the total energy and the charge distances are 
VERY small. Iäm using 24 k point first to do  the scf (calculations were 
already converged at 12), with a Rmt*kmax of 5.43 (5 was found to be good 
enough). The system is comprised of 70 Ge atoms. The kpath has 150 sampling 
points.

Mick


----- Original Message ----- 
From: "Torsten Andersen" <thor at physik.uni-kl.de>
To: <wien at zeus.theochem.tuwien.ac.at>
Sent: Sunday, February 20, 2005 2:52 PM
Subject: Re: [Wien] Possible bugs in Bandstructure


Of course this may be a dumb comment, but does this appear after
printing or only in ghostview?

If it appears in printing, I would suspect that your calculation is not
converged well enough... and that maybe your basis set is not big
enough... but it is difficult to tell from such a short description.

Best regards,
Torsten Andersen.

Michael Gurnett wrote:
> I wsa doing some bandstructure calculations, an seem to have come up 
> against som strange behaviour. Firstly, In the SBZ of the 1x1 unit cell 
> for Si(111) moving in the K direction and moving outside the first 
> Brillouin zone one would expect that that the path should include the 
> points Gamma->K->M->K->Gamma. However, based on the bandstructure shown, 
> one get as a result Gamma->K->Gamma->K. Secondly, for the 3x1 
> reconstruction, I found that depending on the path taken results at a 
> given symmetry point may differ e.g at the symmetry point c I found that a 
> difference of -0.27 eV was obtained in one direction compared to the other 
> direction, and that several states were missing. Is this a known problem?
>  Thanks
> ----------------------------------------------------------------
> Michael Gurnett
> Dept. of Physics,
> Inst. of Engineering Sciences, Physics and Mathematics,
> Karlstad University,
> S-651 88 Karlstad, SWEDEN
> Tel. +46 54 700 2175, Fax. +46 54 700 1829,
> Mobile phone +46 70 590 6495
> E-mail: michael.gurnett at kau.se <mailto:michael.gurnett at kau.se>, WWW: 
> http://www.ingvet.kau.se/fys/
> -----------------------------------------------------------------

-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/

Symposium on Excited-state properties of solids, Mannheim 2005:
See: http://cmt.physik.uni-kl.de/XSM05/

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