[Wien] xcrysden bug of Wien2k FS calculation ??

[Moritz Hoesch]

Hi 明文美,

sorry for the late answer. This is probably a problem of xcrysden. It
uses a very old-fashioned way of giving the k-list to lapw1 by inserting
it into the case.in1 file. When I use XCrySDen-1.4.1 with Wien2k07, it
always fails to calculate the right Fermi level (x lapw2 -fermi).
Sometimes putting in the right Fermi level works (look it up in
'case.scf' or 'analyze case.scf :FER'). Sometimes even this doesn't
work. Xcrysden was still working correctly with Wien2k05, so when I
really need it I roll back to that version.

Hope this helps, if not, write to Tone Kokallj and see if he can help.
It would be nice for all of us working with Fermi surfaces.

If I want to calculate Fermi surfaces and in particular two-dimensional
cuts that are most interesting to determine the Fermi wave vectors
precisely, I generate a k-point mesh in a plane in momentum space. The I
copy this k-point list to the file case.klist_band. I pass it through x
lapw1 -band, x spaghetti -band (after editing the case.insp file). Then
I read in the case.spaghetti_ene file by some plotting software (in my
case matlab) and plot the E_B=0 contour of all or selected bands on the
plane. In principle I don't need spaghetti, but I like the convenient
output file.

Good luck Moritz



明文美 wrote:
> Dear all:
>
>
> today I found a big mistake when using *xcrysden *to get the Fermi
> surface of MgB2*,*
> which* *was extensively investigated in past years. The calculatd band
> structure and DOS
> are in excellent agreement with those reported in previous papaers.
> After finishing
> the SCF calculation, I tried to use the interface tool -render fermi
> surface- for WIEN2k in Xcrysden
> to get the corresponding Fermi surface(FS), however, the FS showed big
> difference from that in literatures.
>
> I also tried the examples of Na and found that its FS deviated from
> spherical FS,
> and the FS of Al also presented big difference from that reported
> before. The similar situation occured
> for LaOFeP.
>
> Finally, I tred to get FS through SKW interpolation method (W. E.
> Pickett et.al. Phys. Rev. B 38,2721 (1988)),which only used the
> eigenvalues of irreducible k points from lapw1.Then the calculated FS
> was just excellent,almost a spherical FS.
>
> The FS of Al through this method was also very satisfactory through
> the SKW method.
>
> now I am using WIEN2k_07_12_14, and the xcrysden is XCrySDen-1.4.1.
>
> Did anyone encounter the same siutation? or perhaps I was just my fault?
>
> Any suggestion is greatly appreciated !
>
>
> Wenmei .
>
>
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-- 
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Moritz Hoesch        Tel.    +33 476 88 22 97
postdoc ID28         Fax.    +33 476 88 29 04

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