I have the feeling that your problem is related to the Bravais lattice
which is F-centered and Primitive in the first and second cases.
It is not related to the way the calculation is done (complex or not).
Indeed, when you are using the space group Foum-3m, WIEN2k is doing the
calculation in the related primitive cell which is 4-times smaller than
the F-centered one.
In constrast when you are doing the calculation with the initial
structure but keeping the P1 symmetry, WIEN2k do the calculation for the
full-cell. Thus in the reciprocal space the directions will be different
and thus the path.
On the other hand, could you provide the 2 structures to check that you
didn't forget atoms in the case of the P1 symmetry calculation.
Best Regards
Xavier
Le 6/28/2013 7:18 PM, venkatesh chandragiri a écrit :
Dear wein2k users,
I have calculated the band structure of the Fe2VAl lattice (fm3m, 225)
for the two cases.
*case one* : using the space group (225) defined structure with three
atoms.
*case two* : by seeing the structure of Fe2VAl in xcrysden, i have
generated the case.struct file with 16 atomic unit cell (8-Fe, 4-V,
4-Al) with a 16 number of co-ordinates such that the structure looks
same as in *case one*. But, in this structure file, i have used space
group as a primitive (1).
Using the Powder cell software, i also checked the XRD of the
structures from the both cases and similar diffraction pattern were
found. I run the volume optimization and min positions before running
the spin polarized SCF calculation. However, In the First case (space
group structure), we run the calculation without complex (no
inversion). But, in the second case (primitive), we did the
calculations with keeping complex ON.
Now, i done the spaghetti plots for these two structures. For the
space group case, we have observed indirect band picture between gamma
and X k-points (X point will always followed by gamma). This nature is
already reported in the literature also. But, for the second case with
primitive structure, i have found the direct band like picture in
which both band are touching at the gamma point.
In preparing the case.klist and case.klist_band, i have used similar
k-point co-ordinates for the both cases.
Why the bands above the Fermi level would not shift to x point in the
primitive case. Is there any effect of removing the symmetry on the
band structure even though we did calculations on the similar
structure...?
or else in the first case, calculations did with complex OFF while in
the second case with complex ON. Is this difference will change the
band structure nature...?
I could not attach the obtained figures, because i sent same mail with
figures in few days before but it is not published in wien2k mailing
list due to limitations in the mail content size.
thanks in advance and waiting for your replies.
regards,
Ch. Venkatesh,
C/o. Prof. V. Srinivas & Dr. S. K. Srivastava
Department of Physics & Meteorology,
IIT Kharagpur.
ph: +91-3222-283848 (Lab)
+919445909693
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