[Wien] 2D Fermi surface plot

[Lo_wan_2005XW]

Dear Prof. Blaha

Thank you very much for your reply!

To set the NX,NY,x-len,y-len in case.spaghetti_ene

The first-line of fort.2 created by hex_fs_mesh is:
         1    0    0    0  120 1.00-7.00 1.50       61 121
Thus I just set NX=61 and NY=121, is it correct?

According to the manual, the unit of x-len and y-len is bohr^(-1), thus originally I think it is the reciprocal lattice. But when I set x-len=0.3382
, I get very small plot. Thus, I think x-len and y-len is the size of the plot. Actually both 
x-len=10 and x-len=20 can work, and x-len=20 give twice bigger plot than x-len=10. So I confuse why you said "the length of rec.space must be ok"?

Thank you again for your help!

Bests

Xiangang
-----------------------------------------------------------
I don't quite understand why you say that 6 bands cross EF along G-M ???
According to your bandstructure there are only 4 bands, but two of them cross
EF twice. But still, this is the "same" band.

> With this setup I finish the calculation, attached please find the six-band which contribute to the Fermi surface.
>
> 1) The output-plot is square, could you please tell me the coordinate of the four corner in of the square. I think one is (0,0,0); another is (1/2,0,0). How about other two? Where
> is the x-axis in the plot? I guess the Gamma-point is located at the left-bottom corner of the square, and M-point is the right-bottom corner, right?

This depends a lot on the settings in  case.spaghetti_ene is :*
 > 19 13 0.33820 0.19526 27 23 0 0

The first two numbers must be set properly according to your mesh.
Also the length of rec.space must be ok.
The "interpolation" numbers should be 2N-1 and not "arbitrary numbers".
and finally, the "0 0" is very important.
If you don't understand them, experiment with them and you should be able
to understand them.

For better orientation you should do a bandstructure plot, but not in the
directions you attached (going into z>0 ???), but plot several directions in the
Gamma-X-M plane. Then it should be easy to orient you.

Also, use the fs option of xcrysden to get an 3D overview over the different
sheets and then it is easier to "imagine" how the cuts should look like.

> 2) Why the lines in save_filename_64.plot.ps, save_filename_63.plot.ps is dot-line; and the lines in other files is full-line?

plotgenc plots negative contors as dashed, zero as dotted and positive ones as full
lines.
I don't know how you produced these plots.
I also don't quite understand why you have save_filename_63, 64, but then 77,78,79,80 ???
This does not look ok.

> 4) It is not convenient to plot the fermi-surface separately. May we combine the sheet from different bands to a single plot?

cat save_filename_63.plot.ps save_filename_64.plot.ps > combined.ps
and edit combined.ps
I attach the edited combined.ps file, where I simply commented (%) a few lines
and added a color switch to plot the second sheet in a different color.

With this tamplate you should be able to make it for other examples.


                                       P.Blaha

 		 	   		  
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