Dear all,

I would be thankful if you help me with this question. Namely, I am
studying a graphene TranSIESTA example located at
http://dipc.ehu.es/frederiksen/tstutorial/index.php/Graphene. A
tarball is provided there which contains two folders to calculate the
transmission of graphene sheet. My question is regarding the
calculations in the "small-supercell" folder. Particularly, after the
scattering calculation is finished, when I use tbtrans to calculate
the transmission, if I change the Monkhorst-Pack sampling in the .fdf
file to the following:

%block kgrid_Monkhorst_Pack
   1   0    0  0.0
   0   20  0  0.0
   0   0   10 0.0
%endblock Kgrid_Monkhorst_Pack

the transmission "does not come to zero at zero energy". But "it comes
to zero when using the original Monkhorst-Pack grid", i.e. :

%block kgrid_Monkhorst_Pack
   1   0    0  0.0
   0   20  0  0.5
   0   0   10 0.5
%endblock Kgrid_Monkhorst_Pack

As can be seen, I have only changed the values of displacements in the
%block kgrid_Monkhorst_Pack and nothing else was changed in the .fdf
file. Apparently, by changing the displacements, I have missed the K
point of graphene but I can not figure out the mechanism of this. Any
help to clarify what is going on is indeed welcome.

Bests,
Mohammad,

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