Siesta

about Projected transmissions

Asked by benqi

hellow
as I use the following setup to project transmissions:

%block TBT.Projs
M_L
%endblock
%block TBT.Proj.M_L
atom [59,60,69,70,81,82]
Gamma .true.
proj HOMO
level -1
end
proj LUMO
level 1
end
%endblock

I get the folowing information:

Error occured in NCDF:
NetCDF: Not a valid ID
Status number: -33
ncdf: Stopped due to error in NetCDF file

Program aborted. Backtrace:
#0 0x7F611CEB4467
#1 0x7F611CEB5C42
#2 0x7F611CF8A4E8
#3 0x658799 in __nf_ncdf_MOD_ncdf_die at nf_ncdf.f90:?
#4 0x658AB2 in __nf_ncdf_MOD_ncdf_err.part.1 at nf_ncdf.f90:?
#5 0x67DA1E in __nf_ncdf_MOD_ncdf_open_grp
#6 0x6136B9 in __m_tbt_proj_MOD_proj_update
#7 0x60795C in __m_tbt_trik_MOD_tbt_trik
#8 0x603A87 in __m_tbtrans_MOD_tbt

I wonder if it is due to my setup or the code.

Question information

Language:
English Edit question
Status:
Answered
For:
Siesta Edit question
Assignee:
Nick Papior Edit question
Last query:
Last reply:
Revision history for this message
Nick Papior (nickpapior) said : 		#1

Have you defined the TBT.Projs.T block? It is required when using projections.

I will try and remember to emphasise this in the manual for the next release.

Revision history for this message
benqi (benqi) said : 		#2

dear Nick Papior
I still can not know how to project the transmission. I want to calculate the electronic transport properties of a electrode- molecule -electrode system. The molecule has only two atom. the transportation can be directely between the two electrode or via the molecule, and I want to know the ratio of the transmission via the molecule, so I project the transmission on to the molecule, the setup of my task is as follows:

%block TBT.Projs
 M-L
%endblock

%block TBT.Proj.M-L
atom [69,70]
Gamma .true.
proj HOMO
level -1
end
proj LUMO
level 1
end
proj H-plus-L
level from -1 to 1
end
%endblock

%block TBT.Projs.T
 from Left.M-L to
 Right
end
%endblock

the programe stopped with the follows error:
"The scattering states are not fully encapsulated on a left projection. This is not allowed "

whats wrong with my setup? can you give me an example setup to project the transmmision on to the molecule?

Revision history for this message
Nick Papior (nickpapior) said : 		#3

Sadly projections only work if the molecule is "big enough", meant in the sense that the self-energies must not extend beyond the projection region (molecule).

This is explained in the manual in the beginning of Sec. 4.6.2:
"One important aspect of projection is that the self-energies that are to be projected must be fully located on the projection region. TBtrans will die if this is not enforced."

So basically, you cannot project onto the molecule you have because it is so small.

Revision history for this message
benqi (benqi) said : 		#4

thanks
 I see

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