This thread is locked.Only browsing is available.
Top Page > Browsing
NEGF in Graphene
Date: 2015/07/27 23:45
Name: Khalid   <>

Dear Researchers,
I appologize that theoretical background is not strong enough and I have to clarify my understandings. I have run the NEGF calculation example of graphene and I am confused about some points:

1. I have applied a drain to source bias of 1 volt, and calculated the current. It is shown that the average current for up spin is 3.325000e-08,
So would not the total current be 3.325e-8 * 2(for spin) * number of k-points?
In the example it was given: NEGF.tran.Kgrid 30 1
So I have 30 k points. So I think the total current should be 3.325*2*30 = 1.996e-6 ampere.
But when I have used: NEGF.tran.Kgrid 60 1
This time, the average current per spin is: 3.644113e-08,
The total current becomes = 2.18e-6 Ampere,

2. In this graphene case, what should be the transmission vs. energy spectrum? I am willing to draw a figure like figure 30 in the manual. Since I have 30 tran#_% files, should I have to add all the transmissions in these files?

Thanks in advance.
M.Sc student
Page: [1]

Re: NEGF in Graphene ( No.1 )
Date: 2015/08/06 11:05
Name: T. Ozaki


> So would not the total current be 3.325e-8 * 2(for spin) * number of k-points?

No, it wouldn't be. Since the average current is calculated by integrating all the contributions
in the Brillouin zone as shown in Eqs. (51-53) in PRB 81, 035116, you should not multiply
the number of k-points.

Each of 30 tran#_% files contain each transmission. If you would like to see the average one,
you have to sum up all the contributions and divide it by the number of k-points.


Re: NEGF in Graphene ( No.2 )
Date: 2015/08/08 23:34
Name: Khalid  <>

Dear Sir,
Thank you very much for your kind help. I have gone through the paper, and found that the total transmission is an integration of the k-resolved transmission. I have done that numerically, and there is some mismatch in the current result, I believe that is due to the numerical inaccuracy in my calculation (I used simple trapezoidal rule to integrate T(E)*(f1 - f2) to determine the current).

Thanks again sir, it was very generous of you to answer my question.


Page: [1]