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NEGF in Graphene Date: 2015/07/27 23:45 Name: Khalid   <kimu206@gmail.com> 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. Khalid M.Sc student BUET

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Re: NEGF in Graphene ( No.1 ) Date: 2015/08/06 11:05 Name: T. Ozaki Hi, > 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. Regards, TO Re: NEGF in Graphene ( No.2 ) Date: 2015/08/08 23:34 Name: Khalid  <kimu206@gmail.com> 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. Khalid

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