Dear Arad, First I would like to mention that the function Bias_R you define in the lead has not the same symmetry as that of the lead. so, it may cause a problem. There is a warning about that in the kwant documentation:
""" Warning: If functions are used to set values inside a lead, then they must satisfy the same symmetry as the lead does. There is (currently) no check and wrong results will be the consequence of a misbehaving function. """ The second thing I acn say about your program is the following: Let us put the bias very high. So the onsite potential you are putting will be very high and therefore the conduction band of the left lead (band_L=[-4t. 4t]) and the conduction band of the right lead (Band_R= [-4t+V,4t+4] ) will have no energy in common and therefore your transmission is exactely zero for all the energies! In the contrary, from the physics of the problem, we are expecting to get larger conductance by increasing the bias ! Just by this argument, you can see that the way you are attacking this problem is incorrect. To obtain what you want, you need to put the two leads free of potential and put your bias in the Fermi distribution. You calculate your transmission for all the corrsponding energies and then do the integral. You will find that your conductance is linear with V for small values of V. I hope this helps. Adel On Fri, May 5, 2017 at 5:13 PM, Arad gold <arad.m...@gmail.com> wrote: > Thank you very much for the prompt reply. > I expect the current change linearly by increasing the bias. > I have attached the code. > Thank you very much for your help. > > Best Regards, > Arad > > On Thu, May 4, 2017 at 2:20 PM, Joseph Weston <joseph.westo...@gmail.com> > wrote: > >> Hi, >> >> > My question is about calculating total current for a finite bias in a >> > nanowire. >> > I looked at the Datta book and try to implement it in KWANT but I can >> not >> > get >> > a reliable answer, I think I made a mistake somewhere but I can not >> find it. >> >> If you want help you are going to need to be more specific I am afraid. >> What do you expect, and what does your program give you? >> >> I couldn't run the code you dumped into the body of the email just by >> copy/pasting it into a text file because the formatting is all messed >> up. Please submit any scripts as actual attachments which run and >> produce what you wish to show. Only inline *relevant snippets* into the >> body of the email; not a whole script. This greatly reduces the amount >> of effort people have to go through to help out. >> >> Happy Kwanting, >> >> Joe >> > > -- Abbout Adel
