Hi All,

I am currently trying to implement the advice given by Joseph in https://www.mail-archive.com/kwant-discuss@kwant-project.org/msg00075.html​ to write a code which generates the current density going into each site in my graphene system. 

My issue is with returning the nearest neighbor hopping elements in graphene. In the example Joseph posted for a square lattice, there is an obvious coordinate for the nearest neighbor sites. It seems to me that in graphene (or any honeycomb lattice), this is not so obvious. 

I have been looking for a function built into Kwant that would give me what I need, but haven't had much luck. I've figured out lots of ways (for example, using sys_leads_sites on my finalized system) to generate the number assigned to each site and the corresponding position, but not a good way to determine which are nearest neighbors. I'm guessing the answer is very simple using some of the machinery built into Kwant, I'm just not seeing it. 

Does anyone have any tips they would be willing to give me? I am not looking for a complete current density code, just a nudge in the right direction. ​

Thanks very much!