Dear All, I am really liking this Kwant program and I find it very intuitive. However my python is a bit rusty. 1) I would like to know what is the simplest way the number of sites, the positions, and the tuples of these sites. I would like to print them all out. 2) In this graphene flake example (http://kwant-project.org/doc/latest/tutorial/tutorial4 http://kwant-project.org/doc/latest/tutorial/tutorial4) if i wanted to make a hall bar setup, how would I exactly attach the leads purely in the x-axis and purely only the y-axis. (more of an aesthetic question). 3) in terms of the hopping, when one has sys[lat.neighbors(1)] =t sys[lat.neighbors(2)] =t is the hopping mediated by the distance i.e. t_1=t/a_1 and t_2=t/a_2. 4) I have calculated the energy DOS for a lead and this looks correct, what I’m more unsure of is this the same as the DOS of the propagating modes. And I see how to find the velocity and things from the documentation, but is there a way to find the energy. Sorry if this is a stupid question I could not find anything on the forum 5) similar to question 1) how do I find things like the number of propagating modes. 6) what is the best way to go about writing observables, sorry this is quite a general question and most likely up to the user, but for instance the pauli matrices are quite simple. However the position operator, or velocity operator changes with the way the Hamiltonian is described, is there something simple general method to calculate these? Thanks very much, and sorry if I did not see these answers in the mailing list Regards, Jacob JGIU INSPIRE GROUP - Prof. Sinova FB 08 - Institut für Physik Staudinger Weg 7 55128 Mainz ____________________________ room 01-523 (1. OG) phone +49 (0) 1517/ 39-27424 fax +49 (0) 6131/ 39-26267 email jgayles@uni-mainz.de mailto:sinova-group@uni-mainz.de