Hi, The theory can be found is many places, for instance in the appendix of http://journals.aps.org/prx/abstract/10.1103/PhysRevX.2.031004 <http://journals.aps.org/prx/abstract/10.1103/PhysRevX.2.031004> There is an example in the Kwant paper, http://iopscience.iop.org/article/10.1088/1367-2630/16/6/063065;jsessionid=5... <http://iopscience.iop.org/article/10.1088/1367-2630/16/6/063065;jsessionid=5...> (figure 13 and 14) with the full code given in Appendix D5. Good luck, Xavier

Le 20 oct. 2016 à 16:34, Lee Kin <llwaeva@gmail.com> a écrit :

Hi there, I start to use kwant not long ago. I am still following the instruction to learn the basic usage of the code. I have a simple code in hand to handle the square lattices with some given potential of certain form. I am thinking to add the constant magnetic field along z direction. In my text, it is said that such field could be described by vector potential such that the potential could be modified as alpha*(x**2 + y**2) in which alpha is proportional to the magnitude of the field. I add this to each lattice site but then it diverges in solution. I saw other material online and it said the magnetic field could be added by modifying the hopping phase. I don't quite follow that. Any suggestion is welcomed. Thanks.