In my research work I've come to the simple test problem which can be solved both using Kwant and analytically. It's about scattering of the electron wave in the chain of atoms in which hopping integral is t1 for x < 0 and t2 for x > 0. Almost all the solution is in the picture in the attachments. Realization of this analytical solution is presented in testChain.py which plots the dependence on scattering energy of the transmission coefficient

|tau|**2 * v2/v1, vj = -2*tj*sin(phi_j) - velocity of the electron.

The testChain-kwant.py also plots transmission coefficient versus energy in the same system, but the results are not coincide.

So, my question, is it possible to reach the accordance between the solutions in both cases?

P.S. Analytical solution seems to be correct, at least

|rho|**2 + |tau|**2 * v2/v1 is 1 identically.

P.P.S. Is it possible to draw the different hopping kinds with different colors and line styles? It can be useful for controlling errors when building the geometries with hoppings between second-neighbors...