Dear KS Chan, The lead momenta, just like lead velocities are the lattice momenta and have in general no relation with the coordinate system. The wave function is proportional to the exp(i k n), with n the number of the lead unit cell and k the momentum. I hope that helps, Anton On Thu, Mar 9, 2017 at 8:53 AM, Prof. CHAN Kwok Sum <apkschan@cityu.edu.hk> wrote:
Dear Kwant developer,
Thank you for your effort in developing Kwant.
I have a question about the definition of the direction of momentum in the smatrix.lead_info. Assume a lead lies along the y direction with primitive vector (0,1). The symmetry operation of a lead is (0,1) if the lead goes towards the positive direction and is (0,-1) if the lead goes towards the negative direction. For the momenta contained in smatrix.lead_info for these two leads , do they use the same coordinate system? Positive momenta mean the direction (0,1), negative momenta mean the direction (0,-1). For velocity, in smatrix.lead_info, it has nothing to do with the coordinate system. Positive means outgoing, negative means incoming in the lead.
Thank you
KS Chan
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