Hello
Hi,
I should have explained more accurate. Of course, there is translational symmetry; I meant that CNT cross section is not round anymore. I have attached a .cif file to show what I mean. I'm pretty sure you know how to visualize this structure, but > for the ones who don't, they can use visualization softwares like VESTA
Kwant just does tight binding models where *you* provide the tight-binding parameters (these may come from discretizing a continuous Hamiltonian, or from a DFT calculation or whatever, Kwant is completely agnostic of this). This means that Kwant doesn't know anything about whether the CNT is "squashed" or not if you don't change the tight-binding model itself. Calculating the way in which such a deformation affects the tight-binding parameters is beyond the scope of Kwant and you would need to use a different tool to do this for you.
Hope that clarifies,
Joe
Dear Joe, Thanks for explanation; but my question was not about tight binding. I have constructed my tight binding model and I know matrix elements between all pairs of atoms. My question was about how to enter the geometry of a (1D) CNT in KWANT. Suppose that I want to enter the attached output.cif file, as a lead. How should I enter the atomic positions and ensure that the periodicity of the CNT is preserved? Many thanks