I am currently learning DFTB+ using the tutorials on the official website :
Carbon Nanoribbons : https://dftbplus-recipes.readthedocs.io/en/latest/defect/carbon2d-elec.html#zigzag-nanoribbon
Molecular Junctions : https://dftbplus-recipes.readthedocs.io/en/latest/transport/molecule-junction.html
How do I go about creating the geometry files for the systems used in these tutorials?
So far, I have been using Avogadro for creating xyz files but I haven't created "planar periodic" structures as illustrated in the tutorials.