Hi Giacomo
Now that you pointed that out... I can see that my launch script was at fault indeed. I wasn't actually passing the correct file name to the launch script. It is running well now, thanks a lot!
C.
Thank you very much for your attention to this issue! I'm glad it's not my understanding that's wrong. I've already begun implementing your proposed approach.
To generate a supercell of a nanotube, you should first build the supercell of the slab and then generate the nanotube (without applying the supercell). In this case, you should adjust (n,m) according to the desired diameter.
With CRYSTAL (from the PROPERTIES module actually) one can output the Hartree+EN potential in the all-electron case in 2D or 3D grids with POTM and POT3 keywords, respectively. In the latter case, the output is in .cube format. But I am afraid that currently there is no keyword to plot the XC part of the potential on a grid.