Nanotube axis transformation and zig zag Vs armchair

General Discussion
1

hi
i am new to Avagadro use. Wish to develop Carbon Nanotubes.

  1. How can i orient the Nanotube centre axis align with Z-direction of axis?
  2. How to change the chirality indices to get either Zig-zag or Arm-chair edges for the tube?

Regards