Dear Angelo, you can use VMD software. It can build graphene and carbon nanotubes with any size easily. 

Thank you for your answer, but I was about to understand how I could create the structure using MS because probably I will use it for other problems, so I would to take confidence with the software.

If you have some experience with it, it would be better!

Cheers,

A.

Hai Angelo

Creating nano structures using MS is very easy than any known software to my experience.

Step 1

Create a unit cell for mono-layer graphene

Step 2

go to: Build----->Surfaces-------->cleave Surface

Step 3

enter  1 0 0 in the box provided for (h k l) and click on Cleave which is at bottom

u will get Zigzag nano-ribbon

step 4

goto Build------> crystal -------> build vacuum slab------>build

it will give a zigzag nano ribbon in a cell with the length and width based on cleave tab

repeat same up-to step 3 and enter 1 1 0 and cleave which give arm chair nano-ribbon and again do step 4

Good Luk

Steps of Material Studio for build CNT

Download graphite cif file from this link “http://rruff.geo.arizona.edu/AMS/minerals/Graphite”

1) File -> Import -> Structures -> ceramics -> graphite.msi;

2) Build -> Symmetry -> Make P1;

3) Remove one of the two layers;

4) Build -> Symmetry -> Find Symmetry -> Impose Symmetry;

5) Build -> Symmetry -> Supercell 2*2*2;

6) Build -> Crystals -> Rebuild Crystal -> Lattice Parameters -> a=4.26, b=2.46, c=25, alpha=beta=gamma=90 -> Rebuild;

7) Build -> Symmetry -> Supercell 5*5*1.