Could VNL be used to construct capped tube?

[littlechl]

Hello everyone:could VNL be used to construct capped tube?

[Anders Blom]

Yes, although you need to work a bit. The procedure is to take a suitable fullerene from the Database, remove half of the atoms to create a hemisphere, then place it roughly where you need it at the end of a corresponding diameter nanotube, and use the Brenner potential in ATK 11.2 to relax the geometry.

The nanotube needs to be a bit longer than just one unit cell, to allow the connected part to relax, while you should keep the coordinates of at least 2-3 layers on the unconnected side frozen.

The Brenner potential is extremely fast, and should be able to optimize the system in under a minute, even if you have hundreds of atoms.

Alternatively, perhaps some users on the Forum already have some built capped systems that they can share

[littlechl]

      Very thanks for your help!But I still can't solve the problem.
      In ATK,when we build a nanotube, the nanotube is always parallel to Z axis.While it's not easy to set the hemispere I get from the fullerene perpendicular to Z axis.Do you have any good method?
      I place the hemisphere to the nanotubethen place it roughly where I need it at the end of a corresponding diameter nanotube, and use the Brenner potential in ATK 11.2 to relax the geometry,but the result is not what I want.The cap are destoried.What shall I do?

[Anders Blom]

I played around with this a bit myself, and got some pretty nice structures for (5,5), (9,0), and (10,0). I'm going to give (6,6) are try as well. Which tube are you interested in?

This could be made into a tutorial, however it requires some delicate touch; it's not difficult in principle (you follow exactly the steps you outlined), but the devil is in the details

Probably a better way is to just post the final structures so people can use them. I'll do that under the tutorials later, but let me know which one you want, and I can attach it to this thread.