build a helically coiled carbon nanotube

[Ehsan]

hello;
is there any way to build a helically coiled carbon nanotube or a nanotorus?

i attached two pictures that show these structures.

[Anders Blom]

You could in principle use "Transform by Expression" to map the axial nanotube coordinate onto the helical path. Some care needs to be taken in the transverse directions though.

[Ehsan]

thank you dear Dr Blom

we know a helical path is sth like :
x = sin(t)
y = cos(t)
z = t
so if i want to replace this equation on "Transform by Expression" as long as i can't define a parameter "t", how would be that?

[Anders Blom]

It's not quite that easy, I discovered. However, it was very easy to modify the TubeWrapper plugin to add this feature. I have attached an updated version. Try this:

• Build a (6,0) nanotube
• Swap axes B<>C, Y<>Z
• Repeat 30 times in B (it's a bit too small, but also you get a lot of atoms, so have some patience if you increase the value)
• Change lattice to A=120 Å and C=10 Å
• Center in all directions
• Use the new wrapper, with 360 degrees and 10 Å helical rise (or another value, but use same value for the C vector length)
• Repeat 3x in C to get the attached picture!

[Ehsan]

thank you, it's exactly what i want, but would u let me know how can i update the TubeWrapper? i tried to copy and paste the attached folder to AddOns forlder of ATK, but it didn't work.

[Anders Blom]

You must normally restart VNL when you update or add an AddOn. Instead of copying the folder you can also uninstall the existing TubeWrapper and the choose "Local install" to install the ZIP file. You still have to restart VNL though.