problem in creating TiO2 nanotube from (101) monolayer

[abbasnejad]

Dear users,
I am trying to make TiO2 nanotube from (101) monolayer as well as (001) one.
I did the following steps to make TiO2 nanotube from (101) monolayer.
1- File ---> add ---> from database ---> Anatase
2- Bulk tools ---> supercell ---> conventional ---> transform
3- Builders ---> surface (Cleave) ---> h=1, k=0, l=1 ---> nothing changed ---> non periodic and normal (thickness=1 layer, top vaccum=0 layer) ---> finish
* the periodic and normal (electrode) is disabled.
4- Bulk tools ---> repeat ---> A=10, B=1, C=1
5- Bulk tools ---> swap axes ---> A<--->B ---> X<--->Y
6- Bulk tools ---> swap axes ---> C<--->A ---> Z<--->X
7- Bulk tools ---> lattice parameters ---> put the x value greater than y value
8- Coordinate tools ---> center ---> apply
9- Coordinate tools ---> Tube wrapper
10- Bulk tools ---> repeat ---> A=1, B=1, C=3
However, the output is different from those in the papers.
In the case of step 4 as I changed (A=1, B=10, C=1), I ignored step 5 and just did step 6.
I also followed the manual and those posted before, still I have problem.
Any comments would be appreciated.

[Jess Wellendorff]

I don't know what the literature structures look like, but here is how I would create the TiO2(101) nanotube. The basic method is this:
1) create TiO2(101) monolayer similar to the carbon monolayer in this tutorial: http://docs.quantumwise.com/tutorials/exploring_graphene/exploring_graphene.html#build-a-graphene-sheet.
2) Use the Tube Wrapper tool to create the nanotube, just like in the tutorial.

More details:
1):
- add anatase bulk from the Database.
- Bulk Tools --> Supercell --> Body-Centered Orthorhombic.
- Builders -> Surface (cleave) --> create (101) surface [non-periodic and normal (slab)]
- Bulk Tools --> Repeat 10x along A
- Bulk Tools --> Swap Axes --> A to B ; X to Y; C to A ; Z to X.
- Bulk Tools --> Lattice Parameters --> increase the A vector length to at least that of B, e.g. 50 Å.
- Coordinate Tools --> Center
The monolayer sheet should now be ready for the tube wrapper.
2):
- Coordinate Tools --> Tube Wrapper --> 360 degrees and Helical rise 0.0 Å.
- Bulk Tools --> Lattice Parameters --> Set the A and B vector lengths to identical values.
- Coordinate Tools --> Center
See attached PNG.

[Anders Blom]

That is not correct

I have a better suggestion - see picture and final structure as Python script.
I'll write up the recipe here tomorrow - suspense

[Anders Blom]

Here is the receipe

1. Insert anatase from the database
2. Use Bulk tools>Supercell to turn it into a simple tetragonal cell
3. Cleave this 101. Note that it's not possible to make an "electrode-like" surface cell, but that's ok since you only need a monolayer. To get that (easiest), increase the "Thickness" to 2.5 layers.
4. After cleaving, make sure you view the structure down the X axis (so, look at the YZ plane). The bottom layers, as indicated in the attached picture, form the monolayer we are looking for (at least if I take inspiration from http://dx.doi.org/10.1002/pssb.200540026)
5. Delete the other atoms (not those highlighted, but all those above).
6. Now you have a structure that is periodic in B - this will form the tube circumference, so you can repeat it in B as many times as you want, to get a larger tube diameter
7. It's also periodic in A, this will be the tube axis. Now, the Tube wrapper tool wants this axis to be Z, so use the Swap Axis tool to swap Z<>X and C<>A (you must do both).
8. Change the A lattice vector to be about the same as B
9. Center the atoms in all directions
10. Use the Tube wrapper!

[abbasnejad]

Dear Anders Blom,
Thank you so much!
That is working well.
Just two questions:
1- How should the axes be oriented in the case of (n,m) nanotubes?
2- Is there any standard to select the appropriate atoms for wrapping and making nanotube?
Again thank you!
Regards,
Mohaddeseh