[Pw_forum] TiO2 nanotube builder?

[Axel Kohlmeyer]

On Tue, Mar 17, 2015 at 5:44 PM, Amin Torabi <mtorabi at uwo.ca> wrote:
> Let's say I know the xyz coordinates of the atoms in bulk anatase TiO2, and
> I want to roll a sheet of it into a nanotube. How do I find the xyz
> coordinates of the nanotube?
>
> Can someone guide me through this?

this is a rather basic geometry/trigonometry exercise. basically you
have to solve the problem: how do you compute the x and y coordinate
of a point on a circle from its angle?

consider a suitably sized rectangular sheet, e.g. in the x-z plane. z
coordinates remain unchanged. the length of the rectangle in
x-direction L_x becomes the radius of the resulting tube and thus the
original x-coordinate now corresponds to an angle of 2*pi*x/L_x. from
that you can compute the x and y position on the circle. any
y-coordinates, i.e. from atoms that are above or below that base
plane, would then correspond to positions on a circle with larger or
smaller radius.

if this is still too confusing, search the web for examples of how
people construct carbon nanotube coordinates from a sheet of graphene.
its the same thing.

axel.

>
> Thanks!
>
> --
> **********************************
> Amin Torabi
> Ph.D. Candidate
> Department of Chemistry
> University of Western Ontario
> **********************************
>
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-- 
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.