My Community

hi all,
1.I would like to ask how to use vasp for simulating nano tubes? also
2.is there any provision where i can specify an hypothetical structure by specifying all the atomic positions and do ab inition calculations on the structure?

1) simply give the atoms' coordinates in your POSCAR file and
an choose an appropriate k-mesh (KPOINTS), concerning the periodicity of the cell
2) I am sorry, I fear maybe I do not understand that question correctly....
-- the atomic positions are given in POSCAR
-- the geometry can be optimized by specifying the following tags in INCAR :
IBRION choose the ionic relaxation algorithm
NSW fix the maximum number of ionic steps of a job
EDIFFG breaking condition, this specifies your convergence criterium:
>0 total energy convergence ,
ISIF calculate the stress tensor to relax the ionic positions, and/or cell shape, and/or cell volume. please mind that PREC has to be set to Accurate to provide reliable stress tensors)
all these tags are discussed in detail in the online handbook
http://cms.mpi.univie.ac.at/CMSPage/main

Hi saurabhroy,

You will find what you need by reading:
http://ej.iop.org/links/q83/UCUv86Jph+U ... _1_125.pdf

where they explain how to simulate nanotubes.

Damien

the link is not accessable. Can you copy again? thanks

Hi,

You will find information in:

New Journal of Physics 5 (2003) 125.1–125.21 (http://www.njp.org/)


In fact, You are going to simulate like a tetragonal arrangement of nanotubes.
*
* * *
*
with a distance l between them. l needs to be large enough to avoid interaction.

So, your supercell is a cube and your basis set vectors are orthogonal.Your nanotube is placed around z-axis, so
norm(z)=length of your nanotube
norm(x)=norm(y)=diameter of nanotube + l

where (x,y,z is my basis set vectors)

I hope that my explication will help you

Damien