[DFTB-Plus-User] CNT(12,7) Density of States trouble

david at ufma.br david at ufma.br
Fri Mar 14 21:17:40 CET 2008

Dear colleague,

I have calculated the DOS for (12,7) carbon nanotubes using DFTB+.
We truely just have considered a fragment of a nanotube and the nanotubes ends
were filled by hydrogens atoms.
For this case in this approximation we are obtaining a conductor nanotube and
not a semiconductor as we hope.
On the other hand we have used the same strategy to calculate the
fragments of CNT(11,9) and CNT(13,5) again filling the nanotubes ends
valencies with hydrogens atoms and the calculations result were semiconductor as
we hope.
Can you help us to detect what is happening?

We are attaching the inputs, outputs and respective *.skf files and a figure of
the obtained DOS
in *.jpg format.

Really thanks,


What is limit for the number of atoms in a periodic structure like
a nanotube using dftb+? Is there a way to change this limit?
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