Band structure calculations of CNT - CNT junctions

[Brave]

Dear Quantumwise,

I have built a cnt-cnt junction by using the nanotube plugin. The gap between the CNTs is kept at 3.4 A.
I have tried to calculate the band structure for this device. However from the calculations I notice that the band structure is of the form of discrete lines, which is clearly not correct.
Can you please tell me where I went wrong?     

[zh]

The band structure calculations of such device is meaningless because the system is no periodicity in physics. The periodicity along directions A, B, and C is artificial due to the supercell model.
It is sure that the obtained  band structure of your system will form a discrete lines without  dispersion.

[Nordland]

This is technically a molecule, and therefore there is no dispersion as ZH says.

[Brave]

Thank you very much! I understand. So then to calculate the band structure of such junctions I could start from a graphite unit cell and modify the Brillouin routes?

[zh]

So then to calculate the band structure of such junctions I could start from a graphite unit cell and modify the Brillouin routes?

Attempt to calculate the band structure of such system is a waste of time.

It is meaningful to calculate the band structure of a CNT without vacuum gap along the tube axis.