CNT DOS

[fedawy]

Dear Sir
the armchair (5,5) carbon nanotube exhibits a metalic behavior i.e (finite value of charge carriers in the DOS at the fermi level) but when i run it on ATK i found that DOS = zero around the fermi levelas shown in attached figure.why is that? 

[Anders Blom]

The DOS also requires a specification of k-point sampling. The default - which you used - is (1,1,1), so you only get the Gamma point DOS.

If you instead set 200 (or better 400 or 500) points along C, you get a much more proper picture, however it's hard to completely avoid a small artificial "band gap" since there is a band crossing right at the Fermi level.

[fedawy]

Dear Sir
thanks for help. but i want ask about the unit of the DOS (i guess it must be per eV per unit volume). why the DOS in the attached figure is only per eV?

[Anders Blom]

The normalization is such that if you integrate the DOS over energy (weighted by the Fermi function), the results equals the number of electrons in the unit cell.