[Wien] The value of band gap from band structure is more less than DOS?

[taiiebeh molarooy]

  Dear wien users,
  Hi, I have calculated electronic structure of CNT, but there is any problem with value of band gap.
  The value of band gap from band structure is less than DOS. For example bad gap of CNT(10-0) from band structure is calculated about 0.35 eV while it is 0.9 eV from DOS. And also for CNT(16-0) with 64 atom, it is about 0.5 eV while it is 1.2 eV from DOS. 
  Do you know why the value of band gap is different?
   
  Another problem is that we are expected that value of band gap must be decreased by increasing diameter of CNT, while my results is inverse!
  Do you know why are these problems?
   
  Thank you very much in advance.
  Yours sincerely,
  Tayebeh.

       
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