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QuantumATK => General Questions and Answers => Topic started by: S. I. Mallick on July 2, 2015, 15:51

Title: Question on Band structure and DOS of CNT
Post by: S. I. Mallick on July 2, 2015, 15:51

I am new to Quantumwise.
I want to see Band-structure of CNT, which is infinitely long. Is it possible to see this here. if yes then how to set it?

And i have some problems with DOS plot of CNT. I did not get the plot as given in a paper. Can you please explain me how to set parameter to get accurate plot of DOS ?

Title: Re: Question on Band structure and DOS of CNT
Post by: zh on July 4, 2015, 06:10

First, you have to understand the physics meaning of periodic condition, infinite system, and band structures. For such knowledges, please read the textbook.

For your second question, please post more details of your problem, i.e., the reference you want to reproduce, the parameters used in your calculations, the results you have obtained. Otherwise, it is difficult or impossible to give useful suggestions to you.

Title: Re: Question on Band structure and DOS of CNT
Post by: S. I. Mallick on July 5, 2015, 10:41

thank you for your responce.
I was trying to get result as mention in the paper (URL: http://www.sciencedirect.com/science/article/pii/S0167931713000026#). But i got problem on DOS plot and confusion on band structure. The files are attached here.

result from paper: file name - paper.jpg
band-structure i get in extended huckel method: file name - cnt(6,0)_band.png
dos plot i get: file name -CNTdos.jpeg

Parameter I set for extended huckel method for simulation:

electron temperature: 600K
k point sampling: (1*1*100)
huckel basis set: cerda.carbon[graphite]

Band-structure points per segment: 30

DOS k point sampling: nA= 3, nB= 3, nC= 3

What should i do to get Dos plot as given in the paper? and to get band structure can i take one CNT unit cell in calculator?

Title: Re: Question on Band structure and DOS of CNT
Post by: zh on July 6, 2015, 13:09

From the band structure figures of yours and the reference, I could say that you have reproduced the EHT results in literature.  The discrepancy in the DOSs results might be because you used too few k points along the CNT axis direction. If the axis of CNT in your simulation is along the z direction, you might use 1 x 1 x 50, 1 x 1 x 100, or even more to do the DOS calculations. This will improve your DOS results.

Title: Re: Question on Band structure and DOS of CNT
Post by: S. I. Mallick on July 20, 2015, 12:00

thank you. i got the result.