Author Topic: Band Structure and Density of States  (Read 128 times)

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Offline paramjot

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Band Structure and Density of States
« on: March 19, 2020, 20:49 »
I made a structure of doped graphene and obtained its bandstructure and DOS. bandstructure is showing a bandgap of 0.45eV whereas at the same energy level the DOS chart showing some states instead of being value zero. I have all attached all the pictures. Can anybody tell me the reason?

Offline NW

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Re: Band Structure and Density of States
« Reply #1 on: March 20, 2020, 16:31 »
Hi,

It is better to obtain the band structure in other routes of Brillouin zone.

Offline Petr Khomyakov

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Re: Band Structure and Density of States
« Reply #2 on: March 23, 2020, 01:55 »
I made a structure of doped graphene and obtained its bandstructure and DOS. bandstructure is showing a bandgap of 0.45eV whereas at the same energy level the DOS chart showing some states instead of being value zero. I have all attached all the pictures. Can anybody tell me the reason?

Please post your python scripts and related log files for these calculations.

Offline paramjot

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Re: Band Structure and Density of States
« Reply #3 on: March 23, 2020, 23:16 »
all relevant files are attached

Offline Nayab Shiraz

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Re: Band Structure and Density of States
« Reply #4 on: March 23, 2020, 23:20 »
Hi
I am having a similar issue when I try to plot DOS for carbon nanotube (10,0) which is definitely semiconducting and has a bandgap. Bandstructure shows the bandgap but DOS shows a small value at fermi level. However when I plotted the same DOS in older version 13.8.1 this issue was not there. Now I have 2019 version and it gives this issue.

Offline paramjot

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Re: Band Structure and Density of States
« Reply #5 on: March 24, 2020, 20:31 »
Mr Petr can you please where I made a mistake?

Offline Petr Khomyakov

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Re: Band Structure and Density of States
« Reply #6 on: March 25, 2020, 16:39 »
You should try increasing k-point sampling for DOS calculation. I have attached a modified script that does that and also it includes 2 methods to compute DOS; for your system, you should decrease the Gaussian broadening such that the spectrum is not too broadened to close the gap.

I would also advise to use a more general analysis object (also available through GUI), https://docs.quantumatk.com/manual/Types/LocalDensityOfStates/LocalDensityOfStates.html, where you may change this broadening parameter and even set DOS method to tetrahedron method that does not require broadening parameter, but it requires a number of k-points, as used in the script enclosed.

Offline paramjot

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Re: Band Structure and Density of States
« Reply #7 on: March 25, 2020, 22:33 »
Thanks Sir! got positive result