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QuantumATK => General Questions and Answers => Topic started by: GJK on May 27, 2014, 10:12

Title: ZGNR Band gap and electron density-reg
Post by: GJK on May 27, 2014, 10:12

Dear Dr.Anders,

I have attached my files which I got for Band gap analysis of ZGNR with and without molecule attachement.

1.With perfect ZGNR(file BSori) I am geeting band crossing at Fermi level so noband gap.Am I right??

2.For the molecule adsorbed ZGNR I am getting a band structure(as attached(file BS).Does it have a band gap or not???

3.The electron density and iso surface of perfect ZGNR(hydrogen passivated) is attached.The electron density runs from 0(blue)-1(green)-2(red) and the iso surface is showing as -1(blue)-0(green)-1(red).From isosurface value I predict that my electron density is 1(Angstrom cube).Am I correct??

4.What actually the isosurface says about electron density (or) electron difference density etc???

Thanks in advance

Title: Re: ZGNR Band gap and electron density-reg
Post by: GJK on May 28, 2014, 16:13

Dear sir,

Kindly explain my query posted.

For ZGNR with a molecule I am getting a band crossing at the fermilvel(fig BSori).Does it have a band gap or not???

How to get the electron density value from the electron density file which is attached (ED.png).Actually the value runs from min=0,center=1 and max=2.The isosurface value(EDiso.png) runs from min= -1,center=0,Max=1.What is my electron density value???

Title: Re: ZGNR Band gap and electron density-reg
Post by: zh on May 29, 2014, 07:46

For ZGNR, it is more meaningful to perform the spin polarization calculations with the  spin for carbon atoms at one edge opposite to those in the other edge, because the antiferromangetic state of ZGNR is more stable than the ferromagnetic nonmagnetic ones.

Title: Re: ZGNR Band gap and electron density-reg
Post by: GJK on May 30, 2014, 10:19

Dear Mr.zh,

Thank you for the suggestions.I am trying with spin also parallely.

But kindly tell me for my system( file BS) does it have a band gap or not.

How to get the electron density value from the electron density file which is attached (ED.png).Actually the value runs from min=0,center=1 and max=2.The isosurface value(EDiso.png) runs from min= -1,center=0,Max=1.What is my electron density value???

Title: Re: ZGNR Band gap and electron density-reg
Post by: zh on June 1, 2014, 00:35

From your plot of band structure, it indicates that there is no band gap.



The isosurface plot shows the distribution of a quantity at a specific value. This value is an input and you have to specify it when you draw the isosurface plot.   

Title: Re: ZGNR Band gap and electron density-reg
Post by: GJK on June 3, 2014, 09:30

Quote from: zh on June  1, 2014, 00:35

From your plot of band structure, it indicates that there is no band gap.



The isosurface plot shows the distribution of a quantity at a specific value. This value is an input and you have to specify it when you draw the isosurface plot.   

ok then what is my electron density value???

Only if we know the electron density we can calculate the charge density by taking the difference.

Title: Re: ZGNR Band gap and electron density-reg
Post by: GJK on June 4, 2014, 13:58

Dear Mr.Zh,

What is my electron density value?