[Wien] help required

Sun Apr 8 09:43:47 CEST 2012

Dear Dr. Gerhard,
yes i put correct fermi energy for spaghetti.
DOS is zero at Fermi energy.
but band structure shows conducting behaviour. i don't know what is the problem with band structure.
if you give me any suggestion then i will be very thankful to you.

Best Regards
Arqum hashmi

________________________________
 From: "Fecher, Gerhard" <fecher at uni-mainz.de>
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at> 
Sent: Sunday, April 8, 2012 4:33 PM
Subject: Re: [Wien] help required

did you give the correct Fermi energy for spaghetti ?
did you check e.g. case.scf or shorter case.scf2 whether it reports an insulator behavior and a band gap ?
is your DOS Zero or only very small at the Fermi energy ?

Ciao
Gerhard

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]&quot; im Auftrag von &quot;arqum hashmi [arqumhashmi at yahoo.com]
Gesendet: Samstag, 7. April 2012 15:29
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] help required

Thanks a lot sir Xavier,
Before this i also thinked about this that  i don't have denser k mesh thats why i didn't get correct results.
yeah thats why i am saying to you that band structure giving very unnatural behaviour.  Sorry not ferromagnetic you can say that conductor behaviour because band lines crossing fermi level.
opposite behaviour means DOS showing bandgap but band structure showing conducting behaviour.

how can i check the convergency of my DOS calculation.

i am really worried about this.
Best Regards
Arqum Hashmi

From: Rocquefelte <Xavier.Rocquefelte at cnrs-imn.fr>
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
Sent: Saturday, April 7, 2012 8:48 PM
Subject: Re: [Wien] help required

I have difficulties to follow your arguments. In your first email you have mentioned that you did non spin polarized calculations, and now you are speaking about ferromagnetic character at M point!

In addition, I do not understand the following line: "DOS and band structre showing totally opposite behaviour".

My feeling remains the same and particularly in the present case. You are looking at graphene, a 2D system for which the band dispersion is large.
You must see Van't Hoff singularities in the DOS and you need to have a dense k-mesh to have a well-converged DOS.
Did you check the convergency of your DOS calculation but using denser k-meshes?

Regards

Xavier

On 04/07/2012 12:45 PM, arqum hashmi wrote:
Thanks Sir Xavier,
but the problem is this that both DOS and band structre showing totally opposite behaviour.
my system is graphene with some doping of Boron nitride.
DOS is good as we expect but band structure shows really strange behaviour. graphene  has zero bandgap in brillioun zone at K point and when i used graphene with BN, we obtain some ferromagnetic at M point when we plot band structure.

i don't know whats wrong with band structure.

Best Regrads
Arqum Hashmi

From: Rocquefelte <Xavier.Rocquefelte at cnrs-imn.fr><mailto:Xavier.Rocquefelte at cnrs-imn.fr>
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at><mailto:wien at zeus.theochem.tuwien.ac.at>
Sent: Saturday, April 7, 2012 7:02 PM
Subject: Re: [Wien] help required

The band gap estimated from the DOS is always larger than the one extracted from the band structure (which is more accurate).
To estimate the fundamental band gap you should consider the one deduced from the band structure.

The difference you observed is certainly due to the existence of a broad band which has a very low density near the Fermi energy. As a consequence, you can have the feeling that you have a gap by looking at the DOS.

Could you give more details about your calculations ? Which system ? The value of the band gap from the DOS ?

Regards

Xavier

On 04/07/2012 07:41 AM, arqum hashmi wrote:
Dear Wien2k Users

I am doing non spin polarized calculation. In this calculation, DOS and Band structure are not consistent with each other. DOS shows that it has some band gap but in band structure it shows that it is metallic. I don't know what is the problem in this and why DOS and Band structure is inconsistent with each other.
i expect that DOS is correct but something is wrong with band structure.
If any one of you give any suggestion that how i can solve this problem. I will be very thankful to you.

Best Regards
Arqum Hashmi

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