[Wien] help required

[Rocquefelte]

Just one more comment. For hexagonal systems it is usually required to 
do not apply a shift for the k-mesh and to include the gamma point in 
the DOS calculation.
In your case, I will check the convergency of you DOS calculation with 
and without a shift of the k-mesh. It is highly probable that the band 
gap is only defined for high-symmetry k-points, explaining the 
difference between the DOS and the band structure (the latter one based 
on high-symmetry points).

Regards

Xavier


On 04/08/2012 09:45 AM, arqum hashmi wrote:
> Thanks Sir Xavier
> i will do it then tell you.
> 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:* Sunday, April 8, 2012 4:41 PM
> *Subject:* Re: [Wien] help required
>
> For the convergency of the DOS you simply have to plot the DOS for 
> different k-meshes (increasing progressively the number of k-points) 
> and when the DOS stops to evolve then you are converged.
>
> Regards
>
> Xavier
>
>
> On 04/07/2012 03:29 PM, arqum hashmi wrote:
>> 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> 
>> <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 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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