[Wien] help required

arqum hashmi arqumhashmi at yahoo.com
Sun Apr 8 11:50:04 CEST 2012 

Thanks a lot Sir Xavier
 
i will do this consideration in my calculation and then tell you what happened.
 
anyway, i am very thankful to you.
Thanks and Regards
 

________________________________
 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 6:36 PM
Subject: Re: [Wien] help required
  

  
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>
>>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>
>>>To: A Mailing list for WIEN2k users <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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