[Pw_forum] dos

[Stefano Baroni]

... and pardon us if it took eight minutes to get three decent  
answers ...
Enjoy! Stefano

On May 4, 2009, at 5:55 PM, Stefano Baroni wrote:

> Jonas: I am afraid that what you want to obtain does not make much  
> sense. The angular character of any molecular (or Bloch) state  
> depends on the origin of your reference system. What is "s-like"  
> with respect to one point has an infinite number of angular  
> components with respect to a different point. Are you sure you want  
> to add "what is s-like in Iowa" with "what is s-like in Italy" ??? ;-)
> Stefano
>
> On May 4, 2009, at 5:51 PM, Jonas Baltrusaitis wrote:
>
>>
>> I just successfully calculated DOS and PDOS of a very large system.  
>> One thing that confuses me is the presence of s, p components to  
>> PDOS for every atom, but not summed (or averaged) s and p  
>> contribution of all system. I would be happy to find in my output  
>> total DOS, PDOS s character and PDOS p character. Is there a way to  
>> get that instead of contribution per every atom? Or how do I  
>> proceed to get s and p PDOS for all system by manually processing  
>> all of my 76 atoms PDOS outputs?..
>>
>> thanks
>>
>> Jonas Baltrusaitis
>> University of Iowa
>>
>>
>> --- On Mon, 5/4/09, Prasenjit Ghosh <prasenjit.jnc at gmail.com> wrote:
>>
>>> From: Prasenjit Ghosh <prasenjit.jnc at gmail.com>
>>> Subject: Re: [Pw_forum] dos
>>> To: jasius_1 at yahoo.com, "PWSCF Forum" <pw_forum at pwscf.org>
>>> Date: Monday, May 4, 2009, 12:04 AM
>>> Hi Jonas,
>>>
>>> For DOS calculations one needs to do an integration over
>>> the kpts in the
>>> Brillouin zone. So you need a very fine k-point mesh than
>>> necessary for a
>>> scf calculation. Moreover you need a large number of bands.
>>> Doing an scf
>>> calculation with such a fine k-point mesh and so many bands
>>> is very
>>> expensive. So you should first do an scf calculation with
>>> the min. no. of
>>> k-points and bands and then do a nscf calculation with a
>>> finer k-point and
>>> larger no. of bands. In the nscf step, the code does an
>>> interpolation for
>>> the extra bands and k-points and not a self-consistent
>>> calculation. This
>>> saves computational time.
>>>
>>> Hope this helps.
>>>
>>> Prasenjit.
>>>
>>> 2009/5/3 Jonas Baltrusaitis <jasius_1 at yahoo.com>
>>>
>>>>
>>>> Prasenjit,
>>>>
>>>> could you explain why both scf followed by nscf
>>> calculations are needed for
>>>> DOS calculations, as per example 8? If only scf
>>> density is needed for
>>>> further projection, why not to calculate only one?
>>>>
>>>> Jonas
>>>>
>>>>
>>>> --- On Sun, 5/3/09, Prasenjit Ghosh
>>> <prasenjit.jnc at gmail.com> wrote:
>>>>
>>>>> From: Prasenjit Ghosh
>>> <prasenjit.jnc at gmail.com>
>>>>> Subject: Re: [Pw_forum] dos
>>>>> To: "PWSCF Forum"
>>> <pw_forum at pwscf.org>
>>>>> Date: Sunday, May 3, 2009, 2:00 PM
>>>>> dear all user
>>>>>>
>>>>>
>>>>> Dear Yaldaa,
>>>>>
>>>>>
>>>>>> How can I project dos to molecular orbital?
>>>>>>
>>>>>
>>>>> There is a post-processing tool called projwfc.x
>>> which you
>>>>> can use to
>>>>> project dos to molecular orbital.
>>>>>
>>>>> what is the importance of nbnd in calculations
>>> for dos?
>>>>>>
>>>>> e
>>>>> "nbnd"  tells the code the no. of
>>> Kohn-Sham
>>>>> states it has to
>>>>> compute.....While computing the dos, one wants to
>>> plot the
>>>>> dos for both the
>>>>> occupied & unoccupied manifold, the no. of
>>> energy
>>>>> levels is read in by the
>>>>> dos.x from the output of your scf/nscf run. So
>>> while doing
>>>>> an scf/ nscf
>>>>> calculations you can control the total no. of
>>> states with
>>>>> the variable
>>>>> "nbnd".
>>>>> Depending on the type of occupation scheme you
>>> choose the
>>>>> value of nbnd is
>>>>> nelec/2 (fixed occupation)  or nelec/2+some extra
>>> bands
>>>>> (when you use
>>>>> smearing). If you want to plot the dos, usually
>>> you should
>>>>> add some extra
>>>>> levels using nbnd & do the scf or nscf
>>> calculations to
>>>>> get the unoccupied
>>>>> manifold.
>>>>>
>>>>> and for plottingdos or pdos, if the fermi energy
>>> is assumed
>>>>> to be zero
>>>>>> automatically by program?
>>>>>>
>>>>>
>>>>> No, you have to do the alignment yourself
>>>>>
>>>>> With regards,
>>>>>
>>>>> Prasenjit.
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> PRASENJIT GHOSH,
>>>>> POST-DOC,
>>>>> ROOM NO: 265, MAIN BUILDING,
>>>>> CM SECTION, ICTP,
>>>>> STRADA COSTERIA 11,
>>>>> TRIESTE, 34104,
>>>>> ITALY
>>>>> PHONE: +39 040 2240 369 (O)
>>>>>             +39 3807528672 (M)
>>>>> _______________________________________________
>>>>> Pw_forum mailing list
>>>>> Pw_forum at pwscf.org
>>>>>
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>> -- 
>>> PRASENJIT GHOSH,
>>> POST-DOC,
>>> ROOM NO: 265, MAIN BUILDING,
>>> CM SECTION, ICTP,
>>> STRADA COSTERIA 11,
>>> TRIESTE, 34104,
>>> ITALY
>>> PHONE: +39 040 2240 369 (O)
>>>             +39 3807528672 (M)
>>
>>
>>
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>
> ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
> Trieste
> [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)
>
> La morale est une logique de l'action comme la logique est une  
> morale de la pensée - Jean Piaget
>
> Please, if possible, don't  send me MS Word or PowerPoint attachments
> Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html
>
>
>
>
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale  
de la pensée - Jean Piaget

Please, if possible, don't  send me MS Word or PowerPoint attachments
Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html




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