[Pw_forum] dos

[Stefano Baroni]

Cyrille: I totally agree with you, of course. What I was questioning  
is the relevance of taking averages of pdos centered around different  
centers, not the concept of PDOS itself
.
Concerning Berlusconi's brain, I think that's perfectly OK. What is  
probably not is the brain of those who find his behavior appropriate.

SB

On May 6, 2009, at 11:38 AM, Cyrille Barreteau wrote:

> Dear Stefano,
>
> Of course if you take the extreme case of the free electron gas, the
> local PDOS is obviously not more relevant
> than asking what it is s-like in Italy:-) (but maybe we could discover
> some interesting pertubation around Berlusconi brain:-)
> But in many cases  the local PDOS can be very useful to analyze DFT  
> results:
>   -local magnetism
>  -surface reactivity
> not to mention transport properties (STM images etc....)
>
> cyrille
>
> -- 
> ==================================================================
> Cyrille Barreteau  | phone : +33 (0)1 69 08 29 51
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> ==================================================================
>
>
>
>
>
> Stefano Baroni wrote:
>
>> I am still rather skeptical. If you apply your reasoning to the free
>> electron gas, it seems to me that you would obtain rather weird (to
>> say the least) results. I may be wong, and finally the choice on how
>> to analyze your data is yours. SB
>>
>> On May 5, 2009, at 9:26 AM, Gabriele Sclauzero wrote:
>>
>>>
>>> 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
>>>
>>>
>>> I agree with what you say, Stefano, about taking the expectation
>>> value of the angular
>>> momentum in a periodic system, but summing the PDOS of selected  
>>> atoms
>>> can lead to
>>> meaningful and sometimes very useful results, in some cases.
>>> I usually see the PDOS as an indicator of how much the Bloch states
>>> retain a kind of
>>> "atomic character" in the solid (so that in this case summing PDOS  
>>> of
>>> equivalent atoms is
>>> the more meaningful thing, as Lex pointed out), but also as a way to
>>> identify the symmetry
>>> of states.
>>> If you place a molecule, a nanowire or maybe even a surface with  
>>> slab
>>> geometry in a wise
>>> manner in your (super-)cell you can get many information from the
>>> PDOS (summed or not).
>>> Obviously, it does not make much sense to sum the s,p,d PDOS of all
>>> atoms in the system in
>>> general (but in some cases it may), so that's why you cannot find it
>>> directly in the
>>> output from projwfc.
>>> It's your task to select over which atoms you can do a sum (or an
>>> average) of the PDOS
>>> (and also placing the atoms in a smart way, first). I think you can
>>> write a script in
>>> awk/perl/whatever, or even a small fortran program, which reads PDOS
>>> from individual files
>>> associated to the selected atoms and sums the corresponding rows.
>>>
>>> Gabriele
>>>
>>>>
>>>> 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
>>>>
>>>>>
>> ---
>> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
>> Trieste
>> http://stefano.baroni.me [+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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