[Pw_forum] dos

[Lex Kemper]

Hi Jonas,

First, I don't know if a quantity such as the 'p' character of a system
is a useful thing to know, unless all the atoms are the same. If you
want to do so anyway, try familiarizing yourself with 'awk'. It's a very
useful utility for parsing text files.

Lex Kemper
University of Florida

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)
>>>> _______________________________________________
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>>>>
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>>>
>>>
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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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