[Pw_forum] Reg: How to know the mode name and due to which atom it is happening?

[Peram sreenivasa reddy]

Dear  Lima,

Thank you very much for your replay.  i will go through it and get back to
you.

Thank you.





On Tue, Apr 1, 2014 at 7:42 PM, Filipe Camargo Dalmatti Alves Lima <
flima at if.usp.br> wrote:

> It is because you did not finish all the steps to analyse the data.
>
> I got a similar problem before and I remember it is possible to obtain a
> file that has as the vectors of the modes that can be viewed in the
> xcrysden. Unfortunately I don't run simulations phonon simulations anymore,
> I couldn't remember everything I did in the past.
>
> I am pasting a manual section that explains it in details. (I also change
> the color to red the point I think might solve your issue.)
>
>
> 4.2 Calculation of interatomic force constants in real space
>
> First, dynamical matrices are calculated and saved for a suitable uniform
> grid of *q*-vectors (only those in the Irreducible Brillouin Zone of the
> crystal are needed). Although this can be done one *q*-vector at the
> time, a simpler procedure is to specify variable ldisp=.true. and to set
> variables nq1, nq2,nq3 to some suitable Monkhorst-Pack grid, that will be
> automatically generated, centered at [image: $ \bf q$] = 0 .
>
> Second, code q2r.x reads the dynamical matrices produced in the preceding
> step and Fourier-transform them, writing a file of Interatomic Force
> Constants in real space, up to a distance that depends on the size of the
> grid of *q*-vectors. Input documentation in the header of
> PHonon/PH/q2r.f90.
>
> *Program matdyn.x may be used to produce phonon modes and frequencies at
> any q using the Interatomic Force Constants file as input. Input
> documentation in the header of PHonon/PH/matdyn.f90.*
>
> See Example 02 for a complete calculation of phonon dispersions in AlAs.
>
> source:
> http://www.quantum-espresso.org/wp-content/uploads/Doc/ph_user_guide/node1.html
>
>
> I hope it will solve your issue.
>
>
> Best regards,
>
>
> Filipe
>
>
> On Tue, Apr 1, 2014 at 8:49 AM, Peram sreenivasa reddy <
> peramsreenivas at gmail.com> wrote:
>
>> Dear xirainbow,
>>
>> Thank you very much for your replay.
>>
>> In that case.dyn1 file also it is giving same only as in the case.ph.out
>> file.
>>
>> Please give me more clarification.
>>
>> Thanking you.
>>
>>
>>
>> On Tue, Apr 1, 2014 at 3:15 PM, xirainbow <nkxirainbow at gmail.com> wrote:
>>
>>> You can find the answer at the end of  *.dyn* files.
>>>
>>> On Mon, Mar 31, 2014 at 11:10 PM, Peram sreenivasa reddy
>>> <peramsreenivas at gmail.com> wrote:
>>> > Dear Pwscf,
>>> >
>>> > In my phonon calculations i got one imaginary mode in gamma to X
>>> direction.
>>> > I want to know which mode it is? and due to which atom it is happening?
>>> >
>>> > I checked the case.ph.out file. In this file it is given like below.
>>> >
>>> > Mode symmetry, O_h (m-3m)  point group:
>>> >   omega(  1 -  3) =        -16.6  [cm-1]   --> T_1u G_15  G_4- I
>>> >   omega(  4 -  6) =        122.3  [cm-1]   --> T_1u G_15  G_4- I
>>> >   omega(  7 -  9) =        145.0  [cm-1]   --> T_2g G_25' G_5+ R
>>> >   omega( 10 - 12) =        258.5  [cm-1]   --> T_1u G_15  G_4- I
>>> >
>>> > Here i am attaching the case.agr file
>>> >
>>> > Here all acoustic modes are given with same frequency. How can know
>>> that
>>> > particular mode name.
>>> >
>>> >
>>> >  My system is X2YZ type. How can i know this imaginary mode is due to
>>> which
>>> > atom. I plotted partial phonon density of states also. But all atoms
>>> are
>>> > giving same contribution in this acoustic mode region.
>>> >
>>> >  Thank you in advance.
>>> >
>>> >
>>> >
>>> > _______________________________________________
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>>>
>>>
>>>
>>> --
>>> ____________________________________
>>> Hui Wang
>>> School of physics, Henan University of Science and Technology, Henan,
>>> China
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
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>>>
>>
>>
>>
>>
>>
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>
>
>
> --
> _________________________________________
> Filipe Camargo Dalmatti Alves Lima
> PhD Student
> University of São Paulo, Physics Institute, Materials Physics Department,
> Nanomol Group, Brazil.
> Phones:    (11) 3091-6881  (USP)
>                 (11) 97408-2755 (Vivo)
>
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