[Pw_forum] Phonon branch enumeration

[Jeffrey Mullen]

Thanks for the recommendation. I have performed the calculation with the
iverbosity set to 1. It will take me a while to parse it and understand
the output, but if I can figure out the relationships, I will attempt to
code the ordering into the application.

Cheers
Jeff Mullen
North Carolina State University


Dal Corso Andrea wrote:

>
>It is an interesting idea. I think it is possible to make the 
>symmetry classification of the displacements patterns with the same 
>routine that makes the symmetry classification of the eigenvectors 
>of the dynamical matrix. Presently, this is not done. You can  
>code this feature yourself or just use iverbosity=1. With this option
>the code writes the displacement patterns and you can   
>check their symmetry.  
>
>Andrea
>
>
>
>  
>
>>Cheers
>>Jeff
>>
>>
>>
>>e kb wrote:
>>
>>    
>>
>>>Dear Jeff,
>>>I am definitely not an expert on the topic but I'd like to understand
>>>your question better.
>>>
>>>    Mode symmetry, D_6h(6/mmm) point group:
>>>
>>>    omega(  1 -  1) =        -37.4  [cm-1]   --> A_2u            I
>>>    omega(  2 -  3) =        -33.9  [cm-1]   --> E_1u            I
>>>    omega(  4 -  4) =        863.3  [cm-1]   --> B_2g
>>>    omega(  5 -  6) =       1336.0  [cm-1]   --> E_2g
>>>
>>>So you have the irr. representations and the values for omega (values
>>>are printed with higher precision in the previous part after
>>>diagonalization as you reported). What exactly do you want to know
>>>more (that you cannot check from a book on group theory) ?
>>>
>>>Emine Kucukbenli, grad. student, SISSA, Italy.
>>>
>>>--- On *Tue, 3/10/09, Jeffrey Mullen /<jtmullen at ncsu.edu>/* wrote:
>>>
>>>    From: Jeffrey Mullen <jtmullen at ncsu.edu>
>>>    Subject: [Pw_forum] Phonon branch enumeration
>>>    To: pw_forum at pwscf.org
>>>    Date: Tuesday, March 10, 2009, 2:34 AM
>>>
>>>Greetings
>>>
>>>I am testing electron-phonon interaction calculations with graphene and
>>>have encountered a problem enumerating the resulting phonon branches.
>>>When I run the ph.x calculation at the q(0 0 0), the code calculates 4
>>>representations:
>>>
>>>    Representation #  1 modes #   1  2
>>>    Representation #  2 mode #   3
>>>    Representation #  3 mode #   4
>>>    Representation #  4 modes #   5  6
>>>
>>>
>>>When the values for omega are calculated, the results are:
>>>
>>>**************************************************************************
>>>    omega( 1) =      -1.119851 [THz] =     -37.354451 [cm-1]
>>>    omega( 2) =      -1.016557 [THz] =     -33.908905
>>>[cm-1]
>>>    omega( 3) =      -1.016557 [THz] =     -33.908905 [cm-1]
>>>    omega( 4) =      25.882237 [THz] =     863.344237 [cm-1]
>>>    omega( 5) =      40.051667 [THz] =    1335.988701 [cm-1]
>>>    omega( 6) =      40.051667 [THz] =    1335.988701 [cm-1]
>>>**************************************************************************
>>>
>>>
>>>with the following mode symmetries:
>>>
>>>    Mode symmetry, D_6h(6/mmm) point group:
>>>
>>>    omega(  1 -  1) =        -37.4  [cm-1]   --> A_2u            I
>>>    omega(  2 -  3) =        -33.9  [cm-1]   --> E_1u            I
>>>    omega(  4 -  4) =        863.3  [cm-1]   --> B_2g
>>>    omega(  5 -  6) =       1336.0  [cm-1]   --> E_2g            R
>>>
>>>
>>>My question is one of ordering. How do I extract which omega(##)
>>>corresponds to which representation/mode?
>>>
>>>Thanks
>>>Jeff Mullen
>>>North Carolina State
>>>University
>>>
>>>_______________________________________________
>>>Pw_forum mailing list
>>>Pw_forum at pwscf.org
>>>http://www.democritos.it/mailman/listinfo/pw_forum
>>>         
>>>
>>>
>>>------------------------------------------------------------------------
>>>
>>>_______________________________________________
>>>Pw_forum mailing list
>>>Pw_forum at pwscf.org
>>>http://www.democritos.it/mailman/listinfo/pw_forum
>>> 
>>>
>>>      
>>>
>>_______________________________________________
>>Pw_forum mailing list
>>Pw_forum at pwscf.org
>>http://www.democritos.it/mailman/listinfo/pw_forum
>>    
>>