[Pw_forum] Phonon calculations

[Lorenzo Paulatto]

On 12 November 2012 05:46, Elias Albert <physics-passion at live.com> wrote:

>  Dear all,
>
> I am doing some phonon calculations for an 8 atom supercell at q=0. I have
> therefore got 24 irreducible representations.. These representations are
> all of A symmetry.
>
> (1) Is there a possibility to calculate the phonon frequencies for each
> representation on its own (as I am interested in checking the value of
> first frequency) or does the code calculate all 24 representations in one
> go ?
>
> The frequencies are the (square root divided by some mass of the)
eigenvalues of the dynamical matrix: you need all the matrix before
diagonalizing it



> (2) Is there a way that the code just calculates the dynamical matrices
> WITHOUT diagnalizing them? and then use dynmat.x to do the diagonalization?
> If this is possible, does it reduce computation time?
>

ph.x computes the dynamical matrix and store it in the fildyn files, then
it also diagonalize it, but you can  ignore this part if you wish.


>
> Thanks
>

bests


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
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