[QE-users] [PW_forum] IFC file structure

[Paolo Giannozzi]

The three integer numbers label the distance between unit cells, not
between atoms.

Paolo

On Thu, Jun 6, 2019 at 2:15 AM Adrien Descamps <adrien.descamps59 at gmail.com>
wrote:

> Dear all,
>
> I am trying to calculate the phonon dispersion for Silicon. Thanks to the
> previous posts, I think I understand the structure of the output file and
> how to extract the interatomic force constant matrices.
> Since the Cartesian frame is given by the vectors (-1,0,1)a/2; (0,1,1)a/2
> and (-1,1,0)a/2, where can I find the IFC for the interaction between the
> two atoms in the unit cell, namely the interaction between atom at (0,0,0)
> and the 4 nearest neighbors at (1/4,1/4,1/4), (1/4,-1/4,-1/4),
> (-1/4,1/4,-1/4), (-1/4,-1/4,1/4)? I would expect to find it in the section
> 1 1 1 2 section but none of the position vector match the four first
> nearest neighbor, unless I making a mistake:
>
> 1   1   1   2
>    1   1   1  -6.76355682813E-02
>    2   1   1   7.83560937500E-05
>    3   1   1  -4.45195312500E-05
>    4   1   1   7.20209843750E-04
>    1   2   1  -6.76355682813E-02
>    2   2   1  -4.13570781250E-04
>    3   2   1  -4.13570781250E-04
>    4   2   1  -6.76355682813E-02
>    1   3   1  -4.63088953125E-03
>    2   3   1   1.34053593750E-04
>    3   3   1  -4.13570781250E-04
>    4   3   1   7.20209843750E-04
>    1   4   1  -4.63088953125E-03
>    2   4   1  -4.13570781250E-04
>    3   4   1  -4.45195312500E-05
>    4   4   1   3.78551718750E-04
>    1   1   2   7.83560937500E-05
>    2   1   2   1.17258593750E-04
>    3   1   2   3.07267343750E-04
>    4   1   2   7.20209843750E-04
>    1   2   2  -4.13570781250E-04
>    2   2   2   1.34053593750E-04
>    3   2   2  -4.63088953125E-03
>    4   2   2   7.20209843750E-04
>    1   3   2   1.34053593750E-04
>    2   3   2   1.34053593750E-04
>    3   3   2   3.07267343750E-04
>    4   3   2   3.07267343750E-04
>    1   4   2  -4.13570781250E-04
>    2   4   2   1.17258593750E-04
>    3   4   2   2.44567968750E-04
>    4   4   2   3.07267343750E-04
>    1   1   3  -4.45195312500E-05
>    2   1   3   3.07267343750E-04
>    3   1   3   3.78551718750E-04
>    4   1   3   2.42503593750E-04
>    1   2   3  -4.13570781250E-04
>    2   2   3  -4.63088953125E-03
>    3   2   3   3.78551718750E-04
>    4   2   3  -4.45195312500E-05
>    1   3   3  -4.13570781250E-04
>    2   3   3   3.07267343750E-04
>    3   3   3   2.44567968750E-04
>    4   3   3   1.17258593750E-04
>    1   4   3  -4.45195312500E-05
>    2   4   3   2.44567968750E-04
>    3   4   3   2.44567968750E-04
>    4   4   3  -4.45195312500E-05
>    1   1   4   7.20209843750E-04
>    2   1   4   7.20209843750E-04
>    3   1   4   2.42503593750E-04
>    4   1   4   2.42503593750E-04
>    1   2   4  -6.76355682813E-02
>    2   2   4   7.20209843750E-04
>    3   2   4  -4.45195312500E-05
>    4   2   4   7.83560937500E-05
>    1   3   4   7.20209843750E-04
>    2   3   4   3.07267343750E-04
>    3   3   4   1.17258593750E-04
>    4   3   4   7.83560937500E-05
>    1   4   4   3.78551718750E-04
>    2   4   4   3.07267343750E-04
>    3   4   4  -4.45195312500E-05
>    4   4   4   2.42503593750E-04
>
> Thank you very much,
>
> Best regards,
> Adrien Descamps
>
> Stanford Unversity, Aeronautics and Aerospace Engineering
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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