[QE-users] Calculate phonons only at the interface

[Paolo Giannozzi]

If your idea is to select a subset of atoms and compute the dynamical
matrix for that subset of atoms only, I do not think you wiell ever get
reasonable numbers.

Paolo

On Tue, Nov 5, 2019 at 7:06 PM thorgalg <thorgalg at poczta.onet.pl> wrote:

> Dear Christian,
>
> I spend the last two weeks testing this setting (nat_todo=16).
>
> My system contains more than 200 atom and was optimized
> until the forces on all the atoms were less than 0.02 eV/A.
> Then, I wanted to calculate the zero-point-energy (zpe) correction
> for the adsorbed molecule (benzene derivative) using ph.x. Unfortunately,
> I obtained a lot of imaginary frequencies (at the beginning of dynamical
> matrix in the ph.out file ):
>
>      freq (    1) =     -98.010682 [THz] =   -3269.284435 [cm-1]
>      freq (    2) =     -95.651863 [THz] =   -3190.602722 [cm-1]
>      freq (    3) =     -72.672472 [THz] =   -2424.092724 [cm-1]
>      freq (    4) =     -71.325508 [THz] =   -2379.162841 [cm-1]
>      freq (    5) =     -66.443681 [THz] =   -2216.322637 [cm-1]
>      freq (    6) =     -63.174512 [THz] =   -2107.274901 [cm-1]
>      freq (    7) =     -61.771254 [THz] =   -2060.467247 [cm-1]
>      freq (    8) =     -59.520061 [THz] =   -1985.375532 [cm-1]
> ...
> ...
>
> Then, when I wanted to calculate the dynamical matrix, the program
> (dynmat.x) stuck on attemption the asr calculation.
>
> ....
> Acoustic Sum Rule: || Z*(ASR) - Z*(orig)|| =    0.000000E+00
>
>
> The input file for dynmat.x is:
>
> &input
>  fildyn = 'benz_surf.dyn'
>  asr = 'zero-dim'
> /
>
> If this setting will work properly, it would be very helpful for all these
> QE
> users working on the theoretical catalysis.
>
> Best,
>
> Tomasz Krol
> Cracow University of Technology
>
> W dniu 2019-11-05 17:42:13 użytkownik Hari Paudyal <
> hpaudya1 at binghamton.edu> napisał:
>
> Hi Christian,
>
> nat_todo  can be used to choose the subset of atoms to be used in the
> linear response calculation. Please have a look if that is under your
> interest.
>
> Best,
> Hari Paudyal
> SUNY, Binghamton
>
> On Tue, Nov 5, 2019 at 11:26 AM Christian helman <
> christian.helman at gmail.com> wrote:
>
> Hi
> I just calculate an interface between two compounds. No problem and
> results are as expected.
> however I would like to calculate the phonons at the interface (even
> more electron -phonon coupling but let's start with just phonons).
> Since my unit cell is huge, my question is :
> is there any way to calculate the phonons "only at the interface" by
> allowing to move the interface atoms ?? something like "selective
> dynamics"
> Thanks in advance
>
> --
> Dr. Christian Helman
> Departamento de Neutrones y Reactores
> Centro Atómico Bariloche -CNEA
> Ezequiel Bustillos 9,500 Km - CP 8400
> San Carlos de Bariloche
> Provincia de Rio Negro, Argentina
> Tel:++54-294-444-5100 int 5308
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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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