Re: [Phonopy-users] Need help to used modulation command

[Atsushi T. <atz...@gm...>]

Hi,

Information is too little to see the issue. So it is difficult to answer.

> I found your youtube videos

I think those are not my youtube videos.

Togo


On Fri, Feb 13, 2026 at 1:22 AM Naveena P.Sivam <nav...@gm...>
wrote:

> Hello
> I am trying to do atomic modulation (atomic displacement) with respect to
> the normal mode at the specific q point. I tried to use this command line:
> phonopy --qe --modulation 2 2 1, 0.000000000   0.433012702   0.000000000 1
> 0.03 0 -c TiS2_primitive_scf.in --dim 2 2 1 -v.
>
> But it provides error like this:
>
> phonopy --qe --modulation 2 2 1, 0.000000000   0.433012702   0.000000000 1
> 0.03 0 -c TiS2_primitive_scf.in --dim 2 2 1 -v
>         _
>   _ __ | |__   ___  _ __   ___   _ __  _   _
>  | '_ \| '_ \ / _ \| '_ \ / _ \ | '_ \| | | |
>  | |_) | | | | (_) | | | | (_) || |_) | |_| |
>  | .__/|_| |_|\___/|_| |_|\___(_) .__/ \__, |
>  |_|                            |_|    |___/
>                                       2.47.1
>
> -------------------------[time 2026-02-06
> 16:53:41]-------------------------
> Compiled with OpenMP support (max 8 threads).
> Python version 3.11.11
> Spglib version 2.7.0
>
> Calculator interface: qe
> Crystal structure was read from "TiS2_primitive_scf.in".
> Unit of length: au
> Modulation mode
> Settings:
>   Supercell: [2 2 1]
> Spacegroup: P-3m1 (164)
> Number of symmetry operations in supercell: 48
> ------------------------------ primitive cell
> ------------------------------
> Lattice vectors:
>   a    6.460973493253429    0.000000000000000    0.000000000000000
>   b   -3.230486746626715    5.595367178253872    0.000000000000000
>   c    0.000000000000000    0.000000000000000   34.015070466894429
> Atomic positions (fractional):
>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867
>    *2 S   0.66666700000000  0.33333300000000  0.57891028530000  32.065
>     3 S   0.33333300000000  0.66666700000000  0.42108971470000  32.065
> -------------------------------- unit cell
> ---------------------------------
> Lattice vectors:
>   a    6.460973493253429    0.000000000000000    0.000000000000000
>   b   -3.230486746626715    5.595367178253872    0.000000000000000
>   c    0.000000000000000    0.000000000000000   34.015070466894429
> Atomic positions (fractional):
>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>    *2 S   0.66666700000000  0.33333300000000  0.57891028530000  32.065 > 2
>     3 S   0.33333300000000  0.66666700000000  0.42108971470000  32.065 > 3
> -------------------------------- super cell
> --------------------------------
> Lattice vectors:
>   a   12.921946986506859    0.000000000000000    0.000000000000000
>   b   -6.460973493253429   11.190734356507743    0.000000000000000
>   c    0.000000000000000    0.000000000000000   34.015070466894429
> Atomic positions (fractional):
>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>     2 Ti  0.50000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>     3 Ti  0.00000000000000  0.50000000000000  0.50000000000000  47.867 > 1
>     4 Ti  0.50000000000000  0.50000000000000  0.50000000000000  47.867 > 1
>    *5 S   0.33333350000000  0.16666650000000  0.57891028530000  32.065 > 2
>     6 S   0.83333350000000  0.16666650000000  0.57891028530000  32.065 > 2
>     7 S   0.33333350000000  0.66666650000000  0.57891028530000  32.065 > 2
>     8 S   0.83333350000000  0.66666650000000  0.57891028530000  32.065 > 2
>     9 S   0.16666650000000  0.33333350000000  0.42108971470000  32.065 > 3
>    10 S   0.66666650000000  0.33333350000000  0.42108971470000  32.065 > 3
>    11 S   0.16666650000000  0.83333350000000  0.42108971470000  32.065 > 3
>    12 S   0.66666650000000  0.83333350000000  0.42108971470000  32.065 > 3
>
> ----------------------------------------------------------------------------
>   ___ _ __ _ __ ___  _ __
>  / _ \ '__| '__/ _ \| '__|
> |  __/ |  | | | (_) | |
>  \___|_|  |_|  \___/|_|.
>
> Also, it creates modulation.conf which contains:
> DIM = 2 2 1
> MODULATION = 2 2 1, 0 0.433012702 0 1 0.03 0.
>
> Also, I found this idea from:
> https://phonopy.github.io/phonopy/setting-tags.html.
>
> Just today I started to use this package and I found your youtube videos
> discussing how to use phonopy with qe. So I thought I could ask for some
> help. kindly help me if you have any ideas.
>
> with regards
> Naveena P.
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>


-- 
Atsushi Togo