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

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

Hi,

> How to perform this?

It is written in the documentation.

> if you need any additional input, let me know.

I need to reproduce your issue.

Togo

On Fri, Feb 13, 2026 at 1:59 PM Naveena P.Sivam <nav...@gm...>
wrote:

> Hi,
>
> I need help to perform atomic modulation with a specific q-point
> (pre-processing after DFPT calculation using QE)  using phonopy. MODULATION
> = (command). How to perform this?
>
> if you need any additional input, let me know.
>
> with regards
> Naveena
>
> On Fri, Feb 13, 2026 at 4:38 AM Atsushi Togo <atz...@gm...> wrote:
>
>> 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.
>>> _______________________________________________
>>> Phonopy-users mailing list
>>> Pho...@li...
>>> https://lists.sourceforge.net/lists/listinfo/phonopy-users
>>>
>>
>>
>> --
>> Atsushi Togo
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-- 
Atsushi Togo