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

[Naveena P.S. <nav...@gm...>]

Hi

I followed the instructions in the document, but I am unable to modulate
the atom. It shows errors. Do you need the input files?

-naveena

On Fri 13 Feb 2026 at 08:16, Atsushi Togo <atz...@gm...> wrote:

> 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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>>>
>> _______________________________________________
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>>
>
>
> --
> Atsushi Togo
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