FFT of a data set

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1

Dear all,

I got stuck at some point in doing FFT of a data set. I have the data
of MSD of a system of particles which I have generated by 'compute msd'
command in LAMMPS.
Now I want to transform it to the Fourier domain. So, is it possible in
LAMMPS frame work or do I need to write my own code to post process it?

I will be extremely thankful if you can provide any sorts of ideas.

Thanking you,

Best,

2

Afaik, there's no LAMMPS command to do this. You could write your own code (Python's scipy has a nice FFT interface). xmgrace can also calculate them for you.

3

Dear all,

I got stuck at some point in doing FFT of a data set. I have the data
of MSD of a system of particles which I have generated by 'compute msd'
command in LAMMPS.
Now I want to transform it to the Fourier domain. So, is it possible in
LAMMPS frame work or do I need to write my own code to post process it?

there is no direct way to do it without some programming.

LAMMPS includes an FFT wrapper, but that is for parallel FFTs of
distributed 3D grids.

you *could* include the kissfft.h header from the KSPACE package,
which provides a 1D fft, which is a stripped down version of the
kissfft package from here: http://kissfft.sourceforge.net/

an option to do this without programming would be to use xmgrace or
with minimal programming by using some scripting language like python,
matlab or similar.

axel.