2
$\begingroup$

I have XYZ data for a polymer that I simulated in LAMMPS. I need to generate the X-ray scattering intensity profile for my system. Does anyone know how to do this?

For reference, what I need is found in this paper, figure 9: (DOI 10.1021/ma9810565)

A sample dump file will be provided soon.

Thanks for your time.

Kind regards, Sean

Improve this question
$\endgroup$
12
  • 1
    $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Commented Jul 27 at 15:45
  • $\begingroup$ Welcome to our community! Please review this policy: mattermodeling.meta.stackexchange.com/q/393/5. Also, your post makes it look like you have asked ChatGPT to give you a script, then you have made 0 effort to figure out what it does or how it works, then you've asked us to verify for you whether or not "it's right", even though it's dozens of lines long. Is that fair? Have you even tried to run that script? I have deleted the ChatGPT part of your question for now. $\endgroup$
    – Nike Dattani - No Free Time
    Commented Jul 27 at 15:52
  • 1
    $\begingroup$ Perhaps the paper that you refer to gives some clues how the figure was obtained? $\endgroup$
    – marcin
    Commented Jul 27 at 16:08
  • $\begingroup$ The paper I reference does not explain it, no. Papers do a great job of giving a theoretical overview but usually are poor when reducing to practice. $\endgroup$
    – Marcus
    Commented Jul 27 at 17:42
  • 1
    $\begingroup$ Hi @NikeDattani-NoFreeTime, I just wanted to let you know that I saw your comments and I'm working on finding the equations that I need to use for calculating the scattering profile. $\endgroup$
    – Marcus
    Commented Jul 30 at 1:42

1 Answer 1

Reset to default
2
$\begingroup$

I checked the paper. It describes how figure 9 was computed by referring the reader to older papers:

the spherically symmetric powder pattern scatter-
ing intensity was calculated from the atom-atom pair
distribution functions. The functions for all of the atom
pairs are available elsewhere40. Standard techniques
as discussed by Wagner49 and invoked previously22,26
were used. The atomic scattering functions are from
Alexander50.

I didn't check these references, though. I assume the calculation is based on the Debye scattering formula. It's a standard way of computing a diffraction pattern from atomic positions, derived by P. Debye in 1915. This formula was derived by spherical averaging of the intensity – that's what "spherically symmetric" refers to.

The Debye formula is applied to a finite set of atoms. If you performed your simulation in periodic boundary conditions (PBC), you might need to first generate a larger system to capture longer-range interatomic distances. Then, instead of writing your own code, you might search what programs are already available. One of them is mine: https://github.com/wojdyr/debyer (written 15 years ago and not maintained anymore).

Improve this answer
$\endgroup$
2

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .