Compute saed command - help.

Dear LAMMPS users,

I am currently engaged in a project in which I am trying to directly compare the results I obtain from MD 
simulations with the corresponding ones from electron diffraction experiments at a wide range of temperatures
using the USER-DIFFRACTION package and more specifically the compute saed command.

I went through the manual but I still have some open issues that need clarification.

My goal is to simulate the electron diffraction intensity of 
nanoparticles on a thin film as a function of the scattering vector 
(inverse Angstroms) for several temperatures averaged over few nanoseconds of simulation time.

In addition, I want to study the two following cases: (1) for all possible orientations 
relative to the electron beam, as when one measures powder diffraction 
and (2) for a specific direction of the electron beam (perpendicular to 
the thin film). I am fixing the relative orientation of the beam and 
sample through  the ''z1,z2,z3'' parameters. I will be grateful is 
someone more experienced on this type of calculations can verify that this is the way to do it.

In addition, the ''saed'' command produces ''vtk'' files. Is there a way 
to transform the enclosed information to Intensity versus A^-1?
It is a one-dimensional vector so there must be some way to transform it 
into 2D data (diffraction). Then we can simply
perform a radial integration.

Thank you in advance for your time and help.

Emmanuel N. Skountzos.

Hi Emmanuel-

In the current release, there is not an easy way to do the integration you’re requesting for SAED within LAMMPS. Though it is quite easy to do with XRD. I’ve been working on some updates offline that should give you different output formats (xyz, vtk, hist) and can send you that privately to test out.


Dear Shawn,

thank you for your quick and excellent response! It would be grateful if you could send me the updates that you mentioned.

As far as the first part of my question is concerned, do you believe that the way that I am following for the calculation of the

electron diffraction pattern is the correct one?



Στις 2018-03-19 13:15, Shawn Coleman έγραψε: