I have what is probably a silly question about the colour coding modifier. I am using it to begin the analysis of my LAMMPS trajectory files by colour coding the potential energy per atom and entropy per atom. There is one thing that has caused some confusion in both myself and my supervisor. By default, when you bin a region of a histogram to then analyze with the colour coder, atoms that don't belong to that range take on the respective extremes of the colour map. Is there any way that I can remove the colour of atoms outside of the regions I am binning?


1 Answer 1


I have this sorted out now. I managed to miss that there is the expression select modifier. All of that information can be found here. All that is needed is a little boolean algebra and any other relevant modifiers to the parameters you are trying to constrain for colour coding. As an example, I will use my own use for the modifier:

In my case, I have a trajectory in which I want to look at the coordination number of oxygen in an ice structure. What I can do is the following:

  • Add the expression select modifier and give it the condition "Coordination $\le$ 4"
  • To see everything with coordination larger than 4, I can add the invert select modifier
  • Lastly, to get rid of the atoms I don't want, I can add the delete selected modifier

And from there I can colour code and see everything I want. There are a lot of different selection conditions that you can apply, all of which are mentioned in the Ovito documentation link I provided. But the general premise is that it all uses Boolean algebra that is very similar to the syntax used in C languages

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    $\begingroup$ Thanks so much for coming back and writing a self-answer! It can help future visitors who have the same problem. At the moment it's a "link-only" answer, so if you could please expand your answer by including the substance of that link into your answer, rather than directing users to external resources, that would be very much appreciated! $\endgroup$ Commented May 22 at 23:01

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