How to partition a large cluster again?

OVITO General questions
1

Hello.
I have used the ClusterAnalysisModifier with the cutoff radius method to partition particles into clusters. The image below shows one of the clusters I obtained.
connect_cluster

I have noticed that this large cluster appears to be a connection between two subclusters, and the connection is quite “thin”.

Could you please advise me on how to partition this large cluster into subclusters based on its shape in OVITO, so that each subcluster no longer resembles a dumbbell shape? I understand that this may be an ill-defined problem, but I would appreciate any insights or suggestions.
Thank you in advance.

2

Hello,

I agree that this is a challenging issue. I recommend employing a method similar to erosion to remove the “bridge” connecting the clusters. Here’s the algorithm I suggest:

  1. Use the ‘construct surface mesh’ modifier to select particles on the surface of the cluster.
  2. Invert the selection to select all interior atoms.
  3. Apply ‘cluster analysis’ to the selected atoms only.
  4. If you end up with two or more clusters, jump to step 6.
  5. Erode the cluster:
    5.1 Invert the selection to select surface atoms.
    5.2 Expand the selection using the ‘expand selection’ modifier.
    5.3 Invert the selection again to identify interior atoms.
    5.4 Jump to step 3.
  6. Done

Now, you will have the labeled interior atoms for each cluster. The next step is to assign any surface atoms that were not selected during the process to their respective clusters. I recommend using the distance to the center of mass of each new cluster as the criterion for this assignment.