I am trying to simulate a bulk crystal, but the final structure split into pieces. I checked it step by step, and found that after reading the data file, the structure split, just the same as the final structure.
Any help or suggestion will be highly appreciate.
The structure is “split” in both cases, but in one case you don’t see it because the gap is where the box boundaries are. Visualize it with periodic replication of the principal box, and the gaps will reemerge.
This means that your box dimensions in the data file are incorrect.