There may arise a need in modeling a near-infinite polymer chain, and one good approximation can be modeling of an infinite chain through PBC, while capturing just the monomer or an oligomer in a simulation cell. Here is a six-step procedure in building such a simulation cell.

Note: There had already been a post in this forum on a similar subject. Consider the present post an extension of the existing post.

Step 1. Build the monomer

Step 2. Build an empty cell. Be sure to make one of the cell dimensions comparable to the chain-length of the monomer

Step 3. Copy the monomer. Paste into the empty cell

Step 4. Center the monomer for convenience in viewing/editing

Step 5. Display two cells along the chain-length, then manually “polymerize”

Step 6. Clean