How to simulated polystyrene using REACTER based on styrene using step growth mechanism ?
and how to write motemplate and set up edge atoms ?
This paper describes how to build a polystyrene model using REACTER assuming a step-growth polymerization: REACTER paper
Molecule templates are quite similar to data files, so you can typically use your favorite method for creating LAMMPS data files. Edge atoms are specified in the map file. Or, you can try using semi-automated tools such as LUNAR.
I highly suggest starting from the examples provided with LAMMPS in this directory: examples/PACKAGES/reaction
In this case, you can probably accomplish what you are asking for using the ‘tiny_polystyrene’ example with little modification.
The difference between step growth and chain growth ? the different is the concentration of initiator?
No. Your questions are no longer about how to use LAMMPS, and not appropriate for the LAMMPS category of this forum. You should refer to a textbook.