write_coeff file file = name of data file to write out
Write a text format file with the currently defined force field coefficients in a way, that it can be read by LAMMPS with the include command. In combination with the nocoeff option of write_data this can be used to move the Coeffs sections from a data file into a separate file.
The write_coeff command is not yet fully implemented in two respects. First, some pair styles do not yet write their coefficient information into the coeff file. This means you will need to specify that information in your input script that reads the data file, via the pair_coeff command.