Dear Mark, Thanks for your reply.
> PDB format needs atom names but trjcat only knows how to read those > from a -s input file. There is no -s option (for tpr file) in the trjcat command. gmx_mpi trjcat -f 9_ms.pdb 19.pdb -o mix.pdb -settime -s md.tpr Error in user input: Invalid command-line options Unknown command-line option -s -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.