Hi, > trjconv -f a.xtc -o a_cluster.gro -e 0.001 -pbc cluster
You might want to use -dump to extract a specific frame, rather than using -e: trjconv -f a.xtc -o a_cluster.gro -pbc cluster -dump 0 Also, do mind that for a subsequent call to trjconv, using -pbc nojump and the extracted frame as reference structure, the difference between the dumped frame and the first in the trajectory should not be too large. Otherwise -pbc nojump produces garbled results. Cheers, Tsjerk -- Tsjerk A. Wassenaar, Ph.D. Computational Chemist Medicinal Chemist Neuropharmacologist -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/mailing_lists/users.php