I am using ffG43a1. in hdb file, there is only amino acids relating to protein and no nucleic acid relating to dna. I post error message in previous mail. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20090831/94ed1f43/attachment.html>