[gmx-users] Problem with restrained MD

[Ivano Eberini]

Hi,
we are trying to perform a MD calculation for basic fatty acid binding protein
with oleate. We prepared .top and .gro files for this protein with oleic acid
and performed EM. After this run, when precompiling with grompp for
position-restrained MD (restrains were applied to system: protein + oleate, by
file posre.itp), we got a fatal error:
file "posre.itp" line 25
Atom index (21) in position_restraint out of bounds (1-20)

Does anybody have suggestions?
Thanks in advance.
Best wishes,
Ivano