[gmx-users] PTFE polymer chain

[luanadelorenzo at libero.it]

Hi 
I'm a new user of Gromacs and I want to construct a linear chain of  
polytetrafluoroethylene using the force field oplsaa.
I created  a work directory and I modified the rtp files by introducing 3
new residues corresponding to my starter of chain (TFEa), my internal
residue (TFEi), and my terminal residue (TFEb)(following the same procedure
descirbed by Justin for Polyethylene) I add these new three residue to the
residuetypes.dat as Other.
When I run pdb2gmx with the -ff option (for using my modified force field)
the message of error is the following:
Could not find force field '/home/user01/work/oplsaa.ff/' in current
directory, install tree or GMXDATA path.
If I use pdb2gmx without using the command -ff the error is always the same:
Fatal error:
Residue 'TFEa' not found in residue topology database
How can I solve this problem? Could someone help me?
Thanks!
Luana.