[gmx-users] gromos96 forcefield

[Thomas Schlesier]

dear all,
till now i simulated with the gromos87 forcefield, but now i want to
change it.
i have two small molecules which consist of a short alkane chain and
then an urea-group.

i built my molecules with spartan and saved them as .pdb then i tried
pdb2gmx, but this failed:
Fatal error:
Residue 'UNK' not found in residue topology database
but i have no idea how i should name the residues so that they are found
in the database.
then i tried pdb2gmx with my .gro file (which i get from prodrg with the
.pdb file), but here the same problem occured.

the other thing that i tried was to make the files with the beta version
of prodrg. i get the .gro/.g96 and .itp files but they look the same
like the files for the gromos87 forcefield (different values but the
same format).
i used editconf on the .g96 file but it doesn't really work, the new 
.g96 file looks like:

TITLE

END
POSITION
END
BOX
   10.000000000   10.000000000   10.000000000
END

from that and the gromacs-user manual i get the idea that .gro and .96
files use different formats, but i don't really know how the format for
.g96 looks like (i looked for a user manual for gromos96, but didn't
found one for free).

so the question is:
1) is there a way to translate the gromos87 files to gromos96?
or
2) what should i do with the files form prodrg beta that they work?

thanks for an answer
thomas