[gmx-users] incorporating itp files

[Senthil Kandasamy]

I want to practice running some simulations using GROMCACS before I jump 
into my specific system.
So I downloaded some pdb files from Peter Tielemen's  web site. I chose the 
dppc64.pdb file.
The first order of business is to generate a .gro file, I guess.
So I typed pdb2gmx -f dppc64.pdb using forcefield option 0.
The run created the topol.top and a conf.gro file. It also created a whole 
list of itp files.
I am confused here. My understanding is that the itp file is an input to a 
run providing topology information about a specific molecule.
In this case, DPPC is the molecule. But since DPPC seems to be included in 
ffgmx.rtp, I figured that I did not need any other itp for DPPC.
Where am I wrong?

Also, if I want to use the topology parameters from Peter's dppc.itp file, 
how do I do it?

If I sound naive, it is because I am...

Senthil