[gmx-users] How can I add ffG43a1p force field to gromacs software?

[Mark Abraham]

Mitra Kheirabadi wrote:
> Dear Dr.Periole
>  
> I add ffG43a1p to FF.dat/ top and changed 11 to 12 on this file but 
> sorry again I did not appear. please help me.

The new forcefield files have to go to the same location as the old 
ones, in the subdirectory something like share/gromacs/top. Or 
preferably, you can copy the contents of that directory to somewhere 
else, do your fiddling there, and set the environment variable GMXLIB to 
point to that new directory every time you want to use this modified 
forcefield. When you don't want this forcefield, unset GMXLIB and you 
will get back your pristine GROMACS installation, and you can be 
confident you haven't broken things there!

Unless you have pre-built .itp files for the phosphorylated systems, it 
is likely you will need to define new residue types in an .rtp file. 
Copy and rename the ffG43a1 version, and modify to suit your planned 
residues. A sound knowledge of chapter 5 of the manual will be required.

Mark