[gmx-users] Quick question: is TIP3P water model available in GROMOS54a7 force field?

[Wei-Tse Hsu]

Dear gmx users,
I prepared a topology using Open Forcefiled for my system. To make GROMACS
able to recognize the water molecules and the ions to be added, I need to
include itp files (such as tip3p.itp, spc.itp, ions.itp, etc.) in my
topology file (.top file). I was planning to use GROMOS54a7 with TIP3P
water model, so I add the following lines to my topology file:

; Include water topology
#include "gromos54a7.ff/tip3p.itp"

In gromos54a7.ff, there is indeed a tip3p.itp file. However, getting the
error of " Atomtype OWT3 not found", I later found that OWT3 was not
defined in ffnonbonded.itp. I also tried pdb2gmx command using other system
and chose gromos54a7 force field, but there is no option for selecting
TIP3P water model. Therefore, I wonder if TIP3P water model is actually not
available in GROMOS54a7 force field even if there is a tip3p.itp in
gromos54a7.ff. I might just use SPC water model instead, but I want to make
sure that my understanding is correct. Thank you!

Best,
Wei-Tse