Force Field parameters for ATP/ADP/GTP/GDP with OPLS?

GROMACS version: 2020
GROMACS modification: No

I’ve been running a number of simulations with OPLS using the LigParGen server from Jorgensen’s lab for ligands, but I’ve noticed that OPLS has separate papers on parameters for the common ADP/ATP/GTP/GDP molecules that may be more accurate. Unfortunately, I’ve not come across any GROMACS formatted versions of these molecules.

Before I start down the path of manually converting, I was wondering if anyone else has done this before or if anyone has a good way of converting CHARMM formatted param/top files (which are available from Jorgensen’s webpage) to gromacs itp (or ideally both itp formats and gromacs residue topology file entries).

Thanks in advance