[gmx-users] charmm36M generated topology conversion to GROMOS54A7 ff

[Yogesh Sharma]

hi users,
I generated ligand topology containing complex metals using ATB server,
developed using GROMOS54A7 modified  forcefield. Then i used Charmm gui for
protein embedding in lipid bilayer followed by catenation of both .gro
files.  System was solvated but during ion addition it couldnot recognize
ligand metal atoms probably because of unmodified charmm 36m which doesnt
have parameters for metals. I want to use ATB generated modified gromos54A7
instead. How can I generate gromac topology for the combined system so that
i could use that with  modified forcefield?