Running simulation of protein with Iron sulphur cluster

GROMACS version:2018
GROMACS modification: Yes/No
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Hello everyone,
I am new to GROMACS and I am trying to run a protein simulation with Iron-sulfur cluster as a ligand using Amber ff99sb forcefield. Can anyone help me regarding the generation of topology files of Iron Sulfur cluster? and how to define it to the force field? Thank you very much for your help.