[gmx-users] megnesium -heme

[Lakshmi Padmavathi]

Dear gromacs users,
     you helped me many times , thank you very much for all of you.

i am doing simulation with a chlorophyll.
i took the parameters from the heme forcefield of ffG43b1.
is it correct?

how can i choose the parameters for the bond lenth and angle of megnisium 
instead of Iron.
for example.
N - Mg
N-MG -N
C-N-MG

thank you very much

sincerely,