Reference: Shahrokh, K;  Orendt, A; Yost, G. and Cheatham III, T. E.
           "Quantum mechanically derived AMBER-compatible heme parameters for 
            various states on the cytochrome P450 catalytic cycle"
            J. Comp. Chem. (2011)

Supporting Material Tripos MOL2 format coordinate files for F-HM model B3LYP/LACVP gas-phase optimizations and RED-III derived atomic partial charges, and AMBER parameter files. 

For each of the heme states:
  (1) penta-coordinate ferric high-spin (IC6) 
  (2) dioxygen bound (DIOXY)  
  (3) Compound I (CPDI)
There are three files provided:
  (a) For the protoporphyrin macrocycle and iron (HEM.mol2), 
  (b) For the proximal cysteine ligand (CYP.mol2),  
  (c) AN AMBER parameter (*.frcmod) file.

NOTES: These also require that a protein force field (e.g. ff14SB) and GAFF parameters be loaded as well.
