The quality of the results obtained in calculations with the hybrid QM/MM method IMOMM on systems where the heme group is partitioned in QM and MM regions is evaluated through the performance of calculations on the 4-coordinate [Fe(P)] (P = porphyrin), the 5-coordinate [Fe(P)(1 - (Me)Im)] (Im = imidazole) and the 6-coordinate [Fe(P)(1 - (Me)Im)(O2)] systems. The results are compared with those obtained from much more expensive pure quantum mechanics calculations on model systems. Three different properties are analyzed - namely, the optimized geometries, the binding energies of the axial ligands to the heme group, and the energy cost of the biochemically relevant out-of-plane displacement of the iron atom. Agreement is especially good in the case of optimized geometries and energy cost of out-of-plane displacements, with larger discrepancies in the case of binding energies. © 2000 John Wiley & Sons, Inc.
|Journal||Journal of Computational Chemistry|
|Publication status||Published - 1 Jan 2000|
- Bioinorganic chemistry
- Heme group
- Hybrid QM/MM methods
- IMOMM method
- Iron porphyrin complexes