Alternatives to the Standard Molecular Mechanics Force Fields

Alternatives to the Standard Molecular Mechanics Force Fields 

Generic authenticity and transferability are not virtues of the ionic models. Virtually all inorganic chemists would chafe at the notion that metal-ligand interactions can be attributed to electrostatic interactions alone. For example, ionic interactions cannot describe the binding of N2 or O2 to metal complexes ionic models cannot lead to the square planar structure observed for PtCl4 a purely ionic binding model is not in concert with the observation 

Although ligands are free to associate and dissociate from the metal, more terms must be added to correctly describe the molecular shape. These directional terms analyze the first ligand shell at the metal the energies appar- 

Clearly, the YETI force field is a very complicated approach to solving equally complicated problems. As such, it illustrates well the problems that must be addressed in inorganic modeling that simply do not occur in organic modeling. The primary problem addressed in Vendani s work is the variable coordination number of Zn and Co in carbonic anhydrase. The YETI program obviates some of these problems, but it is not apparent that the solution can be transferred to other metal systems. Nonetheless, useful results are obtained for the metalloenzymes and model systems for which the method was developed. 

Points-on-an-Equipotential-Surface Model Metal clusters display features that are difficult to model with MM force fields. A particularly vexing problem is the dynamic behavior of carbonyl (CO) ligands. Carbonyl ligands 

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