Extensible Systematic Force Field

A. M. Schneider and P. Behrens, Chem. Mater., 10,679 (1998). Molecular Mechanics Study on Organometallic Complexes in Crystalline Silica Matrixes Using the ESFF (Extensible Systematic Force Field). 

Shi, S., et al., An extensible and systematic force field, ESFF, for molecular modeling of organic, inorganic, and organometallic systems. J Comp Chem, 2003 24 1059. 

Extensive documentation of the accuracy of molecular mechanics calculations has been reported.For the most part, the discrepancies between experimental and calculated molecular geometries are within experimental error. Many of the systematic discrepancies in MM2, for example, have been documented. Some of the apparent errors can be associated with incorrect comparisons of bond lengths that are defined differently in various experimental and computational methods. The bond lengths have different numerical values because they are different physical quantities, rather than being real errors. Other problems have been attributed to a lack of accurate experimental data when the force field equations and parameters were formulated. 

The above internal coordinates and nonbonded interaction terms comprise the force field equations in molecular mechanics to calculate the potential energy of a molecular system. The basic form of empirical force fields has been varied as part of efforts to improve their treatment of various biological systems. Extensive work has been done on the systematic improvement of the both the form and the parameters used (35). However, this consensus form is common to AMBER (36), CHARMM (37), and CVFF (38), three popular classical empirical force fields. 

Morino and his co-workers established a systematic treatment for the calculation of mean amplitudes of vibration from harmonic force fields, based on the widely used Wilson GF matrix method, which is still the foundation for the majority of such calculations. The theory of such calculations has been developed considerably since, notably by Cyvin and coworkers. With the advent of modern computers, the calculation of mean amplitudes using these methods has become a routine procedure. The resultant extensive literature has been reviewed by Cyvin. ... 

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