Merck molecular force fields

Inadequate availability of experimental data can considerably inhibit the development of improved energy functions for more accurate simulations of energetic, structural, and spectroscopic properties. This has led to the development of class II force fields such as CFF and the Merck Molecular Force Field (MMFF), which are both based primarily on quantum mechanical calculations of the energy surface. The purpose of MMFF, which has been developed by Thomas Halgren at Merck and Co., is to be able to handle all functional groups of interest in pharmaceutical design. 

Halgren T A 1996a. Merck Molecular Force Field I. Basis, Form, Scope, Parameterisation and Performance of MMFF94. Journal of Computational Chemistry 17 490-519. 

Halgren T A 1996b. Merck Molecular Force Field II MMEF94 van der Waals and Electrostatic Parameters for Intermolecular Interactions. Journal of Computational Chemistry 17 520-552. 

The Merck molecular force field (MMFF) is one of the more recently published force fields in the literature. It is a general-purpose method, particularly popular for organic molecules. MMFF94 was originally intended for molecular dynamics simulations, but has also seen much use for geometry optimization. It uses five valence terms, one of which is an electrostatic term, and one cross tenn. 

Halgren TA. Merck molecular force field. I. Basis, form, scope, parameterization and performance of MMFF94. J Comput Chem 1996 17 490-519. 

Halgren, T. A. Merck Molecular Force Field. HI. Molecular geometries and vibrational frequencies for MMFF94. J Comput Chem 1996,17 553-86. 

Halgren TA, Nachbar RB. Merck molecular force field. IV. Conformational energies and geometries. / Comput Chem 1996 17 587-615. 

T. A. Halgren, Merck molecular force field. II. MMFF94 van der Waals and electrostatic parameters for intermolecular interactions, J. Comput. Chem. 17 520 (1996). 

MMFF94. Merck Molecular Force Field. A Molecular Mechanics... 

These potential energy terms and their attendant empirical parameters define the force field (FF). More complicated FFs which use different and/or more complex functional forms are also possible. For example, the simple harmonic oscillator expression for bond stretching can be replaced by a Morse function, Euorse (3), or additional FF terms may be added such as the stretch-bend cross terms, Estb, (4) used in the Merck molecular force field (MMFF) (7-10) which may be useful for better describing vibrations and conformational energies. 

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