Molecular force field

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. 

Dykstra C E 1993. Electrostatic Interaction Potentials in Molecular Force Fields. Chemical Review 93 2339-2353. 

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. 

Microwave studies also provide Important Information regarding molecular force fields, particularly with reference to low frequency vibrational modes in cyclic structures (74PMH(6)53). 

The parameters in molecular force fields (e.g., Kb, Ke, A, and B) can be determined by using them to calculate different independent molecular... 

This article reviews progress in the field of atomistic simulation of liquid crystal systems. The first part of the article provides an introduction to molecular force fields and the main simulation methods commonly used for liquid crystal systems molecular mechanics, Monte Carlo and molecular dynamics. The usefulness of these three techniques is highlighted and some of the problems associated with the use of these methods for modelling liquid crystals are discussed. The main section of the article reviews some of the recent science that has arisen out of the use of these modelling techniques. The importance of the nematic mean field and its influence on molecular structure is discussed. The preferred ordering of liquid crystal molecules at surfaces is examined, along with the results from simulation studies of bilayers and bulk liquid crystal phases. The article also discusses some of the limitations of current work and points to likely developments over the next few years. 

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. 

Hagler, A. T., Ewig, C. S. On the use of quantum energy surfaces in the derivation of molecular force fields. Comput. Phys. Commun. 1994, 84, 131-155. 

Amodeo, P., and V. Barone. A New General Form of Molecular Force Fields. Application to Intra- and Interresidue Interactions in Peptides. J. Am. Chem. Soc. 114, 9085-9093. 

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

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