In general physics, a force field is a vector field representing the gradient of a potential. The vectors that are the values of a force field are forces, and so measured in units of force such as newtons and pounds-force.

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In the context of molecular dynamics, a force field (also called a forcefield) is a more loosely defined term and refers to the functional form and parameter sets used to describe the interactions (potential, forces) within a system of particles (atoms or similarly sized objects). It is independent of the system's configuration and is not a numerical field as in the above context. A force field can be empirical, derived from higher-level modelling (e.g. quantum chemical studies), or even heuristic.

Some popular forcefields and the types of molecules they can be applied to include:

Classical forcefields:

• AMBER - widely used for proteins and DNA
• CHARMm - originally developed at Harvard, widely used for both small molecules and macromolecules
• CVFF - also broadly used for small molecules and macromolecules
• GROMACS -
• GROMOS -
• MM2, MM3, MM4 - developed by Norman L. Allinger, for a broad range of chemicals
• OPLS, OPLSAA - developed by William L. Jorgensen

Second-generation forcefields:

• CFF - a family of forcefields adapted to a broad variety of organic compounds, includes forcefields for polymers, metals, etc.
• MMFF - developed at Merck, for a broad range of chemicals

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In science fiction and fantasy literature, a force field is a physical barrier made up of energy to protect a person or object from attacks or intrusions.

External link

• Force field (http://memory-alpha.org/en/index.php/Force_field) at Memory Alpha, a Star Trek WikiWiki