Amber

Amber is the collective name for a suite of programs that allow users to carry out molecular dynamics simulations, particularly on biomolecules. None of the individual programs carries this name, but the various parts work reasonably well together, and provide a powerful framework for many common calculations. The term amber is also sometimes used to refer to the empirical force fields that are implemented here. It should be recognized however, that the code and force field are separate: several other computer packages have implemented the amber force fields, and other force fields can be implemented with the amber programs. Further, the force fields are in the public domain, whereas the codes are distributed under a license agreement.
Amber refers to two things: a set of molecular mechanical force fields for the simulation of biomolecules (which are in the public domain, and are used in a variety of simulation programs); and a package of molecular simulation programs which includes source code and demos.