Tinker is a set of small programs for doing general purpose molecular
modeling calculations. Tools are included for energy minimizations,
geometry calculations, simulated annealing, molecular dynamics, and
molecular analysis calculations. Tools for converting coordinate sets
are also provided.  Tinker employs several force fields and minimization
techniques.

This port sets the maxatm value to 2500 atoms.  This should be
sufficient for most molecular systems.  Should you need to work with
larger systems you can set the maxatm parameter in the sizes.i file
located in the tinker/source directory and recompile.  Note that if it
is set too large that tinker programs will abort and core dump.

For more information about Tinker see:

WWW: http://dasher.wustl.edu/tinker/