Multi-time scale integration.

[Guido Germano <g.germano #*at*# bristol.ac.uk>]

 > In the literature on multi-time scale integration, a lot of importance is
 > placed on time reversibility.  Why this is so important is something
 > that I have never been able to figure out.  If an integration
 > algorithm is efficient and produces a small global error then why is
 > this not sufficient.  If anybody can enlighten me on this subject I
 > would appreciate it.
 >
 > --
 > Don Steiger
 > dons #*at*# hamilton.math.missouri.edu
 Newton's equations are time-reversible, and Hamiltonian dynamics
 preserves phase space volume. Non-reversible integration schemes do not
 preserve volume in phase space and usually show also long-term energy
 drifts. The reasons for wanting time-reversibility are therefore
 eminently physical and not mathematical. A good reference is the book by
 Daan Frenkel and Berends Smit, "Understanding Molecular Simulation",
 Academic Press 1996.
 Regards
 Dr. Guido Germano
 Research Assistant in Theoretical Physics, University of Bristol, England
 Tel. +44-117-928 9000 ext. 8755, http://www.phy.bris.ac.uk/staff/germano_g.html