From chemistry-request@www.ccl.net Tue Sep 15 06:43:51 1998 Received: from cockatoo.phy.bris.ac.uk (cockatoo.phy.bris.ac.uk [137.222.30.7]) by www.ccl.net (8.8.3/8.8.6/OSC/CCL 1.0) with SMTP id GAA17930 Tue, 15 Sep 1998 06:43:50 -0400 (EDT) Received: by cockatoo.phy.bris.ac.uk id AA28899; Tue, 15 Sep 1998 11:43:33 -0400 Date: Tue, 15 Sep 1998 11:43:33 -0400 (EDT) From: Guido Germano X-Sender: guido@cockatoo.phy.bris.ac.uk Reply-To: Guido Germano To: Computational Chemistry List Subject: Multi-time scale integration. In-Reply-To: <199809150520.BAA17091@www.ccl.net> Message-Id: Organization: Physics Department University of Bristol Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII > 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@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