A note on the application of the "Boltzmann simplex"-simulated annealing algorithm to
global optimizations of argon and water clusters
Francis M. Torres, Eugene Agichtein,
Leonid Grinberg, Guowei Yu, Robert Q. Topper*
Department
of Chemistry, The Cooper Union for the Advancement
of Science and Art, Albert Nerken School of Engineering,
51 Astor Place, New York, NY 10003
This eprint was originally presented in October 1996
as part of the Third Electronic
Computational Chemistry Conference (ECCC-3).
It was then
published in the Journal of Molecular
Structure (THEOCHEM) 419, 85 (1997)
Abstract
We report our application of a recently published simulated annealing
algorithm which we call "Boltzmann
simplex"-simulated annealing (BSSA) to global optimizations
of argon and water
clusters. The Lennard-Jones model of argon
clusters serves as a challenging benchmark for global optimization methods, and we use it
as a test case. We find that the BSSA method
is most useful when followed by a local optimization via the
Powell method. This is because the Powell method
quenches to the equilibrium geometry more effectively than a downhill simplex,
which is the zero-temperature limit of the BSSA algorithm. We also find that very slow
annealing rates are required to achieve acceptable results. A study of small water clusters
[(H2O)m, m=2-6] using a recently published flexible-monomer interaction potential
yields ringlike structures, in good agreement with other theoretical and
experimental studies, for m=2-5. A highly puckered ring structure is
obtained for m=6.
*Corresponding author. Email address: topper@cooper.edu.