PERFORMANCE OF THE SHIFT METHOD OF GLOBAL MINIMIZATION IN SEARCHES
FOR OPTIMUM STRUCTURES OF CLUSTERS OF LENNARD-JONES ATOMS
PILLARDY J, OLSZEWSKI KA, PIELA L
JOURNAL OF PHYSICAL CHEMISTRY 96 (11): 4337-4341 MAY 28 1992
Document type: Article |
Language: English |
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Abstract:
The optimal geometry of a finite cluster of atoms is difficult to find because
the number of minima of the potential energy is huge for larger clusters. Until
now, the only deterministic procedure designed to find the lowest-energy
structures of such clusters was the diffusion equation method, which performed
well for large clusters but sometimes failed for smaller ones. In the present
paper we propose the so-called shift method (also deterministic), which deforms
the original potential energy hypersurface by shifting the atom-atom Lennard-Jones
potential. As a result, the whole system collapses into a single point. Then, by
using the reversing procedure, the original potential is gradually restored
while optimizing the structure for each step. This results in a kind of big
bang, because the atoms emerge from the collapse point and the cluster geometry
evolves to the final one corresponding to the original undeformed potential. The
procedure applied to the clusters containing up to 19 atoms turned out to
produce in all cases under study the structures of the lowest energy.