MOLECULAR-DYNAMICS ON DEFORMED POTENTIAL-ENERGY HYPERSURFACES
PILLARDY J, PIELA L
JOURNAL OF PHYSICAL CHEMISTRY 99 (31): 11805-11812 AUG 3 1995
Document type: Article |
Language: English |
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Abstract:
In the classical molecular dynamics for a complicated system the trajectory
remains relatively close to any arbitrarily chosen starting configuration of the
nuclei. This is because of a prohibitively large volume of the configurational
space as well as of energy barriers between numerous potential energy basins. In
the present paper the molecular dynamics is performed on a deformed potential
energy hypersurface. The deformation is tunable, and when increased, the
barriers become lower or even disappear; therefore, the system is able to
explore much larger regions of the configurational space. The deformation is
slowly released, and finally the molecular dynamics is continued on the
undeformed potential energy hypersurface. As a result of such a procedure, some
low-energy structures may be found in a more effective way. The method has been
applied to the clusters of the N Lennard-Jones atoms, N = 5,..., 66, which is
the most extensive systematic study of the clusters published till now. The
energies of the clusters are lower than those obtained by the classical
molecular dynamics (at the same numerical effort) for the starting points being
far away from the lowest energy region. Contrary to the molecular dynamics, they
are independent of the starting point to a significant degree. The size of the
most stable cluster turned out to be a stepwise increasing function of N, which
reflects building of new atomic shells. However, for N = 38 some qualitative
change of the structure to the one characteristic for the infinite crystal
occurs and the cluster size becomes abnormally low when compared to the clusters
with N < 38 and N > 38.