The Effect of Potential Parameterisation on Bimetallic Nanoclusters
Ramli ISMAIL1 and Roy L. JOHNSTON1
1School of Chemistry, University of Birmingham, B15 2TT, UK
The semi-empirical Gupta potential has been finely tuned in several ways by modifying the bimetallic potential parameters (A, ξ, p, q and r0).The effect on different type of metals (p-block, 2nd-row, 3rd-row and 4th-row transition metals) have been studied using a genetic algorithm global optimization technique, using the BlueBEAR supercomputer. Observation of the energetics, structures and segregation show that the heteronuclear bonding in the bimetallic clusters studied (Palladium-Platinum, Palladium-Gold, Nickel-Aluminium) are strongly dependent on the potential parameters. Specific parameterisations can produce very similar results to those obtained using higher levels of theory. Structural analysis shows competition between several structural families and this study allowed us to identify five main types of chemical ordering; core-shell, spherical cap, ball-and-cup, (intermediate between the first two types), and mixed.
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