title: Energy landscape exploration of sub-nanometre copper-silver clusters.
abstract: The energy landscapes of sub-nanometre bimetallic coinage metal clusters are explored with the Threshold Algorithm coupled with the Birmingham Cluster Genetic Algorithm. Global and energetically low-lying minima along with their permutational isomers are located for the Cu(4)Ag(4) cluster with the Gupta potential and density functional theory (DFT). Statistical tools are employed to map the connectivity of the energy landscape and the growth of structural basins, while the thermodynamics of interconversion are probed, based on probability flows between minima. Asymmetric statistical weights are found for pathways across dividing states between stable geometries, while basin volumes are observed to grow independently of the depth of the minimum. The DFT landscape is found to exhibit significantly more frustration than that of the Gupta potential, including several open, pseudo-planar geometries which are energetically competitive with the global minimum. The differences in local minima and their transition barriers between the two levels of theory indicate the importance of explicit electronic structure for even simple, closed shell clusters.
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, Gothenburg (Sweden). christopher.heard@chalmers.se.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Heard
authors.affiliation: School of Chemistry, University of Birmingham, Edgbaston, Birmingham (UK).
authors.forename: Roy L
authors.initials: RL
authors.lastname: Johnston
authors.affiliation: Max Planck Institute for Solid-State Research, Heisenbergstrasse 1, 70569 Stuttgart (Germany).
authors.forename: J Christian
authors.initials: JC
authors.lastname: Schön
keywords: DFT; bimetallics; coinage metals; energy landscapes; subnanometre clusters