Strukturelle und energetische Eigenschaften von bimetallischen Clustern

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A systematic and complete investigation of the structural, energetic, vibrational, and thermodynamic properties of bimetallic clusters AmBn with N = m + n from 2 to 60 will be carried through for each cluster size and each composition. As metals we consider Ni, Cu, Ag, Pt, Pd, and Au, that have different atomic radii as well as bulk and surface properties, in order to understand both generic and material-specific features. The lowest-energy structures are to be determined using a combination of the embeddedatom method to model the interatomic interaction and the basin-hopping algorithm for the unbiased determination of the global total-energy minimum. The most stable stoichiometries shall be identified by using various definitions of stability functions, the excess energy, and the energy difference between the first and second lowest isomers. The obtained lowest-energy structures will be further optimized by more advanced density functional theory methods employing the realistic exchange-correlation potentials determined for each metal pair A–B by using the procedure developed by us. Furthermore, the full vibrational spectrum of the nanoalloys will be calculated. Finally, with help of the harmonic superposition approximation the thermodynamic properties, including heat capacity, Debye temperature, and solidsolid phase transition temperatures, will be calculated for the first time. The derived results including the developed schemes and procedures can be used in different fields of cluster science such as ”Structure and thermodynamics”, ”Electronic structure and quantum (size) effects”, ”Spectroscopy and dynamics”, ”Catalysis”, ”Optical properties and plasmonics”.