Strukturelle und energetische Eigenschaften von bimetallischen Clustern

对N=m+n的双金属团簇AmBn的结构、能量、振动和热力学性质进行了系统而全面的研究，其中N=m+n从2到60。作为金属，我们考虑具有不同原子半径以及体积和表面属性的镍、铜、银、铂、钯和金，以了解一般和特定材料的特征。最低能量结构将使用嵌入基准法和盆地跳跃算法相结合来确定，前者用于模拟原子间相互作用，后者用于无偏见地确定全球总能量最小值。最稳定的化学计量比应通过使用稳定性函数、过剩能量和第一和第二最低异构体之间的能量差的各种定义来确定。所得到的最低能量结构将通过更先进的密度泛函理论方法进一步优化，这些方法采用我们开发的程序，利用为每个金属对A-B确定的真实交换相关势。此外，还将计算纳米合金的全振动光谱。最后，借助于调和叠加近似，首次计算了热力学性质，包括热容、德拜温度和固-固相变温度。所得结果可用于“结构与热力学”、“电子结构与量子(尺寸)效应”、“光谱与动力学”、“催化”、“光学性质与等离子体”等团簇科学的不同领域。

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”.