Strukturelle und energetische Eigenschaften von bimetallischen Clustern

本文将对N = m + N范围为2 ~ 60的双金属团簇AmBn的结构、能量、振动和热力学性质进行系统而完整的研究。作为金属，我们考虑Ni， Cu, Ag, Pt， Pd和Au，它们具有不同的原子半径以及体积和表面特性，以便了解通用和材料特定的特征。用嵌入法模拟原子间相互作用，用盆地跳跃算法无偏确定全局总能量最小值，从而确定最低能量结构。最稳定的化学计量量应通过使用稳定性函数的各种定义、多余能量以及第一和第二最低同分异构体之间的能量差来确定。我们将采用更先进的密度泛函理论方法，利用我们开发的程序确定的每个金属对A-B的实际交换相关势，进一步优化得到的最低能量结构。此外，还计算了纳米合金的全振动谱。最后，在调和叠加近似的帮助下，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。推导的结果包括开发的方案和程序，可用于“结构和热力学”、“电子结构和量子（尺寸）效应”、“光谱学和动力学”、“催化”、“光学性质和等离子体学”等不同领域的团簇科学。

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”.