1 The background and significance of the research

Metal cluster science is an interdiscipline of physics and chemistry, which has become a new growth point of material science in recent years. It has many special properties, such as magic number, magnetic stability and surface chemical activity. Meanwhile, metal clusters are closely related to many basic science and applied science. Therefore, the science of metal clusters has become a hot research topic. The initial study of metal clusters is to understand their stable geometric structures and electronic structures. However, the direct determination of free metal clusters is relatively difficult and it#8217;s a complex global optimization to determine the ground state structure of the metal cluster.

This thesis is based on the density functional theory(DFT), quantum chemistry, molecular graphics. At beginning of our research, we will use quantum chemical calculation software ,such as VASP, P4VASP and VESTA, to design and calculate the geometric structure, stability, electronic structure, charge distribution, electronic energy state, physical and chemical properties of 13-and 55-atoms Fe@Cu and Cu@Fe alloy core-shell particles. We will further discuss the properties#8217; difference between Fe@CuCu@Fe core-shell structure alloy and FeCu pure metal.

2 Literature Review

2.1 Core-shell Nanoparticles and Metal CSNs

Core#8211;shell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. In contrast to their bulk counterparts, core-shell nanoparticles#8217; geometric structures is intriguing^[1]. By rationally tuning the cores as well as the shells of such materials, a range of core#8211;shell nanoparticles can be produced with tailorable properties that can play important roles in various catalytic processes and offer sustainable solutions to current energy problems. The roles of various classes of CSNs are exemplified for both catalytic and electrocatalytic applications, including oxidation, reduction, coupling reactions, etc.^[2]

The broad class of ””metal-based CSNs#8217;#8217; requires subclassification, as it covers the entire range of metal, metal alloys, metal oxides, metal salts, etc. and can thus be sub-divided into three parts: (i) metallic NPs, (ii) metal oxides, and (iii) metal salts.

In general, metallic NPs are synthesized via reduction of their corresponding metal-salts, either using external reducing agents (such as NaBH-4-hydrazine) or via rans-metallation utilizing the intrinsic redox properties of the metal precursors. The reaction medium, temp- erature and type of reducing agent influence the reaction kinetics, and any manipulation of these parameters may lead to significant differences in particle growth, size, shape, and thereby different chemical, physical, optical and biological properties.

2.2 Properties of metal CSNs

2.2.1 Magic number