A Study On The Computational Simulation Of Precious Metal Alloy Clusters

Due to their unique and excellent catalytic,electromagnetic and optical properties,nano-alloy clusters have become research hotspots in the fields of electrochemistry and materials science,and have broad application prospects.The premise of studying the special properties of the cluster is to determine its stable structure,however,the theoretical calculation is needed to find the cluster stable structure.Computational simulation research was conducted on precious metal magic number clusters composed of large-sized Ag,Au,Pd,and Pt.The main contents of the paper are summarized as follows:1.The Gupta potential with experimental-fitted parameters and density-functional-theory?DFT?-fitted parameters combined with an improved adaptive immune optimization algorithm were respectively used to globally optimize98-atom Ag-Pd clusters.The structure,symmetry,energy and atom distribution's differences of this two groups of Ag-Pd clusters were compared.The results show that the main configurations of the two groups of Ag-Pd clusters are both Leary tetrahedrons,showing a magic number characteristic configuration.The secondary configuration of the experimental parameter group is face-centered cubic,while the secondary configuration of the DFT parameter group is icosahedron.Ag atoms have a strong tendency to occupy the surface in all stable structures.There exist differences in the growth modes of Ag and Pd atoms between the two groups.2.The improved algorithm combined with the Gupta potential function is used to calculate the 98-atom Au-Pd and Au-Pt clusters,and the structural analysis and comparison of these two clusters are implemented.The results show that the dominant structure of the two clusters is also Leary tetrahedron,followed by the face-centered cubic structure,but the distribution is obviously different,and other structures such as decahedron are also obtained.Au atoms have a strong surface segregation tendency.Pd atoms gather in the center and start to grow,and Pt atoms gather and grow from the secondary outer layer.Structural and energy analysis also show that configuration affects atom distribution and energy.Finally,the structure of 98 atom alloy clusters are summarized.3.In order to study the structure of M-Pd-Pt ternary series clusters,Ag_nPd₁₂Pt₁₂and Au_nPd₁₂Pt₁₂2 were optimized by AIOA-IC algorithm,and the most stable structures of some 100 and 147 atom Ag-Pd-Pt and Au-Pd-Pt clusters were compared and analyzed.The results show that in the Ag-rich Ag_n Pd₁₂Pt₁₂?n=1-60?clusters,the amorphous state with icosahedral fragments is the main structure.In the Au-rich Au_nPd₁₂Pt₁₂2 cluster,the main configuration is icosahedron,but there is structural competition between the icosahedron and the decahedron.The typical 100 and 147atoms Ag-Pd-Pt and Au-Pd-Pt clusters form a core-shell structure,and the Pd and Pt atoms are located at the core.However,there are obvious configuration differences between the two types of clusters.The Pd atoms in the Ag_nPd₁₂Pt₁₂2 cluster have more mixed characteristics with Ag and Pt atoms.These phenomena have been reasonably explained.