Due to the dependence of the chemical and physical properties of the bimetallic nanoparticles（NPs） on their structures,a fundamental understanding of their structural characteristics is crucial for their syntheses a...Due to the dependence of the chemical and physical properties of the bimetallic nanoparticles（NPs） on their structures,a fundamental understanding of their structural characteristics is crucial for their syntheses and wide applications. In this article, a systematical atomic-level investigation of Au–Pd bimetallic NPs is conducted by using the improved particle swarm optimization（IPSO） with quantum correction Sutton–Chen potentials（Q-SC） at different Au/Pd ratios and different sizes. In the IPSO, the simulated annealing is introduced into the classical particle swarm optimization（PSO） to improve the effectiveness and reliability. In addition, the influences of initial structure, particle size and composition on structural stability and structural features are also studied. The simulation results reveal that the initial structures have little effects on the stable structures, but influence the converging rate greatly, and the convergence rate of the mixing initial structure is clearly faster than those of the core-shell and phase structures. We find that the Au–Pd NPs prefer the structures with Au-rich in the outer layers while Pd-rich in the inner ones. Especially, when the Au/Pd ratio is 6：4, the structure of the nanoparticle（NP） presents a standardized Pd（core） Au（shell） structure.展开更多
合金纳米团簇可以充分利用多种金属的协同效应来实现材料的多功能特性,因而备受关注.本文利用改进的Basin-Hopping Monte Carlo算法研究了不同尺寸和不同比例下的Fe-Pt二元合金团簇的结构稳定性.为证明初始结构相关性,引入了相似函数来...合金纳米团簇可以充分利用多种金属的协同效应来实现材料的多功能特性,因而备受关注.本文利用改进的Basin-Hopping Monte Carlo算法研究了不同尺寸和不同比例下的Fe-Pt二元合金团簇的结构稳定性.为证明初始结构相关性,引入了相似函数来分析合金团簇稳定结构与其对应的单金属团簇结构之间的相似性,并分析了Fe-Pt合金团簇在稳定结构下的元素分布.研究结果表明:对于N≤24的Fe-Pt含金团簇,其结构并没有随原子数的增长呈现出明显的形状变化.但是就原子分布而言,对于相同尺寸下不同比例的原子结构,Fe元素趋向于分布在外层,而Pt元素更趋向于分布在内层;对于相同比例不同尺寸的原子结构也得到了同样的结论,并且在Fe原子比例越大的情况下,这种趋向的分布越明显.此外,通过计算合金团簇与单一金属团簇的结构相似函数,发现N≤24的Fe-Pt合金团簇在吸收Fe单金属和Pt单金属基态结构的基础上,随着元素比例的变化,发生了不同于单金属基态结构的变化,并且不同比例结构差异较大.最后,通过计算Fe-Pt合金团簇能量的二阶有限差分值,在Fe-Pt表现出分离结构状态时找到了相对稳定度最好的稳定结构.展开更多
The structural stability and magnetic properties of the icosahedral Ni13, Ni13^＋1 and Ni13^-1 clusters have been obtained by utilizing all-electron density functional theory with the generalized gradient approximatio...The structural stability and magnetic properties of the icosahedral Ni13, Ni13^＋1 and Ni13^-1 clusters have been obtained by utilizing all-electron density functional theory with the generalized gradient approximations for the exchange-correlation energy. The calculated results show that the ground states of neutral and charged clusters all favour a D3d structure, a distorted icosahedron, due to the Jahn-Teller effect. The radial distortions caused by doping one electron and by doping one hole are opposite to each other. Doping one electron will result in a 1/2 decrease and doping one hole will result in a 1/2 increase of the total spin. Both increasing interatomic spacing and decreasing coordination will lead to an enhancement of the spin magnetic moments for Nil3 clusters.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11474234 and 61403318)the Fundamental Research Funds for the Central Universities of China(Grant No.20720160085)
文摘Due to the dependence of the chemical and physical properties of the bimetallic nanoparticles（NPs） on their structures,a fundamental understanding of their structural characteristics is crucial for their syntheses and wide applications. In this article, a systematical atomic-level investigation of Au–Pd bimetallic NPs is conducted by using the improved particle swarm optimization（IPSO） with quantum correction Sutton–Chen potentials（Q-SC） at different Au/Pd ratios and different sizes. In the IPSO, the simulated annealing is introduced into the classical particle swarm optimization（PSO） to improve the effectiveness and reliability. In addition, the influences of initial structure, particle size and composition on structural stability and structural features are also studied. The simulation results reveal that the initial structures have little effects on the stable structures, but influence the converging rate greatly, and the convergence rate of the mixing initial structure is clearly faster than those of the core-shell and phase structures. We find that the Au–Pd NPs prefer the structures with Au-rich in the outer layers while Pd-rich in the inner ones. Especially, when the Au/Pd ratio is 6：4, the structure of the nanoparticle（NP） presents a standardized Pd（core） Au（shell） structure.
文摘合金纳米团簇可以充分利用多种金属的协同效应来实现材料的多功能特性,因而备受关注.本文利用改进的Basin-Hopping Monte Carlo算法研究了不同尺寸和不同比例下的Fe-Pt二元合金团簇的结构稳定性.为证明初始结构相关性,引入了相似函数来分析合金团簇稳定结构与其对应的单金属团簇结构之间的相似性,并分析了Fe-Pt合金团簇在稳定结构下的元素分布.研究结果表明:对于N≤24的Fe-Pt含金团簇,其结构并没有随原子数的增长呈现出明显的形状变化.但是就原子分布而言,对于相同尺寸下不同比例的原子结构,Fe元素趋向于分布在外层,而Pt元素更趋向于分布在内层;对于相同比例不同尺寸的原子结构也得到了同样的结论,并且在Fe原子比例越大的情况下,这种趋向的分布越明显.此外,通过计算合金团簇与单一金属团簇的结构相似函数,发现N≤24的Fe-Pt合金团簇在吸收Fe单金属和Pt单金属基态结构的基础上,随着元素比例的变化,发生了不同于单金属基态结构的变化,并且不同比例结构差异较大.最后,通过计算Fe-Pt合金团簇能量的二阶有限差分值,在Fe-Pt表现出分离结构状态时找到了相对稳定度最好的稳定结构.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10574036 and 10574037）. and the Hebei Natural Science Foundation （Grant Nos A2004000141 and 2005000143）.
文摘The structural stability and magnetic properties of the icosahedral Ni13, Ni13^＋1 and Ni13^-1 clusters have been obtained by utilizing all-electron density functional theory with the generalized gradient approximations for the exchange-correlation energy. The calculated results show that the ground states of neutral and charged clusters all favour a D3d structure, a distorted icosahedron, due to the Jahn-Teller effect. The radial distortions caused by doping one electron and by doping one hole are opposite to each other. Doping one electron will result in a 1/2 decrease and doping one hole will result in a 1/2 increase of the total spin. Both increasing interatomic spacing and decreasing coordination will lead to an enhancement of the spin magnetic moments for Nil3 clusters.
