MgScH15: A highly stable cluster for hydrogen storage

Mg-Sc-H systems exhibit superior stability and high hydrogen storage capacity among the large class of magnesium-based hydrogen storage materials, but the underlying mechanisms for their outstanding hydrogen storage properties remain largely unexplored and require further investigation. Here, we have performed a comprehensive investigation on the structural evolution of MgScH_n (n = 10–20) clusters by unbiased Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method combined with density functional theory (DFT) optimizations at the B3PW91/6-311 + G(d) level. Our results show that the MgScH₁₅ cluster with C_s symmetry is found to be the most stable cluster with good hydrogen storage capacity of 17.8 wt% due to the strong interaction among the 1s orbitals of the H atoms, the 2p orbitals of the Mg atom and the 3d orbitals of the Sc atom. The present findings are promising for further exploring novel hydrogen storage nanomaterials.     

Micromechanism study on electronic and magnetic properties of silicene regulated by oxygen

Silicene, a two-dimensional (2D) silicon counterpart of graphene with attractive electronic properties, has attracted increasing attention. Understanding of its interaction with oxygen is of fundamental importance for nano-electronics in silicon-based technology. Here, we have systematically studied the structural, electronic and magnetic properties of silicene with oxygen atoms adsorption by using an unbiased structure search method coupled with First-principles calculations. The results show that the most favorable oxygen adsorption site on silicene surface is bridge site and oxygen atoms tend to chemisorb on silicene. A detailed analysis of the electronic band structure and density of state (DOS) suggests that there is a band gap opening near Fermi level after oxygen adsorption, which lead to pristine silicene changing from a gapless semiconductor to a direct or indirect bandgap semiconductor. The important finding is that two and six oxygen atoms adsorbed silicene are more advantageous due to the relatively large direct band gaps at the K point. The calculated magnetic moments and spin density isosurfaces reveal that the total magnetic moments are mostly localized on silicene sheet. This finding provides new insights for further materials design based on two-dimensional silicon systems.     

双金属AunCu0- (n=1~9) 团簇结构、稳定性、电子及光学性能研究

为了探究铜掺杂金团簇的结构及特性,依据密度泛函理论对Au_nCu^{0/-(n=1~9)团簇的结构、稳定性、电子及光学性能进行了系统分析。基于卡利普索结构预测程序,在B3LYP/Lanl2dz水平下优化得到了不同尺寸的基态结构。研究表明,除Au₇Cu和Au₈Cu-呈现三维结构外,其它尺寸下的基态均呈现二维平面结构。而且,Au_nCu0/-的基态可通过在Aun-1Cu0/-}基态基础上添加一个Au原子得到。稳定性分析确定了Au₅Cu和Au₂Cu-团簇在各自体系中拥有相对强的稳定性。磁性分析发现,闭壳层电子结构体系的总自旋磁矩为零;开壳层电子结构体系分别具有1 μB的总磁矩。分析极化率表明,Au₉Cu和Au₉Cu-团簇对外场的各向异性响应最强,AuCu和Au₃Cu-团簇对外场的各向异性响应最弱。AdNDP分析发现,众多σ键连通了整个分子骨架,促进了整个团簇的稳定。基于Multiwfn程序,拟合的光电子能谱、红外谱、拉曼谱和紫外可见光谱可为实验上鉴别Au_nCu^0/-团簇的结构提供帮助。