【摘要】 用遗传算法结合经验势对AlnMgm(n+m=6,7;m=1,2)的低能结构进行全局搜索,用从头计算方法研究了其稳定性和电子结构.计算表明AlnMgm存在多个能量相近的异构体,在Al Mg团簇中Mg-Mg相互作用远弱于Al-Al作用,稳定结构中Mg原子倾向于形成更多的Mg-Al键.自然键轨道(NBO)电荷分析表明Mg向Al转移电子,Al原子上的电荷大小强烈依赖于相连的Mg原子个数.电子结构分析表明随着原子数目的增大,占据轨道能级略有降低,同尺寸下掺杂一个Mg时能级更低;Al Mg团簇的能隙约为5.30 e V.更多还原

【Abstract】 The global low-energy structures of AlnMgm( n + m = 6,7; m = 1,2) clusters are searched by using genetic algorithm combined with empirical potentials,the stability and electronic structure are studied by ab initio method. The results indicate that AlnMgmclusters have a few isomers with close energies. The interaction between Mg atoms is much weaker than the interaction between Al atoms,and magnesium atoms tend to form more Mg-Al bonds in the stable structures. NBO charge indicates that magnesium transfers electrons to aluminum,and the charge on Al atoms depends strongly on the number of connected Mg atoms. Analysis on the electronic structure shows that the energy levels of occupied orbital decrease slightly with the increase of the cluster size,and the levels are lower when the cluster contains only one magnesium atom. The energy gap of AlnMgmcluster is about 5. 30 e V.更多还原