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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.
The global search of low energy structure of AlnMgm (n + m = 6, 7; m = 1, 2) is made by genetic algorithm and empirical potential. The stability and electronic structure of AlnMgm are studied by ab initio calculation. The close isomer, the Mg-Mg interaction in Al Mg clusters is far weaker than the Al-Al interaction, and the Mg atoms tend to form more Mg-Al bonds in the stable structure. The NBO charge analysis shows The electron transfer from Mg to Al strongly depends on the number of Mg atoms attached to the Al atom.The electron structure analysis shows that as the number of atoms increases, the occupied orbital energy level decreases slightly, and when Mg is doped with the same size Lower energy level; Al Mg cluster energy gap of about 5.30 eV.