【摘要】 采用密度泛函理论(DFT)在B3LYP/6-311+G(d)水平上,对NamSi7-m(m≤6)团簇的最低能量结构和电子性质进行了研究.结果表明:m≤4时,团簇的稳定结构倾向于Na原子附着在带负电的Si7-m结构的不同位置上,Na原子成分较多时(m≥4)混合团簇的稳定几何结构发生较大的变化,且团簇中Nam的结构与单一的Nam团簇的稳定结构不同;自然电荷布居分析表明,电荷从Na原子转移到Si原子;随着Na原子成分的增加,团簇越来越容易失去电子,且团簇的稳定性也随之减弱;随着m的增加能隙出现振荡,其中Na5Si2的能隙最小,化学活性最强,Na2Si5的能隙最大,化学活性最弱.更多还原

【Abstract】 The equilibrium geometries and electronic properties of NamSi7-m(m≤ 6) clusters have been studied by using density functional theory at the B3LYP/6-311+G(d) level.The results indicate that the lowest energy isomer tend toward adsorption geometries where Na atoms are attached to a Si7-m(m≤4) framework with pronounced negative charge,It is also seen that the geometries of Na-rich clusters are significantly changes and the arrangement of Na atoms is different from that of Nam(m≥4).According to the Natural Charge population analysis,Charges transfer from Na to Si atoms.With increasing number of Na atoms,NamSi7-m clusters tend losing electrons and their stabilities get weaker.Furthermore,the calculated highest occupied molecular orbital and lowest unoccupied molecular orbital(HOMO-LUMO) gaps of the most stable NamSi7-m clusters oscillate with increasing size of m while the gap of the Na5Si2 is the lowest reflecting highest reactivity and that of the Na2Si5 is the vice versa.更多还原