Ga3O2-和Ga4O3-的结构及稳定性的研究

Research on the structures and stability of Ga_3O_2^-and Ga_4O_3^-

采用密度泛函理论(DFT)中的B3LYP方法和BP86方法,O原子基于6-311+G(d,p)基组,Ga原子基于Stuttgart基组,对Ga_3O_2^-/0与Ga_4O_3^-/0团簇的各种可能构型进行了几何优化,预测了各团簇的最稳定结构,并研究了Ga_3O_2^-和Ga_4O_3^-最稳定结构的成键特性、振动特性和稳定性。对比B3LYP和BP86计算结果发现得到的异构体的结构和能量顺序相同,且阴离子的基态构型与中性分子的构型相接近,都是平面C_(2v)型,都存在由2个Ga原子和一个O原子形成的三中心二电子(3c-2e)桥键。两结构中处于端位的"Ga-O"键的Wiberg键级数值较大,分别为0.50、0.55;振动频率分别为713.92、832.76cm-1,在红外谱图上皆对应一明显的强振动峰,表明该"Ga-O"结构单元成键稳定,是决定团簇结构稳定的重要因素。计算得到是Ga_3O_2^-和Ga_4O_3^-基态结构的LUMO与HOMO的能量之差(分别为2.75、2.84eV),以及电子绝热剥离能(ADE)和电子垂直剥离能(VDE),都表明两基态结构具有较好的热力学稳定性。

Possible geometrical structures and relative stability ofGa3O2-and Ga4O3- clusters are studied by using B3LYP and BP86 methods with O selected 6-311＋G （d, p） basis set and Ga selected Stuttgart basis set. For the most stable isomers of clusters, the bond properties, vibration properties and stability are analyzed. Calculated results suggest that the low-lying structures and energy orders of Ga302- and Ga4O3-are same and the ground state structures of neutral clusters are similar to anions＇. The ground states of Ga3O2- and Ga4O3- are planar structures with C2V symmetry, where exist a three-center-two-electron （3c-2e） bond formed by two Ga atoms and one O atom. The terminal Ga-O bond in two structures have a larger Wiberg Bond Indexes responding to 0.50 and 0.55 respectively, and its vibration frequencies are 713.92 and 832.76 cm-1, which are corresponding to a clear strong vibration peak in the infrared spectrums. So it can be concluded that the＂ Ga-O＂ subunit forms stable bonds which is crucial for structure stability of the clusters. Calculated values including the energy difference between LUMO and HOMO （respectively 2.75, 2.84 eV）, adiabatic electron detachment energy （ADE） and vertical electron detachment energy （VDE） show that two ground state structures ofGa3O2-and Ga4O3- clusters have good thermodynamic stability.