The geometries, stability and chemical bonding of XB6+(X=C, Si, Ge, Sn, Pb) dusters were investigated using ab initio (MP2) and density functional theory (DFT: B3LYP and B3PW91) methods.Analytical gradients with polarized split-valence basis sets (6-311 +G(d)) were used for B, C, Si, and Ge.The relativistic effective core potential with the LANL2DZ basis sets were chosen for Sn and Pb.The results show that the Cs symmetric pseudo-planar XB6+(X=C, Si, Ge, Sn, Pb) structures are the global minima on the potential energy surfaces, which are more stable than the C6v symmetric pyramidal and C2symmetric quasi-pyramidal structures.We carried out a natural bond orbital (NBO) analysis of all these minima at the B3LYP level, and calculated and discussed the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps, the molecular orbitals (MO), and the nucleus-independent chemical shifts (NICS) of the most stable structure.The nature of the X-B and B=B bonds in these minimum structures and the aromatic characteristics (σ and π) of the most stable configuration were analyzed at the B3LYP level.%利用从头算MP2方法和密度泛函理论B3LYP和B3PW91方法,研究了杂硼原子簇XB+6(X=C,Si,Ge,Sn,Pb)的结构、稳定性及化学键合情况.对C,Si,Ge,B使用6-311+G(d)基组,对Sn和Pb使用LANL2DZ赝势基组.研究结果表明,具有Cs对称性的假平面XB+6(X=C,Si,Ge,Sn,Pb)结构是势能面上的全域极小点,其稳定性要高于Csv对称性的锥形结构和C2对称性的假锥形结构.在B3LYP水平上,对这些异构体的势能面的极小点进行了自然键轨道(NBO)的分析;对最稳定构型的最高占据分子轨道(HOMO)和最低空轨道(LUMO)能级差、分子轨道(MO)和核独立化学位移(NICS)进行了计算和讨论.分析了杂原子和硼原子间、相邻硼原子间的键合情况,讨论了最稳定构型的芳香性质.
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