On basis of bond dissociation energies （BDEs） for BH2, B（OH）2, BCl2, and BCl, the diffusion Monte Carlo （DMC） method is applied to explore the BDEs of HB-H, HOB-OH, ClB-Cl, and B-Cl. The effect of the choice of orbitals, as well as the backflow transformation, is studied. The Slater-Jastrow DMC algorithm gives BDEs of 359.1±0.12 kJ/mol for HB-H, 410.5±0.50 kJ/mol for HOB-OH, 357.8±1.46 kJ/mol for ClB-Cl, and 504.5±0.96 kJ/mol for B-Cl using B3PW91 orbitals and similar BDEs when B3LYP orbitals are used. DMC with backflow corrections （BF-DMC） gives a HB-H BDE of 369.9±0.12 kJ/mol which is close to one of the available experimental value （375.8 kJ/mol）. In the case of HOB-OH BDE, the BF-DMC calculation is 446.04-1.84 k J/mol that is closer to the experimental BDE. The BF-DMC BDE for ClB-Cl is 343.2±2.34 kJ/mol and the BF-DMC B-Cl BDE is 523.3±0.33 kJ/mol, which are close to the experimental BDEs, 341.9 and 530.0 kJ/mol, respectively.
基于含时密度泛函理论,研究了硅烯量子点的等离激元激发.沿量子点所在的平面方向,体系中有两个主要的等离激元共振带.一个等离激元共振带位于2.0 e V附近,另一个等离激元共振带位于7.0 e V附近.由于离域化的π电子参与了两个等离激元共振带的激发,沿激发方向随着矩形硅烯量子点边长的增加,体系的两个等离激元共振带都发生红移.硅烯量子点的等离激元激发还依赖于边界的构型.此外,由于六角形硅烯量子点的对称性较高,沿量子点所在平面的不同方向激发时,体系的等离激元共振模式相同.
