Boukari Khaoula, Duverger Eric, Sonnet Philippe
Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, Université de Haute Alsace, 3b rue Alfred Werner, 68093 Mulhouse cedex, France.
Phys Chem Chem Phys. 2014 Dec 7;16(45):24866-73. doi: 10.1039/c4cp03347g.
We investigate the adsorption mechanism of a single trans 4-pyridylazobenzene molecule (denoted by PAB) on a doped boron Si(111)√3×√3R30° surface (denoted by SiB) with or without boron-defects, by means of density functional theory calculations. The semiempirical approach proposed by Grimme allows us to take the dispersion correction into account. The role of the van der Waals correction in the adsorption geometries and energies is presented. In particular, two adsorption configurations are electronically studied. In the first one, the molecule is parallel to the surface and interacts with the SiB surface via the -N=N- bond. In the presence of a boron-defect, a Si-N chemical bond between the molecule and the surface is then formed, while electrostatic or/and van der Waals interactions are observed in the defectless surface. In the second adsorption configuration, the molecule presents different orientations with respect to the surface and interacts via the nitrogen atom of the pyridyl part of the PAB molecule. If the molecule is perpendicular to the perfect SiB surface, the lone-pair electrons associated with the heterocyclic nitrogen atom fill the empty dangling bond of a silicon adatom via a dative bond. Finally, in the presence of one boron-defect, the possibility of a "forced" dative bond, corresponding to a chemical bond formation between the PAB molecule and the silicon electron occupied dangling bond, is emphasized.
我们通过密度泛函理论计算，研究了单个反式4-吡啶基偶氮苯分子（记为PAB）在有或无硼缺陷的掺杂硼Si(111)√3×√3R30°表面（记为SiB）上的吸附机制。Grimme提出的半经验方法使我们能够考虑色散校正。阐述了范德华校正在吸附几何结构和能量中的作用。特别地，对两种吸附构型进行了电子学研究。在第一种构型中，分子与表面平行，并通过-N=N-键与SiB表面相互作用。在存在硼缺陷的情况下，分子与表面之间会形成Si-N化学键，而在无缺陷表面则观察到静电或/和范德华相互作用。在第二种吸附构型中，分子相对于表面呈现不同的取向，并通过PAB分子吡啶部分的氮原子相互作用。如果分子垂直于完美的SiB表面，与杂环氮原子相关的孤对电子通过配位键填充硅吸附原子的空悬键。最后，在存在一个硼缺陷的情况下，强调了“强制”配位键的可能性，即PAB分子与硅电子占据的悬键之间形成化学键。
