Si(001)表面硅氧团簇原子与电子结构的第一性原理研究

First-principles study of atomic and electronic structures of the silicon oxide clusters on Si(001) surfaces

在周期性边界条件下的k空间中,采用基于密度泛函理论的第一性原理广义梯度近似方法,对建立的规则对称型结构(A)、周期性非对称型结构(B)、周期性非对称型结构(C)、不规则型结构(D)四种可能的Si(001)表面硅氧团簇的结构模型进行了优化计算.结果表明优化后的表面结构呈无定形状,并且优化后的B,C,D三种模型的表面结构具有类似SiO2的四面体结构的几何特征.此外,通过电子局域函数图以及Mulliken布居分析发现硅氧团簇中的Si—O键既有明显的离子键成分,也有一定的共价键成分.

The possible models of the silicon oxide clusters on Si（001 ） surface, including the regular symmetric structure （A）, the periodic asymmetric structure （ B）, the periodic asymmetric structure （C） and the irregular structure （ D）, have been fully optimized using the first-principles general gradient approximation method based on density-functional theory. The results show that all the optimized surface structures are amorphous. The optimized surface structures of the B, C and D models have the similar geometric character as the tetrahedron structure of SiO2 . Furthermore, the coalescence between the Si and O atoms of the silicon oxide clusters includes significant ionic bond and certain covalent bond as shown by employing the Mulliken population analysis and the graphics of electron localization function.