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采用密度泛函理论从头计算了金红石型TiO2(110)表面的相关性质,切片模型含有9层原子,采用化学整比表面结构,晶胞真空层厚度为1·5nm,原子价电子采用超软赝势表达.差分电子密度分布图发现原子附近区域电子密度分布以球对称为主,电子定域形成离子键的趋势较强,但在Ti和O原子之间存在较弱的共价键.模拟了金红石型TiO2(110)表面结构的扫描隧道显微镜(scanning tunneling microscope,简称STM)图像,利用Tersoff-Hamann的成像理论,在+2V的正向偏压下,采用一系列变化的数值作为STM探针离表面桥式氧的距离,分析了相关态密度的变化,发现(110)表面的STM形貌凸起部分来自于5—Ti原子,而不是2—O原子(桥式氧),在TiO2(110)表面结构成像中,电子效应起主导作用,证实了STM实验观察到的亮行是Ti原子的结果.
The related properties of the surface of rutile TiO2 (110) were calculated by using density functional theory. The slice model contains 9 layers of atoms. The surface area of the layer is 1.5 nm. The atomic valence electrons are super soft The distribution of electron density shows that the distribution of electron density in the vicinity of the atom is dominated by the spherical symmetry, and the ionic bond tends to be stronger by electron localization, but weaker the covalent bond exists between Ti and O atoms. A scanning tunneling microscope (STM) image of the rutile TiO2 (110) surface structure was used. Using the Tersoff-Hamann imaging theory, a series of varying values were taken as the STM probe at +2 V forward bias It is found that the convex part of the STM morphology of (110) surface comes from the 5-Ti atom instead of the 2-O atom (bridge oxygen) 110) surface structure imaging, the electronic effect played a leading role, confirming the bright line observed by the STM experiment is the result of Ti atoms.