摘要
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.
First principle calculations based on DFT have been applied to study various properties of rutile （110） surface. We used a nine-layer slab model with stoichiometric formula of TiO2 and the vacuum length of the cell fixed at 1.5 nm. The interactions between ionic core and valence electrons were represented by pesudopotentials. After analyzing the results, we found that an admixture bonding states existed in titanium dioxide： a stronger ionic bond accompanied by a weaker covalent bond between Ti and O. STM（Scanning tunneling microscope）image of Rutile （110） surface has been successfully simulated by DFT calculations, which was in accord with the Tersoff-Hamann＇s theory. A positive basis voltage of 2V was added to simulate STM experimentd conditions in imaging process. The distance between tip and surface were also changed step by step. By analyzing the electron density map and DOS plot, it is clear that electron factors dominated the STM image of rutile （110） surface and the jut in the image corresponded to 5-coordinated Ti atom rather than the bridge oxygen on the top.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第6期3769-3774,共6页
Acta Physica Sinica
基金
国家自然科学基金(批准号:50361003)
云南省自然科学基金重点项目(批准号:2006E003Z)资助的课题~~
