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采用基于密度泛函理论的第一性原理方法对IrO_2(110)表面几何和电子结构进行了计算。结果表明,弛豫后,表层的五配位Ir原子和二配位的氧原子(桥氧)相对于理想表面向体相方向移动,而六配位的Ir原子和三配位的O原子向真空方向弛豫。表面原子弛豫不仅导致表层结构的变化,而且使表层的电子结构发生变化。从表面态密度分布可知,对表面电子结构造成主要影响的是最外三层原子。同时,由构型的(010)平面的电荷密度分布可知相邻层间存在着强烈的Ir-O共价键作用;由于电荷在真空层的消耗和在第一、二原子层间的积累,导致最外原子层间距的减小,相应的Ir-O化学键得到增强。计算得到该IrO_2(110)面的表面能大小为1.434 J·m~(-2)。
The geometrical and electronic structures of IrO_2 (110) surface were calculated by the first principle method based on density functional theory. The results show that after relaxation, the five-coordinated Ir atoms and the two-coordinated oxygen atoms (bridging oxygen) of the surface layer move toward the bulk direction relative to the ideal surface, whereas the six-coordinated Ir atoms and the three-coordinated O atoms move towards Vacuum direction relaxation. Surface atomic relaxation not only leads to changes in the surface structure, but also the surface of the electronic structure changes. From the surface state density distribution shows that the main impact on the surface electronic structure is the outermost three atoms. At the same time, there is a strong Ir-O covalent bond between adjacent layers due to the charge density distribution of the (010) plane. Due to the charge depletion in the vacuum layer and the accumulation between the first and second atomic layers, Resulting in the decrease of the distance between the outermost atomic layers and corresponding enhancement of the Ir-O chemical bond. The calculated surface energy of the IrO_2 (110) surface is 1.434 J · m -2.