铝和银在铱（111）宽范围吸附的稳定性、原子构型及电子特性研究

利用第一性原理密度泛函理论研究了铝和银在铱的111面的宽范围吸附特性。基于密度泛函理论计算了覆盖度在0.11ML到2.00ML的结构稳定性、原子构型及平均结合能。对于铝原子在铱111面的吸附，最稳定的结构是铝原子覆盖度为0.5ML位于密堆六方空位（hcp-hollow），相应的结合能为-4.68eV；对于亚层铝原子的吸附，最稳定结构是铝原子覆盖度为1.00ML时位于octahedral位置，相应的结合能为-5.28eV。对于覆盖度为2.00ML的满覆盖度混合结构的表层及亚层吸附，最稳定结构是Al位于六方密堆及八方密堆位置，相应的结合能为-4.70eV。这意味着当铝原子以满覆盖度吸附在铱的111面上时，趋向于在铱的111面的亚层形成化学键，而非吸附于表层。相比于铝吸附在铱111面，银的吸附特性呈现出很大的不同，面心位置更为稳定，在覆盖度为0.25ML时其结合能为3.89eV，略微高出密堆六方位置处3.88eV的结合能。

Stability, structure, and electronic properties of Aluminium and Silver adsorptions on Ir(111) at wide range coverage

Aluminium and silver adsorptions on Ir (111) at a large coverage are investigated by a first-principles approach. The stability, atomic geometry, average binding energy with the coverage from 0.11 monolayer (ML) to 2.00 ML are calculated by using density functional method. For pure on-surface aluminum adsorption on Ir (111), the most favorable structure is Al at hcp-hollow site at 0.50ML coverage with binding energy -4.68eV. For Al adsorption in pure sub-surface sites, the most stable is 1.00ML coverage at octahedral site with -5.28eV binding energy. For mix-structures at full monolayer 2.00ML both of on-surface and subsurface, hcp site plus octahedral site is the favorable site with binding energy -4.70eV, it means that Al likes to form aluminide compound in the sub-surface of Ir (111) instead of adsorbed on-surface. Compared with aluminum adsorption, silver adsorption shows very different properties, fcc site becomes more favorable, penetration of Ag atoms into the iridium crystal is difficult, Ag tends to grow on Ir(111) layer by layer.