Patterson C H
School of Physics, Trinity College Dublin, Dublin 2, Ireland.
J Phys Condens Matter. 2015 Dec 2;27(47):475001. doi: 10.1088/0953-8984/27/47/475001. Epub 2015 Oct 13.
Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the [Formula: see text]-Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the [Formula: see text]-Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the [Formula: see text]-Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the [Formula: see text]-Au phase. Extra Au atoms bound in interstitial sites of the [Formula: see text]-Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a [Formula: see text]-Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the [Formula: see text]-Au structure. The [Formula: see text]-Au phase is 2D chiral and this is evident in computed and actual STM images. [Formula: see text]-Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si-Au top layers of the [Formula: see text]-Au and [Formula: see text]-Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given.
具有约一个金单层的硅（1 1 1）-金表面呈现出许多有序结构以及包含无序畴壁的结构。本文给出的杂化密度泛函理论（DFT）计算揭示了这些复杂结构的起源以及形成畴壁的趋势。[化学式：见原文]-金相的共轭蜂窝链三聚体（CHCT）结构包含具有非键合表面态的硅原子，这些硅原子可在CHCT结构的间隙中成对结合金原子并使该表面具有金属性。吸附在[化学式：见原文]-金表面的硅原子通过与非键合态相互作用诱导出一个带隙表面。在[化学式：见原文]-金表面的间隙位置吸附额外的金原子通过与非键合轨道相互作用而得以稳定，并导致包括[化学式：见原文]-金相在内的更高覆盖度有序结构。结合在[化学式：见原文]-金表面间隙位置的额外金原子导致顶层硅原子具有SiAu4蝶形翼构型。使用总能量最小化方法计算了[化学式：见原文]-金相的结构，其面内顶层原子层位置先前已通过电子全息技术确定（Grozea等人，1998年，《表面科学》418 32）。计算了该结构的帕特森函数，其与面内x射线衍射研究数据（Dornisch等人，1991年，《物理评论B》44 11221）吻合良好。计算了畴壁和[化学式：见原文]-金结构的填充态和空态扫描隧道显微镜（STM）图像。[化学式：见原文]-金相是二维手性的，这在计算得到的和实际的STM图像中都很明显。[化学式：见原文]-金和畴壁结构包含具有蝶形翼形状的SiAu4基序。分析了[化学式：见原文]-金和[化学式：见原文]-金表面的硅-金顶层内的化学键，并给出了SiAu4基序结构的解释。
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