Baker Thomas A, Friend Cynthia M, Kaxiras Efthimios
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
J Chem Phys. 2009 Feb 28;130(8):084701. doi: 10.1063/1.3077314.
We investigate the effects of Cl and O coverage on the atomic structure of the Au(111) surface using density functional theory calculations. We find that the release and incorporation of gold atoms in the adsorbate layer becomes energetically favorable only at high coverages of either O or Cl (>0.66 ML (monolayer) for O and >0.33 ML for Cl), whereas adsorption without the incorporation of gold is favorable at lower coverages. The bonding between the adsorbate and gold substrate changes significantly with coverage, becoming more covalent (less ionic) at higher Cl and O coverage. This is based on the fact that at higher coverages there is less ionic charge transfer to the adsorbate, while the electron density in the region between the adsorbate and a surface gold atom is increased. Our results illustrate that the O and Cl coverage on Au(111) can dramatically affect its structure and bonding, which are important features in any application of gold involving these adsorbates.
我们使用密度泛函理论计算研究了氯和氧覆盖度对Au(111)表面原子结构的影响。我们发现，只有在氧或氯的高覆盖度下（氧>0.66 ML（单层），氯>0.33 ML），吸附层中金原子的释放和掺入在能量上才变得有利，而在较低覆盖度下，不掺入金的吸附是有利的。吸附质与金基底之间的键合随覆盖度显著变化，在较高的氯和氧覆盖度下变得更具共价性（离子性更弱）。这是基于这样一个事实，即在较高覆盖度下，向吸附质的离子电荷转移较少，而吸附质与表面金原子之间区域的电子密度增加。我们的结果表明，Au(111)上的氧和氯覆盖度会显著影响其结构和键合，这在涉及这些吸附质的任何金应用中都是重要特征。
