Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden.
J Phys Condens Matter. 2011 Oct 5;23(39):395001. doi: 10.1088/0953-8984/23/39/395001. Epub 2011 Sep 2.
We performed a systematic density functional (DF) study of the adsorption of copper, silver, and gold adatoms on pristine graphene, especially accounting for van der Waals (vdW) interactions by the vdW-DF and PBE + D2 methods. In particular, we analyze the preferred adsorption site (among top, bridge, and hollow positions) together with the corresponding distortion of the graphene sheet and identify diffusion paths. Both vdW schemes show that the coinage metal atoms do bind to the graphene sheet and that in some cases the buckling of the graphene layer can be significant. Only the results for silver are qualitatively at variance with those obtained with the generalized gradient approximation, which gives no binding in this case. However in all three cases, we observe some quantitative differences between the vdW-DF and PBE + D2 methods. For instance the adsorption energies calculated with the PBE + D2 method are systematically higher than the ones obtained with vdW-DF. Moreover, the equilibrium distances computed with PBE + D2 are shorter than those calculated with the vdW-DF method.
我们使用系统的密度泛函（DF）方法研究了铜、银和金原子在原始石墨烯上的吸附，特别考虑了范德华（vdW）相互作用，使用了 vdW-DF 和 PBE + D2 方法。特别是，我们分析了优先吸附位置（在顶部、桥位和空位位置之间）以及相应的石墨烯片的变形，并确定了扩散路径。这两种 vdW 方案都表明，金属原子确实会与石墨烯片结合，并且在某些情况下，石墨烯层的翘曲可能会非常显著。只有银的结果与广义梯度近似（GGA）的结果定性上不一致，在这种情况下，广义梯度近似没有给出结合。然而，在所有三种情况下，我们都观察到 vdW-DF 和 PBE + D2 方法之间存在一些定量差异。例如，使用 PBE + D2 方法计算的吸附能系统地高于使用 vdW-DF 方法计算的吸附能。此外，使用 PBE + D2 计算的平衡距离比使用 vdW-DF 方法计算的平衡距离短。
