Sun Y Y, Xu H, Feng Y P, Huan A C H, Wee A T S
Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
Phys Rev Lett. 2004 Sep 24;93(13):136102. doi: 10.1103/PhysRevLett.93.136102. Epub 2004 Sep 21.
We present a clear and simple rule for determining the relaxation sequences on open (stepped, vicinal, or high-Miller-index) metal surfaces. At the bulk-truncated configuration of a surface, a surface slab is defined where the coordination of atoms is reduced from the bulk. The rule predicts that the interlayer spacings within this slab contract, while the interlayer spacing between this slab and the substrate expands. By first-principles calculations, we show that this rule is obeyed on all open Cu surfaces with interlayer spacings down to about 0.5 A. We also illustrate a direct relation of the relaxation sequences to the charge redistribution on these surfaces, which is demonstrated to be driving the multilayer relaxations. The applicability of the rule can be extended to other fcc and bcc metals, including unreconstructed and missing-row surfaces.
我们提出了一个清晰简单的规则，用于确定开放（阶梯状、邻位或高米勒指数）金属表面上的弛豫序列。在表面的体截断构型下，定义了一个表面平板，其中原子的配位数比体相减少。该规则预测，这个平板内的层间距会收缩，而这个平板与衬底之间的层间距会扩大。通过第一性原理计算，我们表明在所有层间距低至约0.5埃的开放铜表面上都遵循这一规则。我们还说明了弛豫序列与这些表面上电荷重新分布的直接关系，证明这种电荷重新分布驱动了多层弛豫。该规则的适用性可以扩展到其他面心立方和体心立方金属，包括未重构和缺失行的表面。
