Figure 1: Unit cell geometry used to study the fcc(211) surface with a CO molecule bound to the atop site.
From: Mechanical work makes important contributions to surface chemistry at steps

(a), Model fcc(211) surface with CO molecule bound to the atop position at the step edge; (b), view of slab from the top; and right (c), view of slab from the side, those atoms marked ‘free’ are unconstrained and those marked ‘frozen’ are constrained in the positions determined by continuum elasticity.