fig3

Figure 3. Top and side views of (A) on-top, (B) bridge and (C) hollow-HCP surface microstructures in a 3 × 4 × 4 slab, where atoms with different colors denote different regions. (D) Top view for adsorption configurations for different chemical species on a representative HEA FCC (111) surface. Atoms belonging to the top surface layer are labeled with a cross. Bonds between adsorbates and metal atoms are shown as red lines. Parameterization of the surface configurations is achieved using nearest neighbors. (E) OH* on-top binding. Each colored zone represents a set of three parameters. Orange (1): binding site. Light green (2): surface neighbors singly coordinated to binding site. Light gray (3): subsurface neighbors singly coordinated to binding site. (F) O* FCC hollow site binding. Each colored zone represents a set of five parameters, except for zone 1, where the set is 35 parameters. Zones 1-3 as in (E) and additionally dark green (4): surface neighbors doubly coordinated to binding site. Dark gray (5): subsurface neighbors doubly coordinated to binding site. (A-C) Reproduced with permission^[53]. Copyright 2021, American Chemical Society. (D) Reproduced with permission^[56]. Copyright 2021, American Chemical Society. (E) and (F) Reproduced with permission^[60]. Copyright 2019, Elsevier. HCP: hexagonal-closed packed; FCC: face-centered cubic; HEA: high-entropy alloy.