First-principles studies on adsorbate-induced faceting of Re(1121)

Motivated by our recent scanning tunneling microscopy measurements on Re(1121) that, depending on the nature of the adsorbate, showed the formation of distinct facets when the substrate is annealed to elevated temperatures, we used density-functional theory to explore why faceting of Re(1121) induced by NH3 is different from that by O-2. Our calculations indicate that nitrogen adsorption causes two-sided ridges, combining (1342) and (3142) faces, to become thermodynamically favored at temperatures below 1080 K while oxygen adsorption below 1130 K leads to four-sided pyramids exhibiting (1010, (0110), (1011), and (0111) faces.