Adsorbate-induced reconstruction by C 60 on close-packed metal surfaces : Mechanism for different types of reconstruction

Recent studies reveal that reconstruction of close-packed metal surfaces induced by C ₆₀ adsorption is the rule rather than the exception. Two types of reconstruction are reported for C ₆₀ on different surfaces: (1) C ₆₀ sinks into a 7-atom hole, such as on Cu(111); and (2) C ₆₀ sits over a 1-atom hole, such as on Ag(111) and Pt(111). An explanation for the preferred reconstruction type for different metals has been lacking. Here, we propose a criterion that predicts which reconstruction type should be expected: Namely, the formation of a 1- or 7-atom hole is determined only by the substrate geometric structure, including the surface lattice constant and the interlayer spacing; remarkably, the reconstruction type appears not to depend on the substrate electronic structure. Our intuitive geometrical explanation is validated by comparative first-principles calculations of the energetics of C ₆₀ on Cu(111), Ru(0001), Pt(111), and Ag(111) surfaces, listed here with increasing surface lattice constant. This provides a uniform explanation for the different reconstruction types that are observed experimentally for C ₆₀ on different close-packed metal surfaces. Moreover, our results provide a better explanation for the decomposition behavior of C ₆₀ on Ru(0001). © 2012 American Physical Society.