Electronic structure of the (111) and (-1-1-1) surfaces of cubic BN: A local-density-functional ab initio study

We present ab initio local-density-functional electronic structure calculations for the (111) and (-1-1-1) surfaces of cubic BN. The energetically stable reconstructions, namely the N adatom, N3 triangle models on the (111), the (2x1), boron and nitrogen triangle patterns on the (-1-1-1) surface are investigated. Band structure and properties of the surface states are discussed in detail.Comment: 8 pages, 12 figure

The surface energy and stress of metals

We investigated surface properties of metals by performing first-principles calculations. A systematic database was established for the surface relaxation, surface energy (gamma), and surface stress (tau) for metallic elements in the periodic table. The surfaces were modeled by multi-layered slab structures along the direction of low-index surfaces. The surface energy gamma of simple metals decreases as the atomic number increases in a given group, while the surface stress tau has its minimum in the middle. The transition metal series show parabolic trends for both gamma and tau with a dip in the middle. The dip occurs at half-band filling due to a long-range Friedel oscillation of the surface charge density, which induces a strong stability to the Peierls-like transition. In addition, due to magnetic effects, the dips in the 3d metal series are shallower and deeper for gamma and tau respectively, than those of the 4d and 5d metals. The surface stress of the transition metals is typically positive, only Cr and Mn have a negative tau for the (100) surface facet, indicating that they are under compression. The light actinides have an increasing gamma trend according to the atomic number. The present work provides a useful and consistent database for the theoretical modelling of surface phenomena

First Principles Study of the Binding of 4d and 5d Transition Metals to Graphene

We study the strength of the binding of 4d and 5d transition metals on a graphene sheet in the limit of high-coverage using first principles density functional theory. A database of the binding energies is presented. Our results show that the elements with low or near-half occupation of the d shell bind strongest to the graphene sheet. We find a transfer of electrons from the transition metal to the graphene sheet; the charge transfer decreases with increasing d shell occupation. Motivated by the strong binding to Hf we also study the binding of graphene to the Hf rich surface of HfO2. The predicted binding energy of −0.18 eV per C atom when coupled with the existing integration of HfO2 into Si-based CMOS devices suggests a new route to integrating graphene with silicon, allowing for an integration of graphene-based nanoelectronic components into existing silicon-based technology