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The unprecedented applications of two-dimensional (2D) atomic sheets in spintronics are formidably hindered by the lack of ordered spin structures. Here we present first-principles calculations demonstrating that the recently synthesized dimethylmethylene-bridged triphenylamine (DTPA) porous sheet is a ferromagnetic half-metal and that the size of the band gap in the semiconducting channel is roughly 1 eV, which makes the DTPA sheet an ideal candidate for a spin-selective conductor. In addition, the robust half-metallicity of the 2D DTPA sheet under external strain increases the possibility of applications in nanoelectric devices. In view of the most recent experimental progress on controlled synthesis, organic porous sheets pave a practical way to achieve new spintronics.

The electronic properties of a graphene–boron nitride (G/BN) bilayer have been carefully investigated by first-principles calculations. We find that the energy gap of graphene is tunable from 0 to 0.55 eV and sensitive to the stacking order and interlayer distances of the G/BN bilayer. By electronic structure analysis and tight-binding simulations, we conclude that the charge redistribution within graphene and charge transfer between graphene and BN layers determine the energy gap of graphene, through modification of the on-site energy difference of carbon p orbitals at two sublattices. On the basis of the revealed mechanism, we also predict how to engineer the band gap of graphene.

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A comparative study of the interaction of M (M ) Sc, Cu) atoms with small Si n (n ) 1-6) clusters is performed by means of a hybrid density functional technique (B3LYP) in conjunction with a 6-311+G(d) basis set. The structures identified for the most stable isomers of MSi n are usually different for M ) Sc and Cu, showing different growth patterns of these two clusters. Charge transfer is found to proceed from M to the Si n framework in all MSi n clusters and is stronger for M ) Sc than for M ) Cu. A mixed ionic and covalent bonding picture between M and Si atoms emerges for MSi n . Strong hybridization exists between Sc d and Si orbitals in ScSi n , while the d shell of Cu in CuSi n remains nearly closed and contributes little to the Cu-Si bonding. On the basis of the optimized geometries, various energetic properties are calculated for the most stable isomers of MSi n , including the binding and fragmentation energies, vertical and adiabatic ionization potentials, and electron affinities. Both the binding and fragmentation energies indicate that MSi 2 and MSi 5 have enhanced stability and could be produced with high abundance in mass spectrum.