Sam Shallcross

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We explore the consequences of a rotation between graphene layers for the electronic spectrum. We derive the commensuration condition in real space and show that the interlayer electronic coupling is governed by an equivalent commensuration in reciprocal space. The larger the commensuration cell, the weaker the interlayer coupling, with exact decoupling for(More)
S. Sharma,1,2,* S. Pittalis,2 S. Kurth,2 S. Shallcross,3 J. K. Dewhurst,4 and E. K. U. Gross2 1Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany 2Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany 3Department of Physics, Technical University of Denmark, Building 307,(More)
In spin crossover phenomena, the magnetic moment of a molecule is switched by external means. Here we theoretically predict that several 5d-transition metals (TMs) adsorbed on finite graphene flakes undergo a spin crossover, resulting from multiple adsorption minima, that are absent in the zero-dimensional limit of benzene and the two-dimensional limit of(More)
A description of noncollinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective Kohn-Sham scalar potential and magnetic field are derived within the optimized effective potential (OEP) framework. With(More)
Charge transport at the Dirac point in bilayer graphene exhibits two dramatically different transport states, insulating and metallic, that occur in apparently otherwise indistinguishable experimental samples. We demonstrate that the existence of these two transport states has its origin in an interplay between evanescent modes, that dominate charge(More)
S. Shallcross,1,2,* L. Nordström,3 and S. Sharma4,5 1Lehrstuhl für Theoretische Festkörperphysik, Staudstrasse 7-B2, 91058 Erlangen, Germany 2Department of Physics, Technical University of Denmark, Building 307, DK-2800 Kongens Lyngby, Denmark 3Department of Physics, Condensed Matter Theory Group, Box 530, SE-751 21 Uppsala, Sweden 4Fritz Haber Institute of(More)
We apply the bootstrap kernel within time-dependent density functional theory to study the one-dimensional chain of polymer polyphenylenevinylene and molecular crystals of picene and pentacene. The absorption spectra of poly(p-phenylenevinylene) has a bound excitonic peak that is well-reproduced. Pentacene and picene, electronically similar materials, have(More)
The creation of magnetic storage devices by decoration of a graphene sheet by magnetic transition-metal adatoms, utilizing the high in-plane versus out-of-plane magnetic anisotropy energy (MAE), has recently been proposed. This concept is extended in our density-functional-based modeling study by incorporating the influence of the graphene edge on the MAE.(More)