Now showing items 1-20 of 51

    • (2×2) Reconstructions of the {111} Polar Surfaces of GaAs 

      Kaxiras, Efthimios; Bar-Yam, Yaneer; Joannopoulos, John D.; Pandey, K.C. (American Physical Society, 1986)
      Ab initio total-energy calculations were used to examine (2×2) reconstruction models for the (111) and (1¯1¯1¯) surfaces of GaAs. For the (111) surface the lowest-energy Ga-vacancy geometry is determined; several mechanisms ...
    • Ab Initio Theory of Polar Semiconductor Surfaces. I. Methodology and the (22) Reconstructions of GaAs(111) 

      Kaxiras, Efthimios; Bar-Yam, Yaneer; Joannopoulos, John D.; Pandey, K.C. (American Physical Society, 1987)
      A methodology is developed for the theoretical study of the polar surfaces of compound semiconductors. It is based on the calculation of the total energy in the context of density-functional theory in the pseudopotential ...
    • Ab Initio Theory of Polar Semiconductor surfaces. II. (2x2) Reconstructions and Related Phase Transitions of GaAs(1¯1¯1¯) 

      Kaxiras, Efthimios; Bar-Yam, Yaneer; Joannopoulos, John D.; Pandey, K.C. (American Physical Society, 1987)
      The (2×2) reconstructions of GaAs(1¯ 1¯ 1¯) are studied with use of a theoretical approach based on the calculation of the total energy in the context of density-functional theory and the pseudopotential approximation. New ...
    • Ab initiotight-binding Hamiltonian for transition metal dichalcogenides 

      Fang, Shiang; Kuate Defo, Rodrick; Shirodkar, Sharmila N.; Lieu, Simon; Tritsaris, Georgios; Kaxiras, Efthimios (American Physical Society (APS), 2015)
      We present an accurate ab initio tight-binding Hamiltonian for the transition metal dichalcogenides, MoS2, MoSe2, WS2, WSe2, with a minimal basis (the d orbitals for the metal atoms and p orbitals for the chalcogen atoms) ...
    • The Amorphous-Crystal Interface in Silicon: a Tight-Binding Simulation 

      Bernstein, Noam; Aziz, Michael; Kaxiras, Efthimios (The American Physical Society, 1998)
      The structural features of the interface between the cystalline and amorphous phases of Si solid are studied in simulations based on a combination of empirical interatomic potentials and a nonorthogonal tight-binding model. ...
    • Atomistic Features of the Amorphous-Crystal Interface in Silicon 

      Kaxiras, Efthimios; Bernstien, Noam; Aziz, Michael (Springer Verlag, 1998)
      We simulate the amorphous-crystal interface in silicon using a combination of interatomic potential molecular-dynamics and tight-binding conjugate-gradient relaxation. The samples we create have high quality crystalline ...
    • Bounds on nanoscale nematicity in single-layerFeSe/SrTiO3 

      Huang, Dennis; Webb, Tatiana A.; Fang, Shiang; Song, Can-Li; Chang, Cui-Zu; Moodera, Jagadeesh S.; Kaxiras, Efthimios; Hoffman, Jennifer Eve (American Physical Society (APS), 2016)
      We use scanning tunneling microscopy (STM) and quasiparticle interference (QPI) imaging to investigate the low-energy orbital texture of single-layer FeSe/SrTiO3. We develop a T -matrix model of multiorbital QPI to disentangle ...
    • The Classical-Quantum Correspondence of Polyatomic Molecules 

      Pittman, Suzanne Michelle (2016-05-10)
      In this thesis, we study the classical-quantum correspondence of polyatomic molecules to further understand their rotational and vibrational behavior. More specifically, we focus on two different scenarios: (1) completely ...
    • Compositional Tuning of Ultrathin Surface Oxides on Metal and Alloy Substrates Using Photons: Dynamic Simulations and Experiments 

      Chang, Chia-Lin; Sankaranarayanan, Subramanian K. R. S.; Ruzmetov, Dmitry; Engelhard, Mark H.; Kaxiras, Efthimios; Ramanathan, Shriram (American Physical Society, 2010)
      We report on the ability to modify the structure and composition of ultrathin oxides grown on Ni and Ni-Al alloy surfaces at room temperature utilizing photon illumination. We find that the nickel-oxide formation is enhanced ...
    • Computational Caches 

      Waterland, Amos; Angelino, Elaine Lee; Cubuk, Ekin Dogus; Kaxiras, Efthimios; Adams, Ryan Prescott; Appavoo, Jonathan; Seltzer, Margo I. (ACM Press, 2013)
      Caching is a well-known technique for speeding up computation. We cache data from file systems and databases; we cache dynamically generated code blocks; we cache page translations in TLBs. We propose to cache the act of ...
    • Direct Imaging of Atomic-Scale Ripples in Few-Layer Graphene 

      Wang, Wei Li; Bhandari, Sagar; Yi, Wei; Bell, David C.; Westervelt, Robert M.; Kaxiras, Efthimios (American Chemical Society, 2012)
      Graphene has been touted as the prototypical two-dimensional solid of extraordinary stability and strength. However, its very existence relies on out-of-plane ripples as predicted by theory and confirmed by experiments. ...
    • Direct Observation of a Long-Lived Single-Atom Catalyst Chiseling Atomic Structures in Graphene 

      Wang, Wei Li; Santos, Elton J. G.; Jiang, Bin; Cubuk, Ekin Dogus; Ophus, Colin; Centeno, Alba; Pesquera, Amaia; Zurutuza, Amaia; Ciston, Jim; Westervelt, Robert M.; Kaxiras, Efthimios (American Chemical Society (ACS), 2014)
      Fabricating stable functional devices at the atomic scale is an ultimate goal of nanotechnology. In biological processes, such high-precision operations are accomplished by enzymes. A counterpart molecular catalyst that ...
    • Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1×2) 

      Hiebel, Fanny; Montemore, Matthew; Kaxiras, Efthimios; Friend, Cynthia M. (Elsevier BV, 2016)
      The Au(110) surface offers unique advantages for atomically-resolved model studies of catalytic oxidation processes on gold. We investigate the adsorption of oxygen on Au(110) using a combination of scanning tunneling ...
    • Dumbbell Defects in FeSe Films: A Scanning Tunneling Microscopy and First-Principles Investigation 

      Huang, Dennis; Webb, Tatiana A.; Song, Can-Li; Chang, Cui-Zu; Moodera, Jagadeesh S.; Kaxiras, Efthimios; Hoffman, Jennifer Eve (American Chemical Society (ACS), 2016)
      The properties of iron-based superconductors (Fe-SCs) can be varied dramatically with the introduction of dopants and atomic defects. As a pressing example, FeSe, parent phase of the highest-Tc Fe-SC, exhibits prevalent ...
    • Electric-Field Control of Magnetism in Graphene Quantum Dots: Ab Initio Calculations 

      Agapito, Luis A.; Kioussis, Nicholas; Kaxiras, Efthimios (American Physical Society, 2010)
      Employing ab initio calculations we predict that the magnetic states of hydrogenated diamond-shaped zigzag graphene quantum dots (GQDs), each exhibiting unique electronic structure, can be selectively tuned with gate ...
    • Electron and Hole Dynamics in Dye-Sensitized Solar Cells: Influencing Factors and Systematic Trends 

      Meng, Sheng; Kaxiras, Efthimios (American Chemical Society (ACS), 2010)
      We investigate electron and hole dynamics upon photon excitation in dye-sensitized solar cells, using a recently developed method based on real-time evolution of electronic states through time-dependent density functional ...
    • Electron-phonon interaction in ultrasmall-radius carbon nanotubes 

      Barnett, Ryan; Demler, Eugene A.; Kaxiras, Efthimios (American Physical Society (APS), 2005)
      We perform analysis of the band structure, phonon dispersion, and electron-phonon interactions in three types of small-radius carbon nanotubes. We find that the s5,5d nanotube can be described well by the zonefolding method ...
    • Embrittlement of Metal by Solute Segregation-Induced Amorphization 

      Chen, Hsiu-Pin; Kalia, Rajiv K.; Kaxiras, Efthimios; Lu, Gang; Nakano, Aiichiro; Nomura, Ken-ichi; van Duin, Adri C. T.; Vashishta, Priya; Yuan, Zaoshi (American Physical Society, 2010)
      Impurities segregated to grain boundaries of a material essentially alter its fracture behavior. A prime example is sulfur segregation-induced embrittlement of nickel, where an observed relation between sulfur-induced ...
    • Energetics of Defects and Diffusion Mechanisms in Graphite 

      Kaxiras, Efthimios; Pandey, K.C. (American Physical Society, 1988)
      Extensive first-principles calculations are presented for the formation energies and migration barriers of elementary defects in graphite, as well as for the activation energy of atomic exchange. The calculations show that ...
    • Epitaxial Growth of Molecular Crystals on van der Waals Substrates for High-Performance Organic Electronics 

      Lee, Chul-Ho; Schiros, Theanne; Santos, Elton J. G.; Kim, Bumjung; Yager, Kevin G.; Kang, Seok Ju; Lee, Sunwoo; Yu, Jaeeun; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Kaxiras, Efthimios; Nuckolls, Colin; Kim, Philip (Wiley-VCH Verlag Berlin, 2014)
      Epitaxial van der Waals (vdW) heterostructures of organic and layered materials are demonstrated to create high-performance organic electronic devices. High-quality rubrene films with large single-crystalline domains are ...