Publications by Efthimios Kaxiras

Qualitative link between work of adhesion and thermal conductance of metal/diamond interfaces

Ludger Weber, Christian Monachon, Georg Schusteritsch, Efthimios Kaxiras

We report Time-Domain ThermoReflectance experiments measuring the Thermal Boundary Conductance (TBC) of interfaces between diamond and metal surfaces, based on samples consisting of [111] diamond substrates with hydrogen or with sp2 carbon surface terminat ...

Amer Inst Physics2014

Structural Role of RKS Motifs in Chromatin Interactions: A Molecular Dynamics Study of HP1 Bound to a Variably Modified Histone Tail

Efthimios Kaxiras

The current understanding of epigenetic signaling assigns a central role to post-translational modifications that occur in the histone tails. In this context, it has been proposed that methylation of K9 and phosphorylation of S10 in the tail of histone H3 ...

2012

Multiscale Hemodynamics Using GPU Clusters

Efthimios Kaxiras

The parallel implementation of MUPHY, a concurrent multiscale code for large-scale hemodynamic simulations in anatomically realistic geometries, for multi-GPU platforms is presented. Performance tests show excellent results, with a nearly linear parallel s ...

Cambridge University Press2012

Theoretical investigation of the C-60/copper phthalocyanine organic photovoltaic heterojunction

Efthimios Kaxiras, Jun Ren, Sheng Meng

Molecular heterojunctions, such as the one based on copper phthalocyanine (CuPc) and carbon fullerene (C-60) molecules, are commonly employed in organic photovoltaic cells as electron donor-acceptor pairs. We have investigated the different atomic structur ...

2012

Design of Dye Acceptors for Photovoltaics from First-Principles Calculations

Michael Graetzel, Mohammad Khaja Nazeeruddin, Efthimios Kaxiras, Sheng Meng

We investigate a set of donor-pi-acceptor (D-pi-A) dyes with new acceptor groups for dye-sensitized solar cells, using time-dependent density-functional-theory calculations of the electronic structure and optical absorption. We considered three types of mo ...

American Chemical Society2011

D-pi-A Dye System Containing Cyano-Benzoic Acid as Anchoring Group for Dye-Sensitized Solar Cells

Michael Graetzel, Guido Rothenberger, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Takeru Bessho, Efthimios Kaxiras, Sheng Meng

A D-pi-A dye (KM-1) incorporating cyanobenzoic acid as a new acceptor/anchoring group has been synthesized for dye-sensitized solar cells (DSCs) with a high molar extinction coefficient of 66 700 M-1 cm(-1) at 437 nm. Theoretical calculations show that the ...

American Chemical Society2011

Influence of CH2 content and network defects on the elastic properties of organosilicate glasses

Efthimios Kaxiras, Han Li

Organosilicate glasses (OSGs) are used as low-k intermetal dielectrics for advanced integrated circuits. In this application, the material must fulfill two conflicting requirements: It has to have low density to reduce the dielectric constant while being s ...

2011

Properties of copper (fluoro-)phthalocyanine layers deposited on epitaxial graphene

Efthimios Kaxiras, Jun Ren, Sheng Meng

We investigate the atomic structure and electronic properties of monolayers of copper phthalocyanines (CuPc) deposited on epitaxial graphene substrate. We focus in particular on hexadecafluorophthalocyanine (F16CuPc), using both theoretical and experimenta ...

American Institute of Physics2011

Stiffening of organosilicate glasses by organic cross-linking

Efthimios Kaxiras, Han Li

Atomistic simulations show that organosilicates, used as low permittivity dielectric materials in advanced integrated circuits, can be made substantially stiffer than amorphous silica, while maintaining a lower mass density The enhanced stiffness is achiev ...

2011

Direct correlation of crystal structure and optical properties in wurtzite/zinc-blende GaAs nanowire heterostructures

Anna Fontcuberta i Morral, Martin Heiss, Emanuele Uccelli, Efthimios Kaxiras, Jun Ren, Sonia Conesa Boj

A method for the direct correlation at the nanoscale of structural and optical properties of single GaAs nanowires is reported. Nanowires consisting of 100% wurtzite and nanowires presenting zinc-blende/wurtzite polytypism are investigated by photoluminesc ...

2011

Electron and Hole Dynamics in Dye-Sensitized Solar Cells: Influencing Factors and Systematic Trends

Efthimios Kaxiras, Sheng Meng

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 theory. The systems we considered ...

American Chemical Society (ACS)2010

Optical properties of clusters and molecules from real-time time-dependent density functional theory using a self-consistent field

Efthimios Kaxiras, Jun Ren, Sheng Meng

We present a detailed study of optical absorption spectra of finite-size structures, using a method based on time-dependent density-functional theory (TDDFT), which involves a self-consistent field for the propagation of the Kohn-Sham wavefunctions in real ...

Taylor & Francis2010

Selective adsorption and electronic interaction of F16CuPc on epitaxial graphene

Efthimios Kaxiras, Jun Ren, Sheng Meng, Xi Chen

We investigate the electronic coupling between copper hexadecafluoro-phthalocyanine (F16CuPc) and epitaxial graphene (EG) on 6H-SiC (0001) using a combined approach of low-temperature scanning tunneling spectroscopy and electronic structure calculations. T ...

2010

Topological Frustration in Graphene Nanoflakes: Magnetic Order and Spin Logic Devices

Oleg Yazyev, Efthimios Kaxiras, Sheng Meng

Magnetic order in graphene-related structures can arise from size effects or from topological frustration. We introduce a rigorous classification scheme for the types of finite graphene structures (nanoflakes) which lead to large net spin or to antiferroma ...

2009

Comment on graphene nanoflakes with large spin: Broken-symmetry states

Oleg Yazyev, Efthimios Kaxiras, Sheng Meng

American Chemical Society (ACS)2008