Indium-Gallium Segregation in CulnxGa1-xSe2: An Ab Initio Based Monte Carlo Study

in Physical Review Letters (2010), 105

Precursor mediated crystallization in suspensions of hard shperes

in Physical Review Letters (2010), 105

Three Detailed Fluctuation Theorems

in Physical Review Letters (2010), 104(9),

The total entropy production of a trajectory can be split into an adiabatic and a nonadiabatic contribution, deriving, respectively, from the breaking of detailed balance via nonequilibrium boundary ... [more ▼]

The total entropy production of a trajectory can be split into an adiabatic and a nonadiabatic contribution, deriving, respectively, from the breaking of detailed balance via nonequilibrium boundary conditions or by external driving.We show that each of them, the total, the adiabatic, and the nonadiabatic trajectory entropy, separately satisfies a detailed fluctuation theorem. [less ▲]

Trails of Kilovolt Ions Created by Subsurface Channeling

in PHYSICAL REVIEW LETTERS (2010), 104(7),

Using scanning tunneling microscopy, we observe the damage trails produced by keV noble-gas ions incident at glancing angles onto Pt(111). Surface vacancies and adatoms aligned along the ion trajectory ... [more ▼]

Using scanning tunneling microscopy, we observe the damage trails produced by keV noble-gas ions incident at glancing angles onto Pt(111). Surface vacancies and adatoms aligned along the ion trajectory constitute the ion trails. Atomistic simulations reveal that these straight trails are produced by nuclear (elastic) collisions with surface layer atoms during subsurface channeling of the projectiles. In a small energy window around 5 keV, Xe(+) ions create vacancy grooves that mark the ion trajectory with atomic precision. The asymmetry of the adatom production on the two sides of the projectile path is traced back to the asymmetry of the ion's subsurface channel. [less ▲]

Accurate molecular van der Waals interactions from ground-state electron density and free-atom reference data

in Physical Review Letters (2009), 102(7),

We present a parameter-free method for an accurate determination of long-range van der Waals interactions from mean-field electronic structure calculations. Our method relies on the summation of ... [more ▼]

We present a parameter-free method for an accurate determination of long-range van der Waals interactions from mean-field electronic structure calculations. Our method relies on the summation of interatomic C6 coefficients, derived from the electron density of a molecule or solid and accurate reference data for the free atoms. The mean absolute error in the C6 coefficients is 5.5% when compared to accurate experimental values for 1225 intermolecular pairs, irrespective of the employed exchange-correlation functional. We show that the effective atomic C6 coefficients depend strongly on the bonding environment of an atom in a molecule. Finally, we analyze the van der Waals radii and the damping function in the C6R-6 correction method for density-functional theory calculations. © 2009 The American Physical Society. [less ▲]

Electron-electron correlation in graphite: A combined angle-resolved photoemission and first-principles study

in Physical Review Letters (2008), 100(3), 037601

The full three-dimensional dispersion of the pi bands, Fermi velocities, and effective masses are measured with angle-resolved photoemission spectroscopy and compared to first-principles calculations. The ... [more ▼]

The full three-dimensional dispersion of the pi bands, Fermi velocities, and effective masses are measured with angle-resolved photoemission spectroscopy and compared to first-principles calculations. The band structure by density-functional theory underestimates the slope of the bands and the trigonal warping effect. Including electron-electron correlation on the level of the GW approximation, however, yields remarkable improvement in the vicinity of the Fermi level. This demonstrates the breakdown of the independent electron picture in semimetallic graphite and points toward a pronounced role of electron correlation for the interpretation of transport experiments and double-resonant Raman scattering for a wide range of carbon based materials. [less ▲]

Suppression of Decoherence in Fast-Atom Diffraction at Surfaces

in Physical Review Letters (2008), 101(25),

Scattering of fast neutral atoms with keV kinetic energies at alkali-halide surfaces under grazing angles displays intriguing diffraction patterns. The surprisingly strong persistence of quantum coherence ... [more ▼]

Scattering of fast neutral atoms with keV kinetic energies at alkali-halide surfaces under grazing angles displays intriguing diffraction patterns. The surprisingly strong persistence of quantum coherence despite the impulsive interaction with an environment at solid state density and elevated temperatures raises fundamental questions such as to the suppression of decoherence and of the quantum-to-classical crossover. We present an ab initio simulation of the quantum diffraction of fast helium beams at a LiF (100) surface in the < 110 > direction and compare with recent experimental diffraction data. From the quantitative reconstruction of diffraction images the vertical LiF-surface reconstruction, or buckling, can be determined. [less ▲]

Hanbury Brown--Twiss Correlations and Noise in the Charge Transfer Statistics through a Multiterminal Kondo Dot

in Physical Review Letters (2007), 98

We analyze the charge transfer statistics through a quantum dot in the Kondo regime, when coupled to an arbitrary number of terminals N. Special attention is paid to current cross correlations between ... [more ▼]

We analyze the charge transfer statistics through a quantum dot in the Kondo regime, when coupled to an arbitrary number of terminals N. Special attention is paid to current cross correlations between concurring transport channels, which show distinct Hanbury Brown?Twiss antibunching for N>2 reflecting the fermionic nature of charge carriers. While this effect weakens as one moves away from the Kondo fixed point, a new type of correlations between nonconcurring channels emerges which are due entirely to the virtual polarization of the Kondo singlet. As these are not obscured by the background from fixed-point correlations they provide a promising means for extracting information on the parameters of the underlying Fermi-liquid model from the experimental data. [less ▲]

Depletion-induced percolation in networks of nanorods

in Physical Review Letters (2007), 98(10),

Excitons in boron nitride nanotubes: Dimensionality effects

in Physical Review Letters (2006), 96(12), 126104

We show that the optical absorption spectra of boron nitride (BN) nanotubes are dominated by strongly bound excitons. Our first-principles calculations indicate that the binding energy for the first and ... [more ▼]

We show that the optical absorption spectra of boron nitride (BN) nanotubes are dominated by strongly bound excitons. Our first-principles calculations indicate that the binding energy for the first and dominant excitonic peak depends sensitively on the dimensionality of the system, varying from 0.7 eV in bulk hexagonal BN via 2.1 eV in the single sheet of BN to more than 3 eV in the hypothetical (2,2) tube. The strongly localized nature of this exciton dictates the fast convergence of its binding energy with increasing tube diameter towards the sheet value. The absolute position of the first excitonic peak is almost independent of the tube radius and system dimensionality. This provides an explanation for the observed "optical gap" constancy for different tubes and bulk hexagonal BN. [less ▲]