References of "Physical Review Letters"
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See detailInelastic Electron Backscattering in a Generic Helical Edge Channel
Schmidt, Thomas UL; Rachel, Stephan; von Oppen, Felix et al

in Physical Review Letters (2012), 108

We evaluate the low-temperature conductance of a weakly interacting one-dimensional helical liquid without axial spin symmetry. The lack of that symmetry allows for inelastic backscattering of a single ... [more ▼]

We evaluate the low-temperature conductance of a weakly interacting one-dimensional helical liquid without axial spin symmetry. The lack of that symmetry allows for inelastic backscattering of a single electron, accompanied by forward scattering of another. This joint effect of weak interactions and potential scattering off impurities results in a temperature-dependent deviation from the quantized conductance, $ G T^4$. In addition, $ G$ is sensitive to the position of the Fermi level. We determine numerically the parameters entering our generic model for the Bernevig-Hughes-Zhang Hamiltonian of a HgTe/CdTe quantum well in the presence of Rashba spin-orbit coupling. [less ▲]

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See detailAccurate and Efficient Method for Many-Body van der Waals Interactions
Tkatchenko, Alexandre UL; DiStasio, Jr; Car, Roberto et al

in PHYSICAL REVIEW LETTERS (2012), 108(23),

An efficient method is developed for the microscopic description of the frequency-dependent polarizability of finite-gap molecules and solids. This is achieved by combining the Tkatchenko-Scheffler van ... [more ▼]

An efficient method is developed for the microscopic description of the frequency-dependent polarizability of finite-gap molecules and solids. This is achieved by combining the Tkatchenko-Scheffler van der Waals (vdW) method [Phys. Rev. Lett. 102, 073005 (2009)] with the self-consistent screening equation of classical electrodynamics. This leads to a seamless description of polarization and depolarization for the polarizability tensor of molecules and solids. The screened long-range many-body vdW energy is obtained from the solution of the Schrodinger equation for a system of coupled oscillators. We show that the screening and the many-body vdW energy play a significant role even for rather small molecules, becoming crucial for an accurate treatment of conformational energies for biomolecules and binding of molecular crystals. The computational cost of the developed theory is negligible compared to the underlying electronic structure calculation. [less ▲]

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See detailReply to Comment on Fast and Accurate Modeling of Molecular Atomization Energies with Machine Learning
Rupp, M.; Tkatchenko, Alexandre UL; Müller, K.-R. et al

in Physical Review Letters (2012), 109(5),

[No abstract available]

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See detailUnraveling the stability of polypeptide helices: Critical role of van der Waals interactions
Tkatchenko, Alexandre UL; Rossi, M.; Blum, V. et al

in Physical Review Letters (2011), 106(11),

Folding and unfolding processes are important for the functional capability of polypeptides and proteins. In contrast with a physiological environment (solvated or condensed phases), an in vacuo study ... [more ▼]

Folding and unfolding processes are important for the functional capability of polypeptides and proteins. In contrast with a physiological environment (solvated or condensed phases), an in vacuo study provides well-defined "clean room" conditions to analyze the intramolecular interactions that largely control the structure, stability, and folding or unfolding dynamics. Here we show that a proper consideration of van der Waals (vdW) dispersion forces in density-functional theory (DFT) is essential, and a recently developed DFT+vdW approach enables long time-scale ab initio molecular dynamics simulations at an accuracy close to "gold standard" quantum-chemical calculations. The results show that the inclusion of vdW interactions qualitatively changes the conformational landscape of alanine polypeptides, and greatly enhances the thermal stability of helical structures, in agreement with gas-phase experiments. © 2011 American Physical Society. [less ▲]

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See detailNematic-smectic transition under confinement in liquid crystalline colloidal shells
Liang, Hsin-Ling; Schymura, Stefan; Rudquist, Per et al

in Physical Review Letters (2011), 106(24), 247801

We carry out the first study of smectic liquid crystalline colloidal shells and investigate how their complex internal structure depends on the director configuration in the nematic phase, preceding the ... [more ▼]

We carry out the first study of smectic liquid crystalline colloidal shells and investigate how their complex internal structure depends on the director configuration in the nematic phase, preceding the smectic phase on cooling. Differences in the free energy cost of director bend and splay give an initial skewed distribution of topological defects in the nematic phase. In the smectic phase, the topological and geometrical constraints of the spherical shell imposed on the developing 1D quasi-long-range order create a conflict that triggers a series of buckling instabilities. Two different characteristic defect patterns arise, one driven by the curvature of the shell, the other by the strong nonuniformities in the director field in the vicinity of the topological defects. [less ▲]

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See detailBeyond the random-phase approximation for the electron correlation energy: The importance of single excitations
Ren, X.; Tkatchenko, Alexandre UL; Rinke, P. et al

in Physical Review Letters (2011), 106(15),

The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density ... [more ▼]

The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice-evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals-leads to a systematic underbinding of molecules and solids. Here we demonstrate that this behavior can be corrected by adding a "single excitation" contribution, so far not included in the standard RPA scheme. A similar improvement can also be achieved by replacing the non-self-consistent EX total energy by the corresponding self-consistent Hartree-Fock total energy, while retaining the RPA correlation energy evaluated using KS orbitals. Both schemes achieve chemical accuracy for a standard benchmark set of noncovalent intermolecular interactions. © 2011 American Physical Society. [less ▲]

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See detailVan der Waals interactions in ionic and semiconductor solids
Zhang, G.-X.; Tkatchenko, Alexandre UL; Paier, J. et al

in Physical Review Letters (2011), 107(24),

Van der Waals (vdW) energy corrected density-functional theory is applied to study the cohesive properties of ionic and semiconductor solids (C, Si, Ge, GaAs, NaCl, and MgO). The required polarizability ... [more ▼]

Van der Waals (vdW) energy corrected density-functional theory is applied to study the cohesive properties of ionic and semiconductor solids (C, Si, Ge, GaAs, NaCl, and MgO). The required polarizability and dispersion coefficients are calculated using the dielectric function obtained from time-dependent density-functional theory. Coefficients for "atoms in the solid" are then calculated from the Hirshfeld partitioning of the electron density. It is shown that the Clausius-Mossotti equation that relates the polarizability and the dielectric function is accurate even for covalently-bonded semiconductors. We find an overall improvement in the cohesive properties of Si, Ge, GaAs, NaCl, and MgO, when vdW interactions are included on top of the Perdew-Burke- Ernzerhof or Heyd-Scuseria-Ernzerhof functionals. The relevance of our findings for other solids is discussed. © 2011 American Physical Society. [less ▲]

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See detailHydrogen bonds and van der Waals forces in ice at ambient and high pressures
Santra, B.; Klimeš, J.; Alfè, D. et al

in Physical Review Letters (2011), 107(18),

The first principles methods, density-functional theory and quantum Monte Carlo, have been used to examine the balance between van der Waals (vdW) forces and hydrogen bonding in ambient and high-pressure ... [more ▼]

The first principles methods, density-functional theory and quantum Monte Carlo, have been used to examine the balance between van der Waals (vdW) forces and hydrogen bonding in ambient and high-pressure phases of ice. At higher pressure, the contribution to the lattice energy from vdW increases and that from hydrogen bonding decreases, leading vdW to have a substantial effect on the transition pressures between the crystalline ice phases. An important consequence, likely to be of relevance to molecular crystals in general, is that transition pressures obtained from density-functional theory exchange-correlation functionals which neglect vdW forces are greatly overestimated. © 2011 American Physical Society. [less ▲]

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See detailCurrent Correlations in Quantum Spin Hall Insulators
Schmidt, Thomas UL

in Physical Review Letters (2011), 107

We consider a four-terminal setup of a two-dimensional topological insulator (quantum spin Hall insulator) with local tunneling between the upper and lower edges. The edge modes are modeled as helical ... [more ▼]

We consider a four-terminal setup of a two-dimensional topological insulator (quantum spin Hall insulator) with local tunneling between the upper and lower edges. The edge modes are modeled as helical Luttinger liquids and the electron-electron interactions are taken into account exactly. Using perturbation theory in the tunneling, we derive the cumulant generating function for the inter-edge current. We show that different possible transport channels give rise to different signatures in the current noise and current cross-correlations, which could be exploited in experiments to elucidate the interplay between electron-electron interactions and the helical nature of the edge states. [less ▲]

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See detailTrails of Kilovolt Ions Created by Subsurface Channeling
Redinger, Alex UL; Standop, Sebastian; Michely, Thomas et al

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 ▲]

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See detailLarge Neutral Barrier at Grain Boundaries in Chalcopyrite Thin Films
Hafemeister, Michael; Siebentritt, Susanne UL; Albert, Jürgen et al

in Physical Review Letters (2010), 104(196602), 1-4

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See detailEfficiency at Maximum Power of Low-Dissipation Carnot Engines
Esposito, Massimiliano UL; Kawai, Ryoichi; Lindenberg, Katja et al

in Physical Review Letters (2010), 105(15),

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See detailThree Detailed Fluctuation Theorems
Esposito, Massimiliano UL; Van den Broeck, Christian

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 ▲]

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See detailIndium-Gallium Segregation in CulnxGa1-xSe2: An Ab Initio Based Monte Carlo Study
Ludwig, Christian D. R.; Gruhn, Thomas; Felser, Claudia et al

in Physical Review Letters (2010), 105

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See detailStacking and registry effects in layered materials: The case of hexagonal boron nitride
Marom, N.; Bernstein, J.; Garel, J. et al

in Physical Review Letters (2010), 105(4),

The interlayer sliding energy landscape of hexagonal boron nitride (h-BN) is investigated via a van der Waals corrected density functional theory approach. It is found that the main role of the van der ... [more ▼]

The interlayer sliding energy landscape of hexagonal boron nitride (h-BN) is investigated via a van der Waals corrected density functional theory approach. It is found that the main role of the van der Waals forces is to anchor the layers at a fixed distance, whereas the electrostatic forces dictate the optimal stacking mode and the interlayer sliding energy. A nearly free-sliding path is identified, along which band gap modulations of ∼0.6eV are obtained. We propose a simple geometric model that quantifies the registry matching between the layers and captures the essence of the corrugated h-BN interlayer energy landscape. The simplicity of this phenomenological model opens the way to the modeling of complex layered structures, such as carbon and boron nitride nanotubes. © 2010 The American Physical Society. [less ▲]

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See detailPrecursor mediated crystallization in suspensions of hard shperes
Schilling, Tanja UL; Schöpe, H. J.; Oettel, M. et al

in Physical Review Letters (2010), 105

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See detailFate of 1D Spin-Charge Separation Away from Fermi Points
Schmidt, Thomas UL; Imambekov, Adilet; Glazman, Leonid I.

in Physical Review Letters (2010), 104

We consider the dynamic response functions of interacting one dimensional spin-$1/2$ fermions at arbitrary momenta. We build a nonperturbative zero-temperature theory of the threshold singularities using ... [more ▼]

We consider the dynamic response functions of interacting one dimensional spin-$1/2$ fermions at arbitrary momenta. We build a nonperturbative zero-temperature theory of the threshold singularities using mobile impurity Hamiltonians. The interaction induced low-energy spin-charge separation and power-law threshold singularities survive away from Fermi points. We express the threshold exponents in terms of the spinon spectrum. [less ▲]

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See detailDetection of qubit-oscillator entanglement in nanoelectromechanical systems
Schmidt, Thomas UL; Borkje; Bruder, Christoph et al

in Physical Review Letters (2010), 104

Experiments over the past years have demonstrated that it is possible to bring nanomechanical resonators and superconducting qubits close to the quantum regime and to measure their properties with an ... [more ▼]

Experiments over the past years have demonstrated that it is possible to bring nanomechanical resonators and superconducting qubits close to the quantum regime and to measure their properties with an accuracy close to the Heisenberg uncertainty limit. Therefore, it is just a question of time before we will routinely see true quantum effects in nanomechanical systems. One of the hallmarks of quantum mechanics is the existence of entangled states. We propose a realistic scenario making it possible to detect entanglement of a mechanical resonator and a qubit in a nanoelectromechanical setup. The detection scheme is all done by standard current and noise measurements of an atomic point contact coupled to an oscillator and a qubit. This setup could allow for the first observation of entanglement between a continuous and a discrete quantum system in the solid state. [less ▲]

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See detailUniversality of Efficiency at Maximum Power
Esposito, Massimiliano UL; Lindenberg, Katja; Van den Broeck, Christian

in Physical Review Letters (2009), 102(13),

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See detailRapid Coarsening of Ion Beam Ripple Patterns by Defect Annihilation
Hansen, Henri; Redinger, Alex UL; Messlinger, Sebastian et al

in PHYSICAL REVIEW LETTERS (2009), 102(14),

Ripple patterns formed on Pt(111) through grazing incidence ion beam erosion coarsen rapidly. At and below 450 K coarsening of the patterns is athermal and kinetic, unrelated to diffusion and surface free ... [more ▼]

Ripple patterns formed on Pt(111) through grazing incidence ion beam erosion coarsen rapidly. At and below 450 K coarsening of the patterns is athermal and kinetic, unrelated to diffusion and surface free energy. Similar to the situation for sand dunes, coarsening takes place through annihilation reactions of mobile defects in the pattern. The defect velocity derived on the basis of a simple model agrees quantitatively with the velocity of monatomic steps illuminated by the ion beam. [less ▲]

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