@article{13548, author = {{Thissen, Peter and Thissen, Vera and Wippermann, Stefan and Chabal, Yves J. and Grundmeier, Guido and Schmidt, Wolf Gero}}, issn = {{0039-6028}}, journal = {{Surface Science}}, pages = {{902--907}}, title = {{{pH-dependent structure and energetics of H2O/MgO(100)}}}, doi = {{10.1016/j.susc.2012.01.018}}, volume = {{606}}, year = {{2012}}, } @article{13542, author = {{Thissen, Peter and Peixoto, Tatiana and Longo, Roberto C. and Peng, Weina and Schmidt, Wolf Gero and Cho, Kyeongjae and Chabal, Yves J.}}, issn = {{0002-7863}}, journal = {{Journal of the American Chemical Society}}, pages = {{8869--8874}}, title = {{{Activation of Surface Hydroxyl Groups by Modification of H-Terminated Si(111) Surfaces}}}, doi = {{10.1021/ja300270w}}, volume = {{134}}, year = {{2012}}, } @article{13543, author = {{Rauls, E. and Schmidt, Wolf Gero and Pertram, T. and Wandelt, K.}}, issn = {{0039-6028}}, journal = {{Surface Science}}, pages = {{1120--1125}}, title = {{{Interplay between metal-free phthalocyanine molecules and Au(110) substrates}}}, doi = {{10.1016/j.susc.2012.03.010}}, volume = {{606}}, year = {{2012}}, } @article{13560, author = {{Hölscher, R. and Sanna, S. and Schmidt, Wolf Gero}}, issn = {{1862-6351}}, journal = {{physica status solidi (c)}}, number = {{6}}, pages = {{1361--1365}}, title = {{{Adsorption of OH and H at the LiNbO3(0001) surface}}}, doi = {{10.1002/pssc.201100534}}, volume = {{9}}, year = {{2012}}, } @article{13539, author = {{Rode, S. and Hölscher, R. and Sanna, S. and Klassen, S. and Kobayashi, K. and Yamada, H. and Schmidt, Wolf Gero and Kühnle, A.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Atomic-resolution imaging of the polar (0001¯) surface of LiNbO3in aqueous solution by frequency modulation atomic force microscopy}}}, doi = {{10.1103/physrevb.86.075468}}, volume = {{86}}, year = {{2012}}, } @article{13534, author = {{Wall, Simone and Krenzer, Boris and Wippermann, Stefan and Sanna, Simone and Klasing, Friedrich and Hanisch-Blicharski, Anja and Kammler, Martin and Schmidt, Wolf Gero and Horn-von Hoegen, Michael}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{18}}, title = {{{Atomistic Picture of Charge Density Wave Formation at Surfaces}}}, doi = {{10.1103/physrevlett.109.186101}}, volume = {{109}}, year = {{2012}}, } @article{13536, author = {{Riefer, Arthur and Sanna, Simone and Gavrilenko, Alexander V. and Schmidt, Wolf Gero}}, issn = {{0885-3010}}, journal = {{IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control}}, number = {{9}}, pages = {{1929--1933}}, title = {{{Linear and nonlinear optical response of LiNbO3 calculated from first principles}}}, doi = {{10.1109/tuffc.2012.2409}}, volume = {{59}}, year = {{2012}}, } @article{13541, author = {{Landmann, M. and Köhler, T. and Köppen, S. and Rauls, E. and Frauenheim, T. and Schmidt, Wolf Gero}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{6}}, title = {{{Fingerprints of order and disorder in the electronic and optical properties of crystalline and amorphous TiO2}}}, doi = {{10.1103/physrevb.86.064201}}, volume = {{86}}, year = {{2012}}, } @article{13531, author = {{Schmidt, Christian and Breuer, Tobias and Wippermann, Stefan and Schmidt, Wolf Gero and Witte, Gregor}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{24098--24106}}, title = {{{Substrate Induced Thermal Decomposition of Perfluoro-Pentacene Thin Films on the Coinage Metals}}}, doi = {{10.1021/jp307316r}}, volume = {{116}}, year = {{2012}}, } @article{13535, author = {{Sanna, S. and Schmidt, Wolf Gero}}, issn = {{0885-3010}}, journal = {{IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control}}, number = {{9}}, pages = {{1925--1928}}, title = {{{Ferroelectric phase transition in LiNbO3: Insights from molecular dynamics}}}, doi = {{10.1109/tuffc.2012.2408}}, volume = {{59}}, year = {{2012}}, } @article{13538, author = {{Riefer, A. and Sanna, S. and Schmidt, Wolf Gero}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{12}}, title = {{{Polarization-dependent methanol adsorption on lithium niobate Z-cut surfaces}}}, doi = {{10.1103/physrevb.86.125410}}, volume = {{86}}, year = {{2012}}, } @article{62927, abstract = {{To model intermolecular excitation transfer between organic chromophores in the framework of Förster theory, the interaction matrix element is needed for all relative orientations and separations of chromophores. Simulations of extended multi-chromophoric systems thus require a fast but reliable approximation scheme to calculate these dipole interactions. By means of a comparative study of the dipole approximation with quantum chemistry, we demonstrate that the usual line-dipole theory, while suitable for short molecules, breaks down for longer molecules with inter-molecular separations similar to or smaller than the length of the interacting chromophores; a limit that is typically found in conjugated polymer thin films. As a remedy, we propose an improved way of distributing the sub-dipole moments within a line which provides results in very good agreement with the quantum chemistry, and is still simple enough to be used in large scale simulations.}}, author = {{Denis, Jean-Christophe and Schumacher, Stefan and Galbraith, Ian}}, issn = {{0021-9606}}, journal = {{The Journal of Chemical Physics}}, number = {{22}}, publisher = {{AIP Publishing}}, title = {{{Quantitative description of interactions between linear organic chromophores}}}, doi = {{10.1063/1.4768244}}, volume = {{137}}, year = {{2012}}, } @article{15869, author = {{Wiebeler, Christian and Tautz, Raphael and Feldmann, Jochen and von Hauff, Elizabeth and Da Como, Enrico and Schumacher, Stefan}}, issn = {{1520-6106}}, journal = {{The Journal of Physical Chemistry B}}, pages = {{4454--4460}}, title = {{{Spectral Signatures of Polarons in Conjugated Co-polymers}}}, doi = {{10.1021/jp3084869}}, year = {{2012}}, } @article{13820, author = {{Schmidt, Wolf Gero and Wippermann, S. and Sanna, S. and Babilon, M. and Vollmers, N. J. and Gerstmann, Uwe}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, number = {{2}}, pages = {{343--359}}, title = {{{In-Si(111)(4 × 1)/(8 × 2) nanowires: Electron transport, entropy, and metal-insulator transition}}}, doi = {{10.1002/pssb.201100457}}, volume = {{249}}, year = {{2012}}, } @article{15872, author = {{Montgomery, Neil A. and Hedley, Gordon J. and Ruseckas, Arvydas and Denis, Jean-Christophe and Schumacher, Stefan and Kanibolotsky, Alexander L. and Skabara, Peter J. and Galbraith, Ian and Turnbull, Graham A. and Samuel, Ifor D. W.}}, issn = {{1463-9076}}, journal = {{Physical Chemistry Chemical Physics}}, title = {{{Dynamics of fluorescence depolarisation in star-shaped oligofluorene-truxene molecules}}}, doi = {{10.1039/c2cp24141b}}, year = {{2012}}, } @article{18542, abstract = {{We present recent advances in numerical implementations of hybrid functionals and the GW approximation within the full-potential linearized augmented-plane-wave (FLAPW) method. The former is an approximation for the exchange–correlation contribution to the total energy functional in density-functional theory, and the latter is an approximation for the electronic self-energy in the framework of many-body perturbation theory. All implementations employ the mixed product basis, which has evolved into a versatile basis for the products of wave functions, describing the incoming and outgoing states of an electron that is scattered by interacting with another electron. It can thus be used for representing the nonlocal potential in hybrid functionals as well as the screened interaction and related quantities in GW calculations. In particular, the six-dimensional space integrals of the Hamiltonian exchange matrix elements (and exchange self-energy) decompose into sums over vector–matrix–vector products, which can be evaluated easily. The correlation part of the GW self-energy, which contains a time or frequency dependence, is calculated on the imaginary frequency axis with a subsequent analytic continuation to the real axis or, alternatively, by a direct frequency convolution of the Green function G and the dynamically screened Coulomb interaction W along a contour integration path that avoids the poles of the Green function. Hybrid-functional and GW calculations are notoriously computationally expensive. We present a number of tricks that reduce the computational cost considerably, including the use of spatial and time-reversal symmetries, modifications of the mixed product basis with the aim to optimize it for the correlation self-energy and another modification that makes the Coulomb matrix sparse, analytic expansions of the interaction potentials around the point of divergence at k=0, and a nested density and density-matrix convergence scheme for hybrid-functional calculations. We show CPU timings for prototype semiconductors and illustrative results for GdN and ZnO. }}, author = {{Friedrich, Christoph and Betzinger, Markus and Schlipf, Martin and Blügel, Stefan and Schindlmayr, Arno}}, issn = {{1361-648X}}, journal = {{Journal of Physics: Condensed Matter}}, number = {{29}}, publisher = {{IOP Publishing}}, title = {{{Hybrid functionals and GW approximation in the FLAPW method}}}, doi = {{10.1088/0953-8984/24/29/293201}}, volume = {{24}}, year = {{2012}}, } @article{4104, abstract = {{We report on the molecular beam epitaxy growth of cubic GaN on 3C–SiC (001) nanostructures. Transmission electron microscopy (TEM) studies show phase-pure cubic GaN crystals with a low defect density on top of the post shaped 3C–SiC nanostructures and GaN grown on their sidewalls, which is dominated by {111} planar defects. The nanostructures, aligned parallel and perpendicular to the [110] directions of the substrate, are located in anti-phase domains of the 3C–SiC/Si (001) substrate. These anti-phase domains strongly influence the optimum growth of GaN layers in these regions. TEM measurements demonstrate a different stacking fault density in the cubic GaN epilayer in these areas.}}, author = {{Kemper, R.M. and Hiller, L. and Stauden, T. and Pezoldt, J. and Duschik, K. and Niendorf, T. and Maier, H.J. and Meertens, D. and Tillmann, K. and As, D.J. and Lindner, Jörg}}, issn = {{0022-0248}}, journal = {{Journal of Crystal Growth}}, location = {{Nara (Japan)}}, pages = {{291--294}}, publisher = {{Elsevier BV}}, title = {{{Growth of cubic GaN on 3C–SiC/Si (001) nanostructures}}}, doi = {{10.1016/j.jcrysgro.2012.10.011}}, volume = {{378}}, year = {{2012}}, } @article{3974, abstract = {{We study the quantum properties and statistics of photons emitted by a quantum-dot biexciton inside a cavity. In the biexciton-exciton cascade, fine-structure splitting between exciton levels degrades polarization-entanglement for the emitted pair of photons. However, here we show that the polarization-entanglement can be preserved in such a system through simultaneous emission of two degenerate photons into cavity modes tuned to half the biexciton energy. Based on detailed theoretical calculations for realistic quantum-dot and cavity parameters, we quantify the degree of achievable entanglement.}}, author = {{Schumacher, Stefan and Förstner, Jens and Zrenner, Artur and Florian, Matthias and Gies, Christopher and Gartner, Paul and Jahnke, Frank}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_qd}}, number = {{5}}, pages = {{5335--5342}}, publisher = {{OSA}}, title = {{{Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting}}}, doi = {{10.1364/oe.20.005335}}, volume = {{20}}, year = {{2012}}, } @article{40405, author = {{Sharapova, Polina and Tikhonova, O V}}, issn = {{1063-7818}}, journal = {{Quantum Electronics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics, Electronic, Optical and Magnetic Materials}}, number = {{3}}, pages = {{199--207}}, publisher = {{IOP Publishing}}, title = {{{Dynamics of ionisation and entanglement in the 'atom + quantum electromagnetic field' system}}}, doi = {{10.1070/qe2012v042n03abeh014805}}, volume = {{42}}, year = {{2012}}, } @inproceedings{3965, abstract = {{We design the geometrical shape of plasmonic nanostructures to achieve field patterns with desired properties. For this, we combine Maxwell simulations and automatic optimization techniques. By allowing variations of the geometrical shape, which can be based on either boxes or arbitrary polygons, we maximize the desired objective.}}, author = {{Hildebrandt, Andre and Reichelt, Matthias and Meier, Torsten and Förstner, Jens}}, keywords = {{tet_topic_optical antenna, tet_topic_plasmonics}}, location = {{Bad Honnef}}, number = {{59}}, publisher = {{AIP AIP Conference Proceedings 1475}}, title = {{{Optimization of the intensity enhancement in plasmonic nanoantennas}}}, doi = {{10.1063/1.4750095}}, year = {{2012}}, }