@article{13915, abstract = {{The dynamics of a pair of harmonic oscillators represented by three-dimensional fields coupled with a repulsive cubic nonlinearity is investigated through direct simulations of the respective field equations and with the help of the finite-mode Galerkin approximation (GA), which represents the two interacting fields by a superposition of 3+3 harmonic-oscillator p-wave eigenfunctions with orbital and magnetic quantum numbers l=1 and m=1, 0, −1. The system can be implemented in binary Bose-Einstein condensates, demonstrating the potential of the atomic condensates to emulate various complex modes predicted by classical field theories. First, the GA very accurately predicts a broadly degenerate set of the system's ground states in the p-wave manifold, in the form of complexes built of a dipole coaxial with another dipole or vortex, as well as complexes built of mutually orthogonal dipoles. Next, pairs of noncoaxial vortices and/or dipoles, including pairs of mutually perpendicular vortices, develop remarkably stable dynamical regimes, which feature periodic exchange of the angular momentum and periodic switching between dipoles and vortices. For a moderately strong nonlinearity, simulations of the coupled-field equations agree very well with results produced by the GA, demonstrating that the dynamics is accurately spanned by the set of six modes limited to l=1.}}, author = {{Driben, R. and Konotop, V. V. and Malomed, B. A. and Meier, Torsten}}, issn = {{2470-0045}}, journal = {{Physical Review E}}, number = {{1}}, title = {{{Dynamics of dipoles and vortices in nonlinearly coupled three-dimensional field oscillators}}}, doi = {{10.1103/physreve.94.012207}}, volume = {{94}}, year = {{2016}}, } @inproceedings{13918, author = {{Podzimski, Reinold and Duc, Huynh Thanh and Priyadarshi, Shekhar and Schmidt, Christian and Bieler, Mark and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XX}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, publisher = {{SPIE}}, title = {{{Photocurrents in semiconductors and semiconductor quantum wells analyzed by k.p-based Bloch equations}}}, doi = {{10.1117/12.2208572}}, volume = {{9746}}, year = {{2016}}, } @article{22942, abstract = {{A microscopic approach that is based on the multisubband semiconductor Bloch equations formulated in the basis of a 14-band k⋅p model is employed to compute the temporal dynamics of photocurrents in GaAs quantum wells following excitation with femtosecond laser pulses. This approach provides a transparent description of the interband, intersubband, and intraband excitations, fully includes all resonant as well as off-resonant excitations, and treats the light-matter interaction nonperturbatively. For linearly polarized excitations, the photocurrents contain contributions from shift and rectification currents. We numerically compute and analyze these currents generated by excitation with femtosecond laser pulses for [110]- and [111]-oriented GaAs quantum wells. It is shown that the often employed perturbative χ(2) approach breaks down for peak fields larger than about 10 kV/cm, and that nonperturbative effects lead to a reduction of the peak values of the shift and rectification currents and to temporal oscillations that originate from Rabi flopping. In particular, we find a complex oscillatory photon energy dependence of the magnitudes of the shift and rectification currents. Our simulations demonstrate that this dependence is the result of mixing between the heavy- and light-hole valence bands. This is a surprising finding since the band mixing has an even larger influence on the strength of the photocurrents than the absorption coefficient. For [110]-oriented GaAs quantum wells, the calculated photon energy dependence is compared to experimental results, and good agreement is obtained. This validates our theoretical approach.}}, author = {{Duc, Huynh Thanh and Podzimski, Reinold and Priyadarshi, Shekhar and Bieler, Mark and Meier, Torsten}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{8}}, publisher = {{American Physical Society}}, title = {{{Ultrafast shift and rectification photocurrents in GaAs quantum wells: Excitation intensity dependence and the importance of band mixing}}}, doi = {{10.1103/physrevb.94.085305}}, volume = {{94}}, year = {{2016}}, } @article{13916, abstract = {{Nonlinearity is the driving force for numerous important effects in nature typically showing transitions between different regimes, regular, chaotic or catastrophic behavior. Localized nonlinear modes have been the focus of intense research in areas such as fluid and gas dynamics, photonics, atomic and solid state physics etc. Due to the richness of the behavior of nonlinear systems and due to the severe numerical demands of accurate three-dimensional (3D) numerical simulations presently only little knowledge is available on the dynamics of complex nonlinear modes in 3D. Here, we investigate the dynamics of 3D non-coaxial matter wave vortices that are trapped in a parabolic potential and interact via a repulsive nonlinearity. Our numerical simulations demonstrate the existence of an unexpected and fascinating nonlinear regime that starts immediately when the nonlinearity is switched-on and is characterized by a smooth dynamics representing torque-free precession with nutations. The reported motion is proven to be robust regarding various effects such as the number of particles, dissipation and trap deformations and thus should be observable in suitably designed experiments. Since our theoretical approach, i.e., coupled nonlinear Schrödinger equations, is quite generic, we expect that the obtained novel dynamical behavior should also exist in other nonlinear systems.}}, author = {{Driben, R. and Konotop, V. V. and Meier, Torsten}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, title = {{{Precession and nutation dynamics of nonlinearly coupled non-coaxial three-dimensional matter wave vortices}}}, doi = {{10.1038/srep22758}}, volume = {{6}}, year = {{2016}}, } @article{13920, abstract = {{We investigate the transient optical response in high-quality Cd0.88Zn0.12Te crystals in the regime of slow light propagation on the lower exciton-polariton branch. Femtosecond photoexcitation leads to very substantial transmission changes in a ∼10-meV broad spectral range within the transparency window of the unexcited semiconductor. These nonlinear optical signatures decay on picosecond time scales governed by carrier thermalization and recombination. The temporal and spectral dependence indicate the dynamical optical response as arising from excitation-induced dephasing and perturbed free induction decay. Model simulations for the optical response taking into account the actual exciton-polariton dispersion and excitation-induced dephasing of a nonlinearly driven two-level system support this interpretation.}}, author = {{Lohrenz, J. and Melzer, S. and Ruppert, C. and Akimov, I. A. and Mariette, H. and Reichelt, Matthias and Trautmann, Alexander and Meier, Torsten and Betz, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Ultrafast dynamical response of the lower exciton-polariton branch in CdZnTe}}}, doi = {{10.1103/physrevb.93.075201}}, volume = {{93}}, year = {{2016}}, } @article{1454, author = {{Grynko, Yevgen and Zentgraf, Thomas and Meier, Torsten and Förstner, Jens}}, issn = {{0946-2171}}, journal = {{Applied Physics B}}, keywords = {{tet_topic_meta, tet_topic_shg}}, number = {{9}}, pages = {{242}}, publisher = {{Springer Nature}}, title = {{{Simulations of high harmonic generation from plasmonic nanoparticles in the terahertz region}}}, doi = {{10.1007/s00340-016-6510-0}}, volume = {{122}}, year = {{2016}}, } @article{10024, abstract = {{The influence of electronic many-body interactions, spin-orbit coupling, and thermal lattice vibrations on the electronic structure of lithium niobate is calculated from first principles. Self-energy calculations in the GW approximation show that the inclusion of self-consistency in the Green function G and the screened Coulomb potential W opens the band gap far stronger than found in previous G0W0 calculations but slightly overestimates its actual value due to the neglect of excitonic effects in W. A realistic frozen-lattice band gap of about 5.9 eV is obtained by combining hybrid density functional theory with the QSGW0 scheme. The renormalization of the band gap due to electron-phonon coupling, derived here using molecular dynamics as well as density functional perturbation theory, reduces this value by about 0.5 eV at room temperature. Spin-orbit coupling does not noticeably modify the fundamental gap but gives rise to a Rashba-like spin texture in the conduction band.}}, author = {{Riefer, Arthur and Friedrich, Michael and Sanna, Simone and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2469-9969}}, journal = {{Physical Review B}}, number = {{7}}, publisher = {{American Physical Society}}, title = {{{LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects}}}, doi = {{10.1103/PhysRevB.93.075205}}, volume = {{93}}, year = {{2016}}, } @article{10025, abstract = {{The phonon dispersions of the ferro‐ and paraelectric phase of LiTaO3 are calculated within density‐functional perturbation theory. The longitudinal optical phonon modes are theoretically derived and compared with available experimental data. Our results confirm the recent phonon assignment proposed by Margueron et al. [J. Appl. Phys. 111, 104105 (2012)] on the basis of spectroscopical studies. A comparison with the phonon band structure of the related material LiNbO3 shows minor differences that can be traced to the atomic‐mass difference between Ta and Nb. The presence of phonons with imaginary frequencies for the paraelectric phase suggests that it does not correspond to a minimum energy structure, and is compatible with an order‐disorder type phase transition.}}, author = {{Friedrich, Michael and Schindlmayr, Arno and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{1521-3951}}, journal = {{Physica Status Solidi B}}, number = {{4}}, pages = {{683--689}}, publisher = {{Wiley-VCH}}, title = {{{LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles}}}, doi = {{10.1002/pssb.201552576}}, volume = {{253}}, year = {{2016}}, } @article{13492, author = {{Tebi, Stefano and Aldahhak, Hazem and Serrano, Giulia and Schöfberger, Wolfgang and Rauls, Eva and Schmidt, Wolf Gero and Koch, Reinhold and Müllegger, Stefan}}, issn = {{0957-4484}}, journal = {{Nanotechnology}}, title = {{{Manipulation resolves non-trivial structure of corrole monolayer on Ag(111)}}}, doi = {{10.1088/0957-4484/27/2/025704}}, volume = {{27}}, year = {{2016}}, } @article{13491, author = {{Schöfberger, Wolfgang and Faschinger, Felix and Chattopadhyay, Samir and Bhakta, Snehadri and Mondal, Biswajit and Elemans, Johannes A. A. W. and Müllegger, Stefan and Tebi, Stefano and Koch, Reinhold and Klappenberger, Florian and Paszkiewicz, Mateusz and Barth, Johannes V. and Rauls, Eva and Aldahhak, Hazem and Schmidt, Wolf Gero and Dey, Abhishek}}, issn = {{1433-7851}}, journal = {{Angewandte Chemie International Edition}}, pages = {{2350--2355}}, title = {{{A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water}}}, doi = {{10.1002/anie.201508404}}, year = {{2016}}, } @article{13476, author = {{Vollmers, Nora Jenny and Müller, Patrick and Hoffmann, Alexander and Herres-Pawlis, Sonja and Rohrmüller, Martin and Schmidt, Wolf Gero and Gerstmann, Uwe and Bauer, Matthias}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, pages = {{11694--11706}}, title = {{{Experimental and Theoretical High-Energy-Resolution X-ray Absorption Spectroscopy: Implications for the Investigation of the Entatic State}}}, doi = {{10.1021/acs.inorgchem.6b01704}}, volume = {{55}}, year = {{2016}}, } @article{13477, author = {{Witte, Matthias and Grimm-Lebsanft, Benjamin and Goos, Arne and Binder, Stephan and Rübhausen, Michael and Bernard, Martin and Neuba, Adam and Gorelsky, Serge and Gerstmann, Uwe and Henkel, Gerald and Schmidt, Wolf Gero and Herres-Pawlis, Sonja}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, number = {{23-24}}, pages = {{2181--2192}}, title = {{{Optical response of the Cu2S2diamond core in Cu2II(NGuaS)2Cl2}}}, doi = {{10.1002/jcc.24439}}, volume = {{37}}, year = {{2016}}, } @article{13479, author = {{Lücke, Andreas and Ortmann, Frank and Panhans, Michel and Sanna, Simone and Rauls, Eva and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{1520-6106}}, journal = {{The Journal of Physical Chemistry B}}, pages = {{5572--5580}}, title = {{{Temperature-Dependent Hole Mobility and Its Limit in Crystal-Phase P3HT Calculated from First Principles}}}, doi = {{10.1021/acs.jpcb.6b03598}}, volume = {{120}}, year = {{2016}}, } @article{13480, author = {{Paulheim, A. and Marquardt, C. and Aldahhak, Hazem and Rauls, E. and Schmidt, Wolf Gero and Sokolowski, M.}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{11926--11937}}, title = {{{Inhomogeneous and Homogeneous Line Broadening of Optical Spectra of PTCDA Molecules Adsorbed at Step Edges of Alkali Halide Surfaces}}}, doi = {{10.1021/acs.jpcc.6b01956}}, volume = {{10}}, year = {{2016}}, } @article{13485, author = {{Sanna, S. and Dues, C. and Schmidt, Wolf Gero and Timmer, F. and Wollschläger, J. and Franz, M. and Appelfeller, S. and Dähne, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{19}}, title = {{{Rare-earth silicide thin films on the Si(111) surface}}}, doi = {{10.1103/physrevb.93.195407}}, volume = {{93}}, year = {{2016}}, } @article{13487, author = {{Witte, M. and Gerstmann, Uwe and Neuba, Adam and Henkel, G. and Schmidt, Wolf Gero}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, pages = {{1005--1018}}, title = {{{Density functional theory of the CuA-like Cu2S2 diamond core in Cu 2II(NGuaS)2Cl2}}}, doi = {{10.1002/jcc.24289}}, volume = {{37}}, year = {{2016}}, } @article{13481, author = {{Jeckelmann, Eric and Sanna, Simone and Schmidt, Wolf Gero and Speiser, Eugen and Esser, Norbert}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{24}}, title = {{{Grand canonical Peierls transition in In/Si(111)}}}, doi = {{10.1103/physrevb.93.241407}}, volume = {{93}}, year = {{2016}}, } @article{13478, author = {{Speiser, E. and Esser, N. and Wippermann, S. and Schmidt, Wolf Gero}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Surface vibrational Raman modes of In:Si(111)(4×1)and(8×2)nanowires}}}, doi = {{10.1103/physrevb.94.075417}}, volume = {{94}}, year = {{2016}}, } @article{13488, author = {{Miccoli, I. and Edler, F. and Pfnür, H. and Appelfeller, S. and Dähne, M. and Holtgrewe, K. and Sanna, S. and Schmidt, Wolf Gero and Tegenkamp, C.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, title = {{{Atomic size effects studied by transport in single silicide nanowires}}}, doi = {{10.1103/physrevb.93.125412}}, year = {{2016}}, } @article{13458, author = {{Liebhaber, M. and Halbig, B. and Bass, U. and Geurts, J. and Neufeld, Sergej and Sanna, S. and Schmidt, Wolf Gero and Speiser, E. and Räthel, J. and Chandola, S. and Esser, N.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{23}}, title = {{{Vibration eigenmodes of the Au-(5×2)/Si(111) surface studied by Raman spectroscopy and first-principles calculations}}}, doi = {{10.1103/physrevb.94.235304}}, volume = {{94}}, year = {{2016}}, }