@article{19194, author = {{Biktagirov, Timur and Schmidt, Wolf Gero and Gerstmann, Uwe}}, issn = {{2643-1564}}, journal = {{Physical Review Research}}, title = {{{Spin decontamination for magnetic dipolar coupling calculations: Application to high-spin molecules and solid-state spin qubits}}}, doi = {{10.1103/physrevresearch.2.022024}}, year = {{2020}}, } @article{19193, author = {{Niederhausen, Jens and MacQueen, Rowan W. and Lips, Klaus and Aldahhak, Hazem and Schmidt, Wolf Gero and Gerstmann, Uwe}}, issn = {{0743-7463}}, journal = {{Langmuir}}, pages = {{9099--9113}}, title = {{{Tetracene Ultrathin Film Growth on Hydrogen-Passivated Silicon}}}, doi = {{10.1021/acs.langmuir.0c01154}}, year = {{2020}}, } @article{19654, author = {{Krenz, Marvin and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{2470-1343}}, journal = {{ACS Omega}}, pages = {{24057--24063}}, title = {{{Photochemical Ring Opening of Oxirane Modeled by Constrained Density Functional Theory}}}, doi = {{10.1021/acsomega.0c03483}}, year = {{2020}}, } @article{17070, abstract = {{

EPR spectroscopy reveals the universality class and dynamic effects of the [NH4][Zn(HCOO)3] hybrid formate framework.

}}, author = {{Navickas, Marius and Giriūnas, Laisvydas and Kalendra, Vidmantas and Biktagirov, Timur and Gerstmann, Uwe and Schmidt, Wolf Gero and Mączka, Mirosław and Pöppl, Andreas and Banys, Jūras and Šimėnas, Mantas}}, issn = {{1463-9076}}, journal = {{Physical Chemistry Chemical Physics}}, pages = {{8513--8521}}, title = {{{Electron paramagnetic resonance study of ferroelectric phase transition and dynamic effects in a Mn2+ doped [NH4][Zn(HCOO)3] hybrid formate framework}}}, doi = {{10.1039/d0cp01612h}}, volume = {{22}}, year = {{2020}}, } @article{19189, abstract = {{Density-functional theory calculations of (TiO2)n clusters (n = 1–5) in the gas phase and adsorbed on pristine graphene as well as graphene quantum dots are presented. The cluster adsorption is found to be dominated by van der Waals forces. The electronic structure and in particular the excitation energies of the bare clusters and the TiO2/graphene composites are found to vary largely in dependence on the size of the respective constituents. This holds in particular for the energy and the spatial localization of the highest occupied and lowest unoccupied molecular orbitals. In addition to a substantial gap narrowing, a pronounced separation of photoexcited electrons and holes is predicted in some instances. This is expected to prolong the lifetime of photoexcited carriers. Altogether, TiO2/graphene composites are predicted to be promising photocatalysts with improved electronic and photocatalytic properties compared to bulk TiO2.}}, author = {{Badalov, Sabuhi and Wilhelm, René and Schmidt, Wolf Gero}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, pages = {{1921--1930}}, publisher = {{Willey}}, title = {{{Photocatalytic properties of graphene‐supported titania clusters from density‐functional theory}}}, doi = {{10.1002/jcc.26363}}, year = {{2020}}, } @article{20682, author = {{Bocchini, Adriana and Eigner, Christof and Silberhorn, Christine and Schmidt, Wolf Gero and Gerstmann, Uwe}}, journal = {{Phys. Rev. Materials}}, pages = {{124402}}, publisher = {{American Physical Society}}, title = {{{Understanding gray track formation in KTP: Ti^3+ centers studied from first principles}}}, doi = {{10.1103/PhysRevMaterials.4.124402}}, volume = {{4}}, year = {{2020}}, } @article{29744, abstract = {{

A hole transfer from an excited Ru unit towards graphene oxide significantly improved the photocatalytic activity of the complexes.

}}, author = {{Rosenthal, Marta and Lindner, Jörg and Gerstmann, Uwe and Meier, Armin and Schmidt, Wolf Gero and Wilhelm, René}}, issn = {{2046-2069}}, journal = {{RSC Advances}}, keywords = {{General Chemical Engineering, General Chemistry}}, number = {{70}}, pages = {{42930--42937}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{A photoredox catalysed Heck reaction via hole transfer from a Ru(ii)-bis(terpyridine) complex to graphene oxide}}}, doi = {{10.1039/d0ra08749a}}, volume = {{10}}, year = {{2020}}, } @article{17068, author = {{Braun, Christian and Neufeld, Sergej and Gerstmann, Uwe and Sanna, S. and Plaickner, J. and Speiser, E. and Esser, N. and Schmidt, Wolf Gero}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{14}}, title = {{{Vibration-Driven Self-Doping of Dangling-Bond Wires on Si(553)-Au Surfaces}}}, doi = {{10.1103/physrevlett.124.146802}}, volume = {{124}}, year = {{2020}}, } @article{10014, abstract = {{The cubic, tetragonal, and orthorhombic phase of potassium niobate (KNbO3) are studied based on density-functional theory. Starting from the relaxed atomic geometries, we analyze the influence of self-energy corrections on the electronic band structure within the GW approximation. We find that quasiparticle shifts widen the direct (indirect) band gap by 1.21 (1.44), 1.58 (1.55), and 1.67 (1.64) eV for the cubic, tetragonal, and orthorhombic phase, respectively. By solving the Bethe-Salpeter equation, we obtain the linear dielectric function with excitonic and local-field effects, which turn out to be essential for good agreement with experimental data. From our results, we extract an exciton binding energy of 0.6, 0.5, and 0.5 eV for the cubic, tetragonal, and orthorhombic phase, respectively. Furthermore, we investigate the nonlinear second-harmonic generation (SHG) both theoretically and experimentally. The frequency-dependent second-order polarization tensor of orthorhombic KNbO3 is measured for incoming photon energies between 1.2 and 1.6 eV. In addition, calculations within the independent-(quasi)particle approximation are performed for the tetragonal and orthorhombic phase. The novel experimental data are in excellent agreement with the quasiparticle calculations and resolve persistent discrepancies between earlier experimental measurements and ab initio results reported in the literature.}}, author = {{Schmidt, Falko and Riefer, Arthur and Schmidt, Wolf Gero and Schindlmayr, Arno and Imlau, Mirco and Dobener, Florian and Mengel, Nils and Chatterjee, Sangam and Sanna, Simone}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{5}}, publisher = {{American Physical Society}}, title = {{{Quasiparticle and excitonic effects in the optical response of KNbO3}}}, doi = {{10.1103/PhysRevMaterials.3.054401}}, volume = {{3}}, year = {{2019}}, } @article{29746, author = {{Nicholson, C. W. and Puppin, M. and Lücke, A. and Gerstmann, Uwe and Krenz, Marvin and Schmidt, Wolf Gero and Rettig, L. and Ernstorfer, R. and Wolf, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{15}}, publisher = {{American Physical Society (APS)}}, title = {{{Excited-state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV-based time- and angle-resolved photoemission spectroscopy}}}, doi = {{10.1103/physrevb.99.155107}}, volume = {{99}}, year = {{2019}}, } @article{10015, author = {{Dues, Christof and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{2470-1343}}, journal = {{ACS Omega}}, pages = {{3850--3859}}, title = {{{Water Splitting Reaction at Polar Lithium Niobate Surfaces}}}, doi = {{10.1021/acsomega.8b03271}}, year = {{2019}}, } @article{13365, abstract = {{The KTiOPO4 (KTP) band structure and dielectric function are calculated on various levels of theory starting from density-functional calculations. Within the independent-particle approximation an electronic transport gap of 2.97 eV is obtained that widens to about 5.23 eV when quasiparticle effects are included using the GW approximation. The optical response is shown to be strongly anisotropic due to (i) the slight asymmetry of the TiO6 octahedra in the (001) plane and (ii) their anisotropic distribution along the [001] and [100] directions. In addition, excitonic effects are very important: The solution of the Bethe–Salpeter equation indicates exciton binding energies of the order of 1.5 eV. Calculations that include both quasiparticle and excitonic effects are in good agreement with the measured reflectivity.}}, author = {{Neufeld, Sergej and Bocchini, Adriana and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, pages = {{045003}}, publisher = {{IOP Publishing}}, title = {{{Potassium titanyl phosphate (KTP) quasiparticle energies and optical response}}}, doi = {{10.1088/2515-7639/ab29ba}}, volume = {{2}}, year = {{2019}}, } @article{13429, author = {{Bocchini, Adriana and Neufeld, Sergej and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{0953-8984}}, journal = {{Journal of Physics: Condensed Matter}}, pages = {{385401}}, title = {{{Oxygen and potassium vacancies in KTP calculated from first principles}}}, doi = {{10.1088/1361-648x/ab295c}}, volume = {{31}}, year = {{2019}}, } @article{10013, abstract = {{Ultrafast nonequilibrium dynamics offer a route to study the microscopic interactions that govern macroscopic behavior. In particular, photoinduced phase transitions (PIPTs) in solids provide a test case for how forces, and the resulting atomic motion along a reaction coordinate, originate from a nonequilibrium population of excited electronic states. Using femtosecond photoemission, we obtain access to the transient electronic structure during an ultrafast PIPT in a model system: indium nanowires on a silicon(111) surface. We uncover a detailed reaction pathway, allowing a direct comparison with the dynamics predicted by ab initio simulations. This further reveals the crucial role played by localized photoholes in shaping the potential energy landscape and enables a combined momentum- and real-space description of PIPTs, including the ultrafast formation of chemical bonds.}}, author = {{Nicholson, C. W. and Lücke, A. and Schmidt, Wolf Gero and Puppin, M. and Rettig, L. and Ernstorfer, R. and Wolf, M.}}, issn = {{0036-8075}}, journal = {{Science}}, pages = {{821--825}}, title = {{{Beyond the molecular movie: Dynamics of bands and bonds during a photoinduced phase transition}}}, doi = {{10.1126/science.aar4183}}, year = {{2018}}, } @article{10016, author = {{Paszkiewicz, Mateusz and Biktagirov, Timur and Aldahhak, Hazem and Allegretti, Francesco and Rauls, Eva and Schöfberger, Wolfgang and Schmidt, Wolf Gero and Barth, Johannes V. and Gerstmann, Uwe and Klappenberger, Florian}}, issn = {{1948-7185}}, journal = {{The Journal of Physical Chemistry Letters}}, pages = {{6412--6420}}, title = {{{Unraveling the Oxidation and Spin State of Mn–Corrole through X-ray Spectroscopy and Quantum Chemical Analysis}}}, doi = {{10.1021/acs.jpclett.8b02525}}, year = {{2018}}, } @article{10019, author = {{Aldahhak, Hazem and Paszkiewicz, M. and Rauls, E. and Allegretti, F. and Tebi, S. and Papageorgiou, A. C. and Zhang, Y.-Q. and Zhang, L. and Lin, T. and Paintner, T. and Koch, R. and Schmidt, Wolf Gero and Barth, J. V. and Schöfberger, W. and Müllegger, S. and Klappenberger, F. and Gerstmann, Uwe}}, issn = {{0947-6539}}, journal = {{Chemistry - A European Journal}}, pages = {{6787--6797}}, title = {{{Identifying On-Surface Site-Selective Chemical Conversions by Theory-Aided NEXAFS Spectroscopy: The Case of Free-Base Corroles on Ag(111)}}}, doi = {{10.1002/chem.201705921}}, year = {{2018}}, } @article{4769, abstract = {{In recent years, Raman spectroscopy has been used to visualize and analyze ferroelectric domain structures. The technique makes use of the fact that the intensity or frequency of certain phonons is strongly influenced by the presence of domain walls. Although the method is used frequently, the underlying mechanism responsible for the changes in the spectra is not fully understood. This inhibits deeper analysis of domain structures based on this method. Two different models have been proposed. However, neither model completely explains all observations. In this work, we have systematically investigated domain walls in different scattering geometries with Raman spectroscopy in the common ferroelectric materials used in integrated optics, i.e., KTiOPO4, LiNbO3, and LiTaO3. Based on the two models, we can demonstrate that the observed contrast for domain walls is in fact based on two different effects. We can identify on the one hand microscopic changes at the domain wall, e.g., strain and electric fields, and on the other hand a macroscopic change of selection rules at the domain wall. While the macroscopic relaxation of selection rules can be explained by the directional dispersion of the phonons in agreement with previous propositions, the microscopic changes can be explained qualitatively in terms of a simplified atomistic model.}}, author = {{Rüsing, Michael and Neufeld, Sergej and Brockmeier, Julian and Eigner, Christof and Mackwitz, P. and Spychala, K. and Silberhorn, Christine and Schmidt, Wolf Gero and Berth, Gerhard and Zrenner, Artur and Sanna, S.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{10}}, publisher = {{American Physical Society (APS)}}, title = {{{Imaging of 180∘ ferroelectric domain walls in uniaxial ferroelectrics by confocal Raman spectroscopy: Unraveling the contrast mechanism}}}, doi = {{10.1103/physrevmaterials.2.103801}}, volume = {{2}}, year = {{2018}}, } @article{10018, author = {{Schmidt, Claudia and Bühler, J. and Heinrich, A.-C. and Allerbeck, J. and Podzimski, R. and Berghoff, Daniel and Meier, Torsten and Schmidt, Wolf Gero and Reichl, C. and Wegscheider, W. and Brida, D. and Leitenstorfer, A.}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, title = {{{Signatures of transient Wannier-Stark localization in bulk gallium arsenide}}}, doi = {{10.1038/s41467-018-05229-x}}, volume = {{9}}, year = {{2018}}, } @article{13405, author = {{Müller, Patrick and Karhan, Kristof and Krack, Matthias and Gerstmann, Uwe and Schmidt, Wolf Gero and Bauer, Matthias and Kühne, Thomas D.}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, pages = {{712--716}}, title = {{{Impact of finite-temperature and condensed-phase effects on theoretical X-ray absorption spectra of transition metal complexes}}}, doi = {{10.1002/jcc.25641}}, year = {{2018}}, } @article{13406, author = {{Mamiyev, Z. and Lichtenstein, T. and Tegenkamp, C. and Braun, Christian and Schmidt, Wolf Gero and Sanna, S. and Pfnür, H.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{6}}, title = {{{Plasmon spectroscopy: Robust metallicity of Au wires on Si(557) upon oxidation}}}, doi = {{10.1103/physrevmaterials.2.066002}}, volume = {{2}}, year = {{2018}}, }