K. Schwarz

Vienna University of Technology, Wien, Vienna, Austria

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Publications (178)342.85 Total impact

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    ABSTRACT: Cited By (since 1996): 7, Export Date: 28 May 2012, Source: Scopus, Art. No.: 172401
    Physical Review B 04/2013; 72(17). · 3.74 Impact Factor
  • P.mohn · K.schwarz
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    ABSTRACT: Based on the spin-density functional theory we discuss the essential mechanism of spin-split itinerant electrons which cause the formation of spin-magnetic moments in a solid. The success and the difficulties of the Stoner model of itinerant magnetism is shown for hcp Co. The FSM (fixed spin moment) method allows us to compute the total energy as a function of volume and magnetic moment, E(M, V). These energy surfaces contain the crucial information about magneto-volume instabilities and related phenomena. At finite temperatures collective phenomena such as spin fluctuations are important which can be treated with a Landau—Ginzburg formalism. Results are given for the finite temperature properties of the strongly enhanced Pauli paramagnet fcc Pd and the metamagnetic system YCo2.
    International Journal of Modern Physics B 01/2012; 07(01n03). DOI:10.1142/S0217979293001219 · 0.94 Impact Factor
  • V.l.sliwko · P.blaha · P.mohn · K.schwarz
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    ABSTRACT: We have performed Augmented Spherical Wave (ASW) calculations on bcc Mn and confirmed previous results by Moruzzi and Marcus who reported a ferrimagnetic phase. Independent computations employing the full-potential linearized-augmented-plane-wave (LAPW) method led to similar results. Our ASW results yield the total energy and the magnetic moments as a function of volume assuming different (ferro-, ferri-, antiferro-and non-magnetic) bcc related structures with type I, II, and III spin alignments. We relate the relative stability of various phases to band gaps that open at the Fermi energy for certain volumes. The LAPW symmetry-decomposed partial charges allow to analyze the binding mechanism.
    International Journal of Modern Physics B 01/2012; 07(01n03). DOI:10.1142/S0217979293001293 · 0.94 Impact Factor
  • E.hoffmann · H.herper · P.entel · P.mohn · K.schwarz
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    ABSTRACT: Fixed-spin-moment band-structure calculations of ordered fcc Fe3Ni reveal Fermisurface nesting, which can give rise to a Kohn-like anomaly. This nesting behaviour is very similar to what has recently been seen in nonmagnetic NixAl1–x.1 Using the method of Varma and Weber2 we discuss the renormalized phonon spectrum of Fe3Ni and investigate how the phonon softening and the martensitic transformation depend on the Fermi-surface nesting.
    International Journal of Modern Physics B 01/2012; 07(01n03). DOI:10.1142/S0217979293001426 · 0.94 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 30(34). DOI:10.1002/chin.199934002
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 29(33). DOI:10.1002/chin.199833019
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    ABSTRACT: The stability of SrBi2Ta2O9 has been studied by means of ab-initio calculations. The main instability of the tetragonal configuration concerns a non-polar mode at the Brillouin zone border. It can be related through Brillouin zone folding to the well-known soft rigid-unit mode R25 in perovskites. This implies a complex scenario for the whole Aurivillius family with two competing order parameters, which can result in a sequence of two continuous phase transitions or a single discontinuous one. A third hard-mode is shown to play an essential role in the stabilization of the ferroelectric phase.
    Integrated Ferroelectrics 08/2010; 2004(Vol. 62):183-188. DOI:10.1080/10584580490457244 · 0.36 Impact Factor
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    ABSTRACT: X-ray, synchrotron, and neutron powder diffraction techniques were combined to investigate the evolution of crystal structure and physical properties of La2-xSrxCoIrO6 with temperature and composition x . The following sequence of first- and second-order phase transitions is observed in this system, induced by increasing Sr content and temperature: P21/nP21/n+I2/mI2/mI4/mFm3¯m . The low-temperature magnetic structures are characterized by the propagation vector k=(0,0,0) for x=0 , k=(1/2,0,1/2) for x=1 , and k=(0,1/2,1/2) or k=(1/2,0,1/2) for 1.5 and 2. Different noncollinear magnetic structures are concluded from the combination of magnetization measurements and neutron powder diffraction. Resistivity measurements reveal that the whole series behaves like nonmetals with electronic transport described by a combination of thermal activation and variable range hopping. Band gaps determined by electronic structure calculations agree very well with the experimental data for x=0 and 1, and the calculated occupation of the d bands of Co and Ir are in good agreement with a transition IS/HS-Co2+/LS-Ir4+-->HS-Co3+/LS-Ir5+ with increasing Sr content.
    Physical review. B, Condensed matter 07/2010; 82(2). DOI:10.1103/PhysRevB.82.024403 · 3.66 Impact Factor
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    ABSTRACT: The temperature dependence of the optical and magnetic properties of CuO were examined by means of hybrid density functional theory calculations. Our work shows that the spin exchange interactions in CuO are neither fully one-dimensional nor fully three-dimensional. The large temperature dependence of the optical band gap and the 63Cu nuclear quadrupole resonance frequency of CuO originate from the combined effect of a strong coupling between the spin order and the electronic structure and the progressive appearance of short-range order with temperature.
    Journal of Physics Condensed Matter 02/2010; 22(4):045502. DOI:10.1088/0953-8984/22/4/045502 · 2.35 Impact Factor
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    P. Blaha · H. Hofstätter · O. Koch · R. Laskowski · K. Schwarz
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    ABSTRACT: Due to the increased computer power and advanced algorithms, quantum mechanical calculations based on Density Functional Theory are more and more widely used to solve real materials science problems. In this context large nonlinear generalized eigenvalue problems must be solved repeatedly to calculate the electronic ground state of a solid or molecule. Due to the nonlinear nature of this problem, an iterative solution of the eigenvalue problem can be more efficient provided it does not disturb the convergence of the self-consistent-field problem. The blocked Davidson method is one of the widely used and efficient schemes for that purpose, but its performance depends critically on the preconditioning, i.e. the procedure to improve the search space for an accurate solution. For more diagonally dominated problems, which appear typically for plane wave based pseudopotential calculations, the inverse of the diagonal of (H − ES) is used. However, for the more efficient “augmented plane wave + local-orbitals” basis set this preconditioning is not sufficient due to large off-diagonal terms caused by the local orbitals. We propose a new preconditioner based on the inverse of (H − λS) and demonstrate its efficiency for real applications using both, a sequential and a parallel implementation of this algorithm into our WIEN2k code.
    Journal of Computational Physics 01/2010; 229(2-229):453-460. DOI:10.1016/j.jcp.2009.09.036 · 2.43 Impact Factor
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    R Laskowski · Th Gallauner · P Blaha · K Schwarz
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    ABSTRACT: The electronic structure and the corresponding B K and N K near-edge x-ray fine structure (NEXAFS) spectra of epitaxially grown h-BN on Ni(111), Pt(111), and Rh(111) surfaces are investigated by density functional theory. The calculations are carried out using the WIEN2k program package applying the augmented-plane-wave+local orbitals (APW+lo) method. The NEXAFS spectra are simulated using a 3 × 3 × 1 super cell and considering the final state rule by means of a (partial) core hole for the corresponding atom. The influence of a full or partial core hole is shown for the h-BN/Ni(111) system, for which the best agreement with the experimental spectra is found when half a core hole is assumed. All characteristic features of the experimental spectra are well reproduced by theory, including the angular dependences. The bonding effects are investigated by comparing the spectra of bulk h-BN with those of the h-BN/Ni(111) system. An analysis of both the density of states and charge densities reveals strong N-p(z)-Ni-d(z(2)) bonding/antibonding interactions. In the case of Pt(111) and Rh(111) surfaces, we discuss the effects of the nanomesh structures in terms of simple 1 × 1 commensurate models.
    Journal of Physics Condensed Matter 03/2009; 21(10):104210. DOI:10.1088/0953-8984/21/10/104210 · 2.35 Impact Factor
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    ABSTRACT: The Aurivillius compound Bi4Ti3O12 exhibits a single phase transition from a tetragonal high-temperature phase to a ferroelectric state. By means of first-principles calculations guided by a complete symmetry analysis of the experimental distortion, we confirm B1a1 as the (monoclinic) symmetry of the room-temperature phase but show that the transition involves a complex interplay of six different normal modes belonging to four different irreducible representations. Three of them are necessary for the observed symmetry break. We do not find any feature in the energy landscape that would force the simultaneous condensation of these three order parameters and cause such an avalanche transition, so we suggest that further experimental work might be able to detect intermediate phases. On the other hand, the necessary condensation of pairs of normal modes of the same symmetry already puts Bi4Ti3O12 outside the standard soft-mode paradigm and has important structural implications. In particular, the approximate rigidity of the BiO6 octahedra is due to anharmonic couplings of these modes. In addition, a comparison of the energy calculations and the behavior of the bond-valence global instability index is presented.
    Physical Review B 05/2008; 77(18). DOI:10.1103/PhysRevB.77.184104 · 3.74 Impact Factor
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    ABSTRACT: The replacement of SiO2 by so-called high-κ oxides is one of the major challenges for the semiconductor industry to date. Based on electronic structure calculations and ab initio molecular dynamics simulations, we are able to provide a consistent picture of the growth process of a class of epitaxial oxides around SrO and SrTiO3. To the best of our knowledge this is the only theoretical study which considers the whole growth process starting from the clean Si substrate. Knowledge of the initial growth steps such as metal adsorption on the Si surface has proven to be vital for the understanding of the growth process. The knowledge of the interfacial binding principles has also allowed us to propose a way to engineer the band-offsets between the oxide and the silicon substrate. The results obtained for the Si substrate are directly transferable to Ge.
    12/2007: pages 165-179;
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    ABSTRACT: First-principles calculations based on density-functional theory (DFT) were performed on RPt3Si (R=Pr, Nd, Sm) for the first time. The electronic density of states (DOS) and bonding properties were studied using relativistic full-potential APW plus local orbitals calculations. The crystal-field (CF) splitting was derived for NdPt3Si and SmPt3Si by fitting the temperature-dependent magnetic susceptibility. The starting estimate of the CF parameters for fitting procedure was obtained from first-principles calculations based on DFT.
    Physica B Condensed Matter 11/2007; 400(1-2):114-118. DOI:10.1016/j.physb.2007.06.025 · 1.32 Impact Factor
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    ABSTRACT: Electronic structure calculations were performed on the compound BaCoO3. A-type antiferromagnetism is predicted as a ground state, with a very small Néel temperature, consistent with experiment. The insulating behavior of the compound needs symmetry breaking and occurs via an in-chain orbital ordering. The origin of this orbital ordering is explained. A large value of the orbital angular momentum is estimated, with the z axis being the easy direction for the magnetization. A large, Ising-type, magnetocrystalline anisotropy is calculated for this quasi-one-dimensional compound, consistent with the collinear magnetic structure predicted.
    Physical Review B 10/2007; 76(16). DOI:10.1103/PhysRevB.76.165120 · 3.74 Impact Factor
  • S. J. Sferco · P. Blaha · K. Schwarz
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    ABSTRACT: The multilayer relaxations of pure Al(001) surface were theoretically analyzed using ab initio all-electron calculations. Big slabs (23 atomic layers+20 vacuum layers) were needed to capture the deep pattern of multilayer relaxations. We have obtained an outward relaxation for the surface interlayer distance and deep interlayer relaxations characterized by a damped oscillation wave pattern, with several interlayers by cycle. The first three interlayers were found to be expanded, while the following four interlayers were found to be contracted. A charge density analysis allows us to correlate the outward relaxation with the population imbalance between the atomiclike p‖ and p⊥ orbitals of atoms at the surface. Multilayer relaxations are related to the presence of distributed Friedel oscillations in the charge density difference between bulk and bulk-truncated slabs. Work function and surface energy results are also presented and discussed. In order to calculate the latter, a high precision Al bulk energy value was obtained irrespective of whether it is calculated from the fcc symmetry or slab derived when the same method-dependent parameters as well as big slabs are used. Error bars, as a measure of the theoretical precision, are included for all studied properties. Our results agree with the available experimental measurements and, partially, with other theoretical calculations. Previous experimental work on this surface has never considered the possibility of such deep relaxations. Our results should motivate further experimental research on the multilayer relaxations of the Al(001) surface.
    Physical Review B 08/2007; 76(7). DOI:10.1103/PhysRevB.76.075428 · 3.74 Impact Factor
  • Zeitschrift für anorganische Chemie 09/2006; 632(12-13):2075-2075. DOI:10.1002/zaac.200670003 · 1.16 Impact Factor

Publication Stats

7k Citations
342.85 Total Impact Points


  • 1978–2015
    • Vienna University of Technology
      • • Institute of Materials Chemistry
      • • Institute of Solid State Physics
      • • Institute of Theoretical Physics
      • • Institute of Chemical Technology, Environmental Technology and Life Sciences
      Wien, Vienna, Austria
  • 2010
    • University of Amsterdam
      • Van der Waals-Zeeman Institute
      Amsterdamo, North Holland, Netherlands
  • 2006
    • Technische Universität Clausthal
      • Department of Theoretical Physics
      Bergstadt-Clausthal-Zellerfeld, Lower Saxony, Germany
  • 2004
    • The University of Warwick
      • Department of Physics
      Coventry, England, United Kingdom
  • 2001
    • Pädagogische Hochschule Wien
      Wien, Vienna, Austria
    • Medical School Hamburg
      Hamburg, Hamburg, Germany
  • 1998
    • Karl-Franzens-Universität Graz
      • Institute of Physics
      Graz, Styria, Austria
  • 1971–1998
    • University of Vienna
      • Institut für Physikalische Chemie
      Wien, Vienna, Austria
  • 1997
    • Arizona State University
      Phoenix, Arizona, United States
  • 1986
    • University of Birmingham
      Birmingham, England, United Kingdom
    • University of St Andrews
      Saint Andrews, Scotland, United Kingdom