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Author Bussmann-Holder, A.; Michel, K.H.
Title Proton tunneling and nonlinear polarizability effects in hydrogen-bonded ferroelectrics Type P1 Proceeding
Year 1998 Publication AIP conference proceedings T2 – 5th Williamsburg Workshop on 1st-Principles Calculations for, Ferroelectrics, FEB 01-04, 1998, WILLIAMSBURG, VA Abbreviated Journal
Volume Issue Pages 202-206
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract Hydrogen-bonded ferroelectrics are modelled by a coupled spin/nonlinear lattice (polarizability) interaction Hamiltonian, where specifically the geometry of the hydrogen bond is included. The model leads to a structural phase transition and describes correctly the isotope effect due to the substitution H/D in hydrogen-bonded systems in terms of bond length changes.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos 000075034000022 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue 436 Edition
ISSN 1-56396-730-8 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:104344 Serial 2733
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Author Nikolaev, A.V.; Michel, K.H.
Title Many electron- and hole terms of molecular ions C60n\pm Type A1 Journal article
Year 2003 Publication Coupling In Chemistry And Physics Abbreviated Journal Adv Quantum Chem
Volume 44 Issue Pages 305-312
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000188940800019 Publication Date 2004-05-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0065-3276; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.196 Times cited 1 Open Access
Notes Approved Most recent IF: 1.196; 2003 IF: 0.375
Call Number (down) UA @ lucian @ c:irua:104131 Serial 1942
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Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Orientational charge density waves and the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2005 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 71 Issue 16 Pages 165117-11
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A theoretical model is presented for the description of the metal-insulator transition which accompanies the structural phase transition at T approximate to 50 K in polymerized KC60. The model involves orientational charge density waves (along the C-60 polymer chains) which were introduced previously for a description of the structural phase transition. A satisfactory qualitative and quantitative understanding is obtained when the three-dimensionality of the crystal and the presence of the K+ counterions is properly taken into account.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000228763100035 Publication Date 2005-04-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 1 Open Access
Notes Approved Most recent IF: 3.836; 2005 IF: 3.185
Call Number (down) UA @ lucian @ c:irua:104076 Serial 2514
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Author Nikolaev, A.V.; Michel, K.H.
Title Molecular terms and optical transitions of C60n+/- molecular ions Type P1 Proceeding
Year 2002 Publication AIP conference proceedings T2 – 16th International Winterschool on Electronic Properties of Novel, Materials, MAR 02-09, 2002, KIRCHBERG, AUSTRIA Abbreviated Journal
Volume Issue Pages 417-420
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract We have studied the molecular energy terms of the hole configurations (h(u)(+))(m), m=2,3,4,5 of C-60(m+) cations and the electronic configurations (t(1u))(n) n=2,3,4, as well as (t(1u))(n-1)t(1g) of the C-60(n-) anions. The lowest terms (within an energy span of 0.03 eV) for C-60(2+) are three triplets T-3(1g), (3)G(g), T-3(2g) and for C-60(3+) are three quartets T-4(1u), (4)G(u), T-4(2u), which favor Jahn-Teller distortions. For the ground state of C-60(2-) we find a triplet T-3(1g) in agreement with Hund's rules. Our method takes into account intramolecular direct and exchange multipolar Coulomb interactions.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume 633 Series Issue Edition
ISSN 0-7354-0088-1 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:103905 Serial 2187
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Author Nikolaev, A.V.; Michel, K.H.
Title Ab initio approach to superexchange interactions in alkali doped fullerides AC60 Type P1 Proceeding
Year 2004 Publication AIP conference proceedings T2 – 18th International Winterschool/Euroconference on Electronic Properties, of Novel Materials, MAR 06-JUN 13, 2004, Kirchberg, AUSTRIA Abbreviated Journal
Volume Issue Pages 393-396
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract The superexchange interactions between the fullerenes arise as a result of the electron transfer from the C-60 molecule to the alkali atom and back. We present a scheme, which is a configuration interaction approach based on the valence bond (Heitler-London) method. The effect of superexchange is described together with chemical bonding by constructing and solving a secular equation, rather than by using a perturbation treatment. We have considered 180degrees and 90degrees superexchange for the C-60 Cs-C-60 pathways. The calculations account for unusual electronic properties of polymer orthorhombic and quenched cubic phases of CsC60: two lines in nuclear magnetic resonance experiments, the development of a spin-singlet ground state and a decrease of magnetic susceptibility as T-->0.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos 000224699400085 Publication Date 2004-11-11
Series Editor Series Title Abbreviated Series Title
Series Volume 723 Series Issue Edition
ISSN 0-7354-0204-3 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:103752 Serial 27
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Author Bussmann-Holder, A.; Dalal, N.; Michel, K.H.
Title Polarizability induced cooperative proton ordering, coexistence of order/disorder and displacive dynamics and isotope effects in hydrogen-bonded systems Type A1 Journal article
Year 2000 Publication The journal of physics and chemistry of solids T2 – Williamsburg Workshop on Ferroelectrics 99, JAN 31-FEB 03, 1999, WILLIAMSBURG, VIRGINIA Abbreviated Journal J Phys Chem Solids
Volume 61 Issue 2 Pages 271-274
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Despite the general belief that hydrogen-bonded ferro- and antiferroelectrics undergo a pure order/disorder transition at the structural instability, new NMR data and a new theoretical concept yield convincing evidence that a pronounced displacive component is present in these systems, which modifies substantially the temperature dependencies of the tunnel and lattice mode frequencies. The experiments and their interpretation are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.
Address
Corporate Author Thesis
Publisher Pergamon-elsevier science ltd Place of Publication Oxford Editor
Language Wos 000084147000020 Publication Date 2002-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3697; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.059 Times cited 8 Open Access
Notes Approved Most recent IF: 2.059; 2000 IF: 1.003
Call Number (down) UA @ lucian @ c:irua:103469 Serial 2660
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Author Verberck, B.; Michel, K.H.; Nikolaev, A.V.
Title Crystal structures of polymerized fullerides AC60, A=K, Rb, Cs, and alkali-mediated interactions Type A1 Journal article
Year 2002 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 116 Issue 23 Pages 10462-10474
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from a model of rigid interacting C-60 polymer chains on an orthorhombic lattice, we study the mutual orientation of the chains and the stability of the crystalline structures Pmnn and I2/m. We take into account (i) van der Waals interactions and electric quadrupole interactions between C-60 monomers on different chains as well as (ii) interactions of the monomers with the surrounding alkali atoms. The direct interactions (i) always lead to an antiferrorotational structure Pmnn with alternate orientation of the C-60 chains in planes (001). The interactions (ii) with the alkalis consist of two parts: translation-rotation (TR) coupling where the orientations of the chains interact with displacements of the alkalis, and quadrupolar electronic polarizability (ep) coupling, where the electric quadrupoles on the C-60 monomers interact with induced quadrupoles due to excited electronic d-states of the alkalis. Both interactions (ii) lead to an effective orientation-orientation interaction between the C-60 chains and always favor the ferrorotational structure I2/m, where C-60 chains have a same orientation. The structures Pmnn for KC60 and I2/m for Rb- and CsC60 are the result of a competition between the direct interaction (i) and the alkali-mediated interactions (ii). In Rb- and CsC60 the latter are found to be dominant, the preponderant role being played by the quadrupolar electronic polarizability of the alkali ions. (C) 2002 American Institute of Physics.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000175905800044 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-9606; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.965 Times cited 12 Open Access
Notes Approved Most recent IF: 2.965; 2002 IF: 2.998
Call Number (down) UA @ lucian @ c:irua:103350 Serial 578
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Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Theoretical model for the structural phase transition and the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2004 Publication Fullerenes, nanotubes, and carbon nanostructures T2 – 6th Biennial International Workshop on Fullerenes and Atomic Clusters, JUN 30-JUL 04, 2003, St Petersburg, RUSSIA Abbreviated Journal Fuller Nanotub Car N
Volume 12 Issue 1-2 Pages 243-252
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The recently discovered structural phase transition in Polymerized KC60 at about 50K leads to a doubling of the unit cell volume and is accompanied by a metal-insulator transition. Here, we show that the ((a) over right arrow + (c) over right arrow, (b) over right arrow, (a) over right arrow – (c) over right arrow) superstructure results from orientational charge density waves along the polymer chains and correlated displacements of the K+ ions. The presented model can also account for the metal-insulator transition. The effect is specific for the space group Pmnn of KC60 and is absent in both Rb- and CsC60 (space group 12/m), in agreement with the present experimental knowledge of these compounds.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000220551600040 Publication Date 2004-03-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1536-383X;1536-4046; ISBN Additional Links UA library record; WoS full record
Impact Factor 1.35 Times cited Open Access
Notes Approved Most recent IF: 1.35; 2004 IF: 1.117
Call Number (down) UA @ lucian @ c:irua:103259 Serial 3607
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Author Copley, J.R.D.; Michel, K.H.
Title Neutron and X-ray-scattering cross sections of orientationally disordered solid C60 Type A1 Journal article
Year 1993 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 5 Issue 26 Pages 4353-4370
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Differential cross sections for neutron and x-ray scattering have been derived for the orientationally disordered phase of solid C60. Interaction centres are placed at nuclei and at the centres of interatomic bonds. Bragg and diffuse scattering cross sections, for single crystals and for powders, are formulated using symmetry-adapted rotator functions. Thermal averages are calculated taking account of crystal field effects. Thermally averaged orientational distribution functions have also been calculated.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos A1993LK74100008 Publication Date 2002-08-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.346 Times cited 34 Open Access
Notes Approved MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 #
Call Number (down) UA @ lucian @ c:irua:102972 Serial 2298
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Author Bussmann-Holder, A.; Michel, K.H.
Title The isotope effect in hydrogen-bonded systems Type A1 Journal article
Year 1998 Publication International journal of modern physics: B: condensed matter physics, statistical physics, applied physics T2 – 1st International Conference on New Theories, Discoveries, and, Applications of Superconductors and Related Materials (New3SC-1), FEB 19-24, 19 Abbreviated Journal Int J Mod Phys B
Volume 12 Issue 29-31 Pages 3406-3408
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The giant isotope effect on the ferro- and antiferroelectric transition temperature upon deuteration of hydrogen-bonded systems is well known experimentally since various decades. Yet, theoretically only recently a microscopic understanding of this effect has been achieved which, specifically, took into account the geometry of the O ... H ... O bond. The implications of this modeling are multiple as numerous hydrogen-bonded organic systems show the same effects as ferro- and antiferroelectrics, i.e., cooperative proton tunneling at a well-defined temperature.
Address
Corporate Author Thesis
Publisher Place of Publication Singapore Editor
Language Wos 000079114500104 Publication Date 2003-10-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0217-9792;1793-6578; ISBN Additional Links UA library record; WoS full record
Impact Factor 0.736 Times cited Open Access
Notes Approved Most recent IF: 0.736; 1998 IF: 0.987
Call Number (down) UA @ lucian @ c:irua:102920 Serial 3589
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Author Nikolaev, A.V.; Michel, K.H.
Title Superexchange and electron correlations in alkali fullerides AC60, A=K, Rb, Cs Type A1 Journal article
Year 2005 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 122 Issue 6 Pages 064310-64314
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Superexchange interactions in alkali fullerides AC(60) are derived for C-60 molecular ions separated by interstitial alkali-metal ions. We use a multiconfiguration approach which comprises the lowest molecular orbital states of the C-60 molecule and the excited s and d states of the alkali-metal atom A. Interactions are described by the valence bond (Heitler-London) method for a complex (C-60 – A – C-60) – with two valence electrons. The electronic charge transfer between the alkali-metal atom and a neighboring C-60 molecule is not complete. The occupation probability of excited d and s states of the alkali atom is not negligible. In correspondence with the relative positions of the C-60 molecules and A atoms in the polymer crystal, we consider 180degrees and 90degrees (angle) superexchange pathways. For the former case the ground state is found to be a spin singlet separated from a triplet at similar to20 K. For T < 20 K there appear strong spin correlations for the 180degrees superexchange pathway. The results are related to spin lattice relaxation experiments on CsC60 in the polymerized and in the quenched cubic phase. (C) 2005 American Institute of Physics.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000226918100018 Publication Date 2005-02-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-9606; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.965 Times cited 11 Open Access
Notes Approved Most recent IF: 2.965; 2005 IF: 3.138
Call Number (down) UA @ lucian @ c:irua:102740 Serial 3377
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Author Verberck, B.; Heresanu, V.; Rouziere, S.; Cambedouzou, J.; Launois, P.; Kovats, E.; Pekker, S.; Vliegenthart, G.A.; Michel, K.H.; Gompper, G.
Title Fullerene-cubane : X-ray scattering experiments and Monte Carlo simulations Type A1 Journal article
Year 2008 Publication Fullerenes, nanotubes, and carbon nanostructures T2 – 8th Biennial International Workshop on Fullerenes and Atomic Clusters, (IWFAC 2007), JUL 02-06, 2007, St Petersburg, RUSSIA Abbreviated Journal Fuller Nanotub Car N
Volume 16 Issue 5-6 Pages 293-300
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract We report single-crystal X-ray diffuse scattering measurements on C-60.C8H8 fullerene-cubane showing that the C-60 molecules are orientationally disordered at 300 and 150K and get ordered at low temperatures. Monte Carlo simulations provide further insight in the orientational behavior of both C-60 and C8H8 molecules; low-temperature molecular orientations are predicted.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000259645200003 Publication Date 2008-09-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1536-383X;1536-4046; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.35 Times cited 6 Open Access
Notes Approved Most recent IF: 1.35; 2008 IF: 0.680
Call Number (down) UA @ lucian @ c:irua:102640 Serial 1295
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Author Scuracchio, P.; Michel, K.H.; Peeters, F.M.
Title Phonon hydrodynamics, thermal conductivity, and second sound in two-dimensional crystals Type A1 Journal article
Year 2019 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 99 Issue 14 Pages 144303
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from our previous work in which we obtained a system of coupled integrodifferential equations for acoustic sound waves and phonon density fluctuations in two-dimensional (2D) crystals, we derive here the corresponding hydrodynamic equations, and we study their consequences as a function of temperature and frequency. These phenomena encompass propagation and damping of acoustic sound waves, diffusive heat conduction, second sound, and Poiseuille heat flow, all of which are characterized by specific transport coefficients. We calculate these coefficients by means of correlation functions without using the concept of relaxation time. Numerical calculations are performed as well in order to show the temperature dependence of the transport coefficients and of the thermal conductivity. As a consequence of thermal tension, mechanical and thermal phenomena are coupled. We calculate the dynamic susceptibilities for displacement and temperature fluctuations and study their resonances. Due to the thermomechanical coupling, the thermal resonances such as the Landau-Placzek peak and the second-sound doublet appear in the displacement susceptibility, and conversely the acoustic sound wave doublet appears in the temperature susceptibility, Our analytical results not only apply to graphene, but they are also valid for arbitrary 2D crystals with hexagonal symmetry, such as 2D hexagonal boron nitride, 2H-transition-metal dichalcogenides, and oxides.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000464717300006 Publication Date 2019-04-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 16 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836
Call Number (down) UA @ admin @ c:irua:159346 Serial 5225
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