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Author Verberck, B.; Michel, K.H.; Nikolaev, A.V.
Title The C60 molecules in (C60)N@SWCNT peapods: crystal field, intermolecular interactions and dynamics Type A1 Journal article
Year 2006 Publication Fullerenes, nanotubes, and carbon nanostructures Abbreviated Journal Fuller Nanotub Car N
Volume 14 Issue 2/3 Pages 171-178
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000238762900006 Publication Date 2006-06-08
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 (up) 10 Open Access
Notes Approved Most recent IF: 1.35; 2006 IF: 0.462
Call Number UA @ lucian @ c:irua:60025 Serial 3518
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Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Theoretical model for the structural phase transition at the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2002 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 66 Issue 16 Pages 165425-165425,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The recently discovered structural transition in polymerized KC60 at about 50 K results in a doubling of the unit cell volume and accompanies the 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 small orientational charge density waves along the polymer chains and concomitant displacements of the surrounding K+ ions. The effect is specific for the space group Pmnn of KC60 and is absent in RbC60 and CsC60 (space group I2/m). The mechanism is relevant for the metal-insulator transition.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000179286400135 Publication Date 2002-10-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited (up) 10 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number UA @ lucian @ c:irua:94907 Serial 3608
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Author Michel, K.H.; Verberck, B.
Title Theoretical phonon dispersions in monolayers and multilayers of hexagonal boron-nitride Type A1 Journal article
Year 2009 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 246 Issue 11/12 Pages 2802-2805
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from an empirical force constant model of valence interactions and calculating by Ewald's method the electrostatic force constants, we derive the dynamical matrix for a monolayer and for multilayer systems of hexagonal boron nitride (h-BN). Solution of the secular problem leads to the corresponding phonon dispersion relations. The interplay between valence forces and Coulomb forces is discussed. A comparison with previous results on graphene and graphene multilayers is made. Our spectra on the h-BN monolayer are rather similar to previous ab initio theory results. Comparison is also made with Raman and infrared experimental results.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000272904100091 Publication Date 2009-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited (up) 10 Open Access
Notes Approved Most recent IF: 1.674; 2009 IF: 1.150
Call Number UA @ lucian @ c:irua:80673 Serial 3609
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Author Tsvyashchenko, A.V.; Nikolaev, A.V.; Velichkov, A.I.; Salamatin, A.V.; Fomicheva, L.N.; Ryasny, G.K.; Sorokin, A.A.; Kochetov, O.I.; Budzynski, M.; Michel, K.H.
Title Lowering of the spatial symmetry at the gamma ->alpha phase transition in cerium Type A1 Journal article
Year 2010 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 82 Issue 9 Pages 1-4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using time-differential perturbed angular correlation spectroscopy we have measured the electric field gradient (EFG) at 111Cd probe nuclei in solid Ce in a pressure range up to 8 GPa. Covering various allotropic phases of Ce, we find that the value of the EFG in the cubic α phase is almost four times larger than in the cubic γ phase and close to values in the noncubic phases α′ and α″. These results together with the differences in time modulation of the spectra are interpreted as evidence for quadrupolar electronic charge-density ordering and symmetry lowering at the γ→α transition while the lattice remains face-centered cubic
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000282004400001 Publication Date 2010-09-16
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 (up) 11 Open Access
Notes ; This work is supported by the Program of the Presidium of the Russian Academy of Sciences “Physics of Strongly Compressed Matter.” We are grateful to S. M. Stishov, B. Verberck, A. N. Grum-Grzhimailo, V. B. Brudanin and G. Heger for support of this work and discussion of the results. ; Approved Most recent IF: 3.836; 2010 IF: 3.774
Call Number UA @ lucian @ c:irua:85464 Serial 1854
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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 (up) 11 Open Access
Notes Approved Most recent IF: 2.965; 2005 IF: 3.138
Call Number UA @ lucian @ c:irua:102740 Serial 3377
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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 (up) 12 Open Access
Notes Approved Most recent IF: 2.965; 2002 IF: 2.998
Call Number UA @ lucian @ c:irua:103350 Serial 578
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Author Mattauch, S.; Heger, G.; Michel, K.H.
Title High resolution neutron and X-ray diffraction studies as a function of temperature and electric field of the ferroelectric phase transition of RDP Type A1 Journal article
Year 2004 Publication Crystal research and technology Abbreviated Journal Cryst Res Technol
Volume 39 Issue 12 Pages 1027-1054
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Neutron and high resolution X-ray diffraction investigations on perfect single crystals of RbH2PO4 (RDP), a hydrogen bonded ferroelectric of KDP type are reported. The results of crystal structure analysis from diffraction data, below and above the paraelectric – ferroelectric phase transition, support a disorder – order character Of [PO4H2](-)-groups. The tetragonal symmetry of the paraelectric phase with the double well potential of the hydrogen atoms obtained by diffraction, results simply from a time-space average of orthorhombic symmetry. According to the group – subgroup relation between the tetragonal space group 142d and the orthorhombic Fdd2 a short range order of ferroelectric clusters in the tetragonal phase is observed. With decreasing temperature the ferroelectric clusters increase and the long range interaction between their local polarisation vectors leads to the formation of lamellar ferroelectric domains with alternating polarisation directions at T-C = 147 K. From the high resolution X-ray data it is concluded that below T-C the ferroelastic strain in the (a,b)-plane leads to micro-angle grain boundaries at the domain walls. The tilt angle is enhanced by an applied electric field parallel to the ferroelectric axis. The resulting dislocations at the domain walls persist in the paraelectric phase leading to a memory effect for the arrangement of twin lamellae. With increased electric field the phase transition temperature T-C is decreased.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000225681100001 Publication Date 2004-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0232-1300;1521-4079; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1 Times cited (up) 12 Open Access
Notes Approved Most recent IF: 1; 2004 IF: 0.770
Call Number UA @ lucian @ c:irua:94785 Serial 1459
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Author Michel, K.H.; Verberck, B.
Title Theory of phonon dispersions and piezoelectricity in multilayers of hexagonal boron-nitride Type A1 Journal article
Year 2011 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 248 Issue 11 Pages 2720-2723
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Taking into account covalent, Coulomb and van der Waals interactions, we construct the dynamical matrix and calculate the phonon dispersion relations for multilayer crystals of hexagonal boron-nitride. Coulomb interactions account for a strong overbending of optical phonons. Applying and extending Born's long-wave theory to the case of multilayer crystals, we calculate the piezoelectric stress constant equation image as a function of the number of layers equation image. In agreement with group theory, we find that equation image for equation image even; for an uneven number equation image of layers we obtain equation image, i.e. the piezoelectric constant decreases as equation image.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000297517100069 Publication Date 2011-10-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited (up) 13 Open Access
Notes ; Discussions with G. Heger, B. Partoens and F. M. Peeters are gratefully acknowledged. This work has been supported by the Flemish Science Foundation (FWO-Vl) and the Bijzonder Onderzoeksfonds, Universiteit Antwerpen (BOF-UA). ; Approved Most recent IF: 1.674; 2011 IF: 1.316
Call Number UA @ lucian @ c:irua:94034 Serial 3618
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Author Nikolaev, A.V.; Prassides, K.; Michel, K.H.
Title Charge transfer and polymer phases in AC60 (A=K, Rb, Cs) fullerides Type A1 Journal article
Year 1998 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 108 Issue Pages 4912-4923
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000072588400025 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 (up) 14 Open Access
Notes Approved Most recent IF: 2.965; 1998 IF: 3.147
Call Number UA @ lucian @ c:irua:23985 Serial 338
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Author Michel, K.H.; Lamoen, D.; David, W.I.F.
Title Orientational order and disorder in solid C60 : theory and diffraction experiments Type A1 Journal article
Year 1995 Publication Acta crystallographica: section A: foundations of crystallography Abbreviated Journal Acta Crystallogr A
Volume 51 Issue 3 Pages 365-374
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from a microscope model of the intermolecular potential, a unified description is presented of the Bragg scattering law in the orientationally disordered and in the ordered phase of solid C-60. The orientational structure factor is expanded in terms of symmetry-adapted surface harmonics. The expansion coefficients are calculated from theory and compared with experiment Their temperature evolution is studied in the disordered phase at the 260 K transitions and in the ordered phase. In the ordered phase, new results from high-resolution neutron powder diffraction are given. In the disordered phase, space group Fm $($) over bar$$ 3m, the reflections have A(1g) symmetry; in the ordered phase, space group Pa $$($) over bar 3, reflections of T-2g symmetry appear and in addition the A(1g) reflections are renormalized. The orientational density distribution is calculated. The effective crystal-field potential is constructed, its temperature evolution in the ordered phase is studied and related to the occurrence of an orientational glass.
Address
Corporate Author Thesis
Publisher Place of Publication Copenhagen Editor
Language Wos A1995RB59400018 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0108-7673; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.307 Times cited (up) 14 Open Access
Notes Approved CHEMISTRY, MULTIDISCIPLINARY 65/163 Q2 # CRYSTALLOGRAPHY 10/26 Q2 #
Call Number UA @ lucian @ c:irua:12189 Serial 2518
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Author Michel, K.H.
Title Sequence of orientational phase transitions in solid C60 Type A1 Journal article
Year 1992 Publication Chemical physics letters Abbreviated Journal Chem Phys Lett
Volume 193 Issue Pages 478-480
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1992HZ32900006 Publication Date 2002-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0009-2614; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.897 Times cited (up) 14 Open Access
Notes Approved MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 #
Call Number UA @ lucian @ c:irua:2971 Serial 2985
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Author Michel, K.H.; Verberck, B.; Hulman, M.; Kuzmany, H.; Krause, M.
Title Superposition of quantum and classical rotational motions in Sc2C2@C84 fullerite Type A1 Journal article
Year 2007 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 126 Issue 6 Pages 064304,1-15
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000244250200008 Publication Date 2007-02-09
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 (up) 14 Open Access
Notes Approved Most recent IF: 2.965; 2007 IF: 3.044
Call Number UA @ lucian @ c:irua:63628 Serial 3381
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Author Nikolaev, A.V.; Michel, K.H.
Title Symmetry lowering at the structural phase transitions in NpO2 and UO2 Type A1 Journal article
Year 2003 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 68 Issue 5 Pages 054112-054112,7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The structural phase transitions with electric-quadrupole long-range order in NpO2 (Fm (3) over barm-->Pn (3) over barm) and UO2 (Fm (3) over barm-->Pa (3) over bar) are analyzed from a group theoretical point of view. In both cases, the symmetry lowering involves three quadrupolar components belonging to the irreducible representation T-2g (Gamma(5)) of O-h and condensing in a triple-q structure at the X point of the Brillouin zone. The Pa (3) over bar structure is close to Pn (3) over barm, but allows for oxygen displacements. The Pa (3) over bar ordering leads to an effective electrostatic attraction between electronic quadrupoles while the Pn (3) over barm ordering results in a repulsion between them. It is concluded that the Pn (3) over barm structure can be stabilized only through some additional process such as strengthening of the chemical bonding between Np and O. We also derive the relevant structure-factor amplitudes for Pn (3) over barm and Pa (3) over bar, and the effect of domains on resonant x-ray scattering experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000185240100038 Publication Date 2003-08-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited (up) 15 Open Access
Notes Approved Most recent IF: 3.836; 2003 IF: NA
Call Number UA @ lucian @ c:irua:94847 Serial 3405
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Author Michel, K.H.; Nikolaev, A.V.
Title Theory of distinct crystal structures of polymerized fullerides AC60, A=K, Rb, Cs: the specific role of alkalis Type A1 Journal article
Year 2000 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 85 Issue Pages 3197-3200
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000089807800033 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007;1079-7114; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited (up) 16 Open Access
Notes Approved Most recent IF: 8.462; 2000 IF: 6.462
Call Number UA @ lucian @ c:irua:34339 Serial 3615
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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 (up) 16 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836
Call Number UA @ admin @ c:irua:159346 Serial 5225
Permanent link to this record
 

 
Author Nikolaev, A.V.; Michel, K.H.
Title Quantum charge density fluctuations and the γ-α phase transition in Ce Type A1 Journal article
Year 1999 Publication European physical journal : B : condensed matter and complex systems Abbreviated Journal Eur Phys J B
Volume 9 Issue Pages 619-634
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000081615500009 Publication Date 2002-08-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6028; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.461 Times cited (up) 19 Open Access
Notes Approved Most recent IF: 1.461; 1999 IF: 1.705
Call Number UA @ lucian @ c:irua:28504 Serial 2774
Permanent link to this record
 

 
Author Callebaut, A.K.; Michel, K.H.
Title Microscopic theory of orientational disorder and lattice instability in solid C70 Type A1 Journal article
Year 1995 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 52 Issue 21 Pages 15279-15290
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We have developed a microscopic theory which describes the orientational dynamics of C-70 molecules and its coupling to lattice displacements in the face-centered-cubic phase of C-70 fullerite. The single-molecule orientational density distribution in the disordered phase is calculated. The ferroelastic transition to the rhombohedral phase is investigated. The discontinuity of the orientational order parameter at the phase transition is calculated. It is found that the transition leads to a stretching of the primitive unit cell along a [111] cubic direction. A softening of the elastic constant c(44) at the transition is predicted.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1995TK97900042 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.736 Times cited (up) 20 Open Access
Notes Approved PHYSICS, APPLIED 28/145 Q1 #
Call Number UA @ lucian @ c:irua:104421 Serial 2031
Permanent link to this record
 

 
Author Michel, K.H.
Title Molecular structure and orientational ordering in solid C60 Type A1 Journal article
Year 1992 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 97 Issue 7 Pages 5155-5162
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A microscopic theory, which describes the orientational dynamics of C60 molecules in the face-centered cubic phase of C60-fullerite, is formulated or the case of a complex molecular structure. Interaction centers which comprise atoms, double bonds, and single bonds as molecular constituents contribute to the intermolecular potential. Orientation dependent physical properties are described in terms of symmetry-adapted rotator functions. It is found that a same set of rotator functions is sufficient even in the case of a complex molecular structure. Phase transition temperatures are discussed for various models of molecular structure.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos A1992JR33800062 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 2.952 Times cited (up) 20 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:2973 Serial 2185
Permanent link to this record
 

 
Author Michel, K.H.; Copley, J.R.D.
Title Orientational mode coupling, diffuse scattering, and the order-disorder phase transition in solid C60 Type A3 Journal article
Year 1997 Publication Zeitschrift für Physik: B: condensed matter and quanta Abbreviated Journal
Volume 103 Issue Pages 369-376
Keywords A3 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos A1997XL52100005 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0340-224x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited (up) 21 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:21181 Serial 2517
Permanent link to this record
 

 
Author Michel, K.H.; Costamagna; Peeters, F.M.
Title Theory of thermal expansion in 2D crystals Type A1 Journal article
Year 2015 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 252 Issue 252 Pages 2433-2437
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The thermal expansion alpha(T) in layered crystals is of fundamental and technological interest. As suggested by I. M. Lifshitz in 1952, in thin solid films (crystalline membranes) a negative contribution to alpha(T) is due to anharmonic couplings between in-plane stretching modes and out-of-plane bending (flexural modes). Genuine in-plane anharmonicities give a positive contribution to alpha(T). The competition between these two effects can lead to a change of sign (crossover) from a negative value of alpha(T) in a temperature (T) range T <= T-alpha to a positive value of alpha(T) for T > T-alpha in layered crystals. Here, we present an analytical lattice dynamical theory of these phenomena for a two-dimensional (2D) hexagonal crystal. We start from a Hamiltonian that comprises anharmonic terms of third and fourth order in the lattice displacements. The in-plane and out-of-plane contributions to the thermal expansion are studied as functions of T for crystals of different sizes. Besides, renormalization of the flexural mode frequencies plays a crucial role in determining the crossover temperature T-alpha. Numerical examples are given for graphene where the anharmonic couplings are determined from experiments. The theory is applicable to other layer crystals wherever the anharmonic couplings are known. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000364690400014 Publication Date 2015-08-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited (up) 21 Open Access
Notes ; We thank B. Verberck, D. Lamoen, and A. Dobry for useful comments. We acknowledge funding from the FWO (Belgium)-MINCyT (Argentina) collaborative research project. This work is supported by the Euro GRAPHENE project CONGRAN. ; Approved Most recent IF: 1.674; 2015 IF: 1.489
Call Number UA @ lucian @ c:irua:130281 Serial 4264
Permanent link to this record
 

 
Author Verberck, B.; Michel, K.H.
Title Nanotube field and orientational properties of C70 molecules in carbon nanotubes Type A1 Journal article
Year 2007 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 75 Issue 4 Pages 045419,1-14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The orientation of a C(70) fullerene molecule encapsulated in a single-walled carbon nanotube (SWCNT) depends on the tube radius. First we confirm that chirality effects do not affect the orientation as well by comparing discrete atomistic calculations with the results of a continuous tube approximation for a variety of SWCNTs. The molecular and the tube symmetry are exploited by using symmetry-adapted rotator functions. We accurately determine the optimal molecular orientation as a function of the tube radius; for low (less than or similar to 7 A) and high (greater than or similar to 7.2 A) tube radii, lying and standing molecular orientations are recovered, respectively. In between, we observe a transition regime. In addition, we consider off-axis positions. We perform a one-dimensional liquid description of a chain of on-axis C(70) molecules inside a SWCNT. All results agree well with recent x-ray diffraction experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000243895600128 Publication Date 2007-01-17
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 (up) 23 Open Access
Notes Approved Most recent IF: 3.836; 2007 IF: 3.172
Call Number UA @ lucian @ c:irua:63752 Serial 2280
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Author Lamoen, D.; Michel, K.H.
Title Crystal field and molecular structure of solid C60 Type A1 Journal article
Year 1993 Publication Zeitschrift für Physik : B : condensed matter Abbreviated Journal
Volume 92 Issue Pages 323-330
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The crystal field in the orientationally disordered phase of C90-fullerite is derived from an intermolecular potential model, which takes into account the geometric difference between double bonds and single bonds. The molecules are modelled as rigid bodies, atoms and single bonds are treated as single interaction centers, while double bonds are described by a distribution of interaction centers along the bond. The crystal field is expanded in terms of cubic rotator functions. The calculated expansion coefficients are compared with empirical values derived from diffraction data. The angular dependence of the crystal field, resulting from an anticlockwise rotation of the molecule around the [111] axis, exhibits an absolute and a secondary minimum at angles of 98-degrees and 38-degrees respectively. The self interaction of the molecule in a deformable lattice is investigated.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos A1993MC88000005 Publication Date 2005-03-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0722-3277;1434-6036; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited (up) 25 Open Access
Notes Approved PHYSICS, CONDENSED MATTER 11/54 Q1 #
Call Number UA @ lucian @ c:irua:5777 Serial 553
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Author Michel, K.H.; Verberck, B.; Nikolaev, A.V.
Title Nanotube field and one-dimensional fluctuations of C60 molecules in carbon nanotubes Type A1 Journal article
Year 2005 Publication European physical journal : B : condensed matter and complex systems Abbreviated Journal Eur Phys J B
Volume 48 Issue 1 Pages 113-124
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000233998600016 Publication Date 2005-12-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6028;1434-6036; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.461 Times cited (up) 25 Open Access
Notes Approved Most recent IF: 1.461; 2005 IF: 1.720
Call Number UA @ lucian @ c:irua:56408 Serial 2279
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Author Michel, K.H.; Çakir, D.; Sevik, C.; Peeters, F.M.
Title Piezoelectricity in two-dimensional materials : comparative study between lattice dynamics and ab initio calculations Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 95 Issue 95 Pages 125415
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The elastic constant C-11 and piezoelectric stress constant e(1),(11) of two-dimensional (2D) dielectric materials comprising h-BN, 2H-MoS2, and other transition-metal dichalcogenides and dioxides are calculated using lattice dynamical theory. The results are compared with corresponding quantities obtained with ab initio calculations. We identify the difference between clamped-ion and relaxed-ion contributions with the dependence on inner strains which are due to the relative displacements of the ions in the unit cell. Lattice dynamics allows us to express the inner-strain contributions in terms of microscopic quantities such as effective ionic charges and optoacoustical couplings, which allows us to clarify differences in the piezoelectric behavior between h-BN and MoS2. Trends in the different microscopic quantities as functions of atomic composition are discussed.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000396013400005 Publication Date 2017-03-11
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 (up) 29 Open Access
Notes ; The authors acknowledge useful discussions with L. Wirtz and A. Molina-Sanchez. This work was supported by the Methusalem program and the Fonds voor Wetenschappelijk Onderzoek-Vlaanderen. Computational resources were provided by HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules foundation. ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:142444 Serial 4603
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Author Verberck, B.; Michel, K.H.
Title Nanotube field of C60 molecules in carbon nanotubes: atomistic versus continuous approach Type A1 Journal article
Year 2006 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 74 Issue 4 Pages 045421,1-14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000239426800113 Publication Date 2006-07-22
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 (up) 31 Open Access
Notes Approved Most recent IF: 3.836; 2006 IF: 3.107
Call Number UA @ lucian @ c:irua:60090 Serial 2281
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Author Lamoen, D.; Michel, K.H.
Title Microscopic theory of thermoelastic phenomena and pressure dependence in solid C60 Type A1 Journal article
Year 1993 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 48 Issue 2 Pages 807-813
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A microscopic theory for the coupling of molecular orientations with acoustic lattice displacements is proposed. The relevant interaction is quadratic in the orientational-order-parameter variables and linear in longitudinal strains. The coupling is evaluated for a complex molecular structure. The intermolecular potential is obtained from interaction centers placed at nuclei and at the centers of interatomic bonds. The free energy is derived and the experimental consequences of the theory are studied. The Clausius-Clapeyron equation for orientational melting is obtained. The theory explains the decrease of the lattice constant at the first-order phase transition and the increase of the transition temperature with applied pressure.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1993LM88500014 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.736 Times cited (up) 32 Open Access
Notes Approved PHYSICS, CONDENSED MATTER 16/67 Q1 #
Call Number UA @ lucian @ c:irua:5779 Serial 2035
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Author Bostoen, C.; Michel, K.H.
Title Dynamics of a quadrupolar glass Type A1 Journal article
Year 1991 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 43 Issue Pages 4415-4422
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1991EX92100073 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 0163-1829 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.736 Times cited (up) 33 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:939 Serial 773
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Author Michel, K.H.
Title Free energy and orientational phase transition in solid C60 Type A1 Journal article
Year 1992 Publication Zeitschrift für Physik: B Abbreviated Journal
Volume 88 Issue Pages 71-78
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos A1992JB10700009 Publication Date 2005-04-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0722-3277;1434-6036; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited (up) 33 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:2967 Serial 1275
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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 Pages 4353-4370
Keywords A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos A1993LK74100008 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.346 Times cited (up) 34 Open Access
Notes Approved MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 #
Call Number UA @ lucian @ c:irua:5778 Serial 2297
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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 (up) 34 Open Access
Notes Approved MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 #
Call Number UA @ lucian @ c:irua:102972 Serial 2298
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