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Author Michel, K.H.; Verberck, B.
Title Theory of elastic and piezoelectric effects in two-dimensional hexagonal boron nitride Type A1 Journal article
Year 2009 Publication Physical review : B : solid state Abbreviated Journal Phys Rev B
Volume 80 Issue 22 Pages (down) 224301,1-224301,10
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from an empirical force constant model of valence interactions and calculating by Ewalds method the ion-ion force constants, we derive the dynamical matrix for a monolayer crystal of hexagonal boron nitride (h-BN). The phonon dispersion relations are calculated. The interplay between valence and Coulomb forces is discussed. It is shown by analytical methods that the longitudinal and the transverse optical (LO and TO) phonon branches for in-plane motion are degenerate at the Γ point of the Brillouin zone. Away from Γ, the LO branch exhibits pronounced overbending. It is found that the nonanalytic Coulomb contribution to the dynamical matrix causes a linear increase of the LO branch with increasing wave vector starting at Γ. This effect is general for two-dimensional (2D) ionic crystals. Performing a long-wavelength expansion of the dynamical matrix, we use Borns perturbation method to calculate the elastic constants (tension coefficients). Since the crystal is noncentrosymmetric, internal displacements due to relative shifts between the two sublattices (B and N) contribute to the elastic constants. These internal displacements are responsible for piezoelectric and dielectric phenomena. The piezoelectric stress constant and the dielectric susceptibility of 2D h-BN are calculated.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000273228500045 Publication Date 2009-12-21
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 96 Open Access
Notes Approved Most recent IF: 3.836; 2009 IF: 3.475
Call Number UA @ lucian @ c:irua:80576 Serial 3616
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Author Beheshtian, J.; Sadeghi, A.; Neek-Amal, M.; Michel, K.H.; Peeters, F.M.
Title Induced polarization and electronic properties of carbon-doped boron nitride nanoribbons Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 86 Issue 19 Pages (down) 195433-195438
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The electronic properties of boron nitride nanoribbons (BNNRs) doped with a line of carbon atoms are investigated using density functional calculations. By replacing a line of alternating B and N atoms with carbons, three different configurations are possible depending on the type of the atoms which bond to the carbons. We found very different electronic properties for these configurations: (i) the NCB arrangement is strongly polarized with a large dipole moment having an unexpected direction, (ii) the BCB and NCN arrangements are nonpolar with zero dipole moment, (iii) the doping by a carbon line reduces the band gap regardless of the local arrangement of the borons and the nitrogens around the carbon line, and (iv) the polarization and energy gap of the carbon-doped BNNRs can be tuned by an electric field applied parallel to the carbon line. Similar effects were found when either an armchair or zigzag line of carbon was introduced.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000311694200006 Publication Date 2012-11-29
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 41 Open Access
Notes ; We would like to thank J. M. Pereira and S. Goedecker for helpful discussions. This work was supported by the Flemish Science Foundation (FWO-Vl), the ESF-EuroGRAPHENE project CONGRAN. M. N.-A is supported by EU-Marie Curie IIF postdoc Fellowship/299522. ; Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:105136 Serial 1603
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Author Michel, K.H.; Verberck, B.; Nikolaev, A.V.
Title Anisotropic packing and one-dimensional fluctuations of C60 molecules in carbon nanotubes Type A1 Journal article
Year 2005 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 95 Issue 18 Pages (down) 185506-185506,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The confinement of a C-60 molecule encapsulated in a cylindrical nanotube depends on the tube radius. In small tubes with radius R-T less than or similar to 7 A, a fivefold axis of the molecule coincides with the tube axis. The interaction between C-60 molecules in the nanotube is then described by a O-2-rotor model on a 1D liquid chain with coupling between orientational and displacive correlations. This coupling leads to chain contraction. The structure factor of the 1D liquid is derived. In tubes with a larger radius the molecular centers of mass are displaced off the tube axis. The distinction of two groups of peapods with on- and off-axis molecules suggests an explanation of the apparent splitting of A(g) modes of C-60 in nanotubes measured by resonant Raman scattering.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000232887400041 Publication Date 2005-10-28
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 40 Open Access
Notes Approved Most recent IF: 8.462; 2005 IF: 7.489
Call Number UA @ lucian @ c:irua:94717 Serial 127
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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 (down) 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 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 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 (down) 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 UA @ lucian @ c:irua:104076 Serial 2514
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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 (down) 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 13 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
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Author Michel, K.H.; Costamagna; Peeters, F.M.
Title Theory of anharmonic phonons in two-dimensional crystals Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages (down) 134302
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Anharmonic effects in an atomic monolayer thin crystal with honeycomb lattice structure are investigated by analytical and numerical lattice dynamical methods. Starting from a semiempirical model for anharmonic couplings of third and fourth orders, we study the in-plane and out-of-plane (flexural) mode components of the generalized wave vector dependent Gruneisen parameters, the thermal tension and the thermal expansion coefficients as a function of temperature and crystal size. From the resonances of the displacement-displacement correlation functions, we obtain the renormalization and decay rate of in-plane and flexural phonons as a function of temperature, wave vector, and crystal size in the classical and in the quantum regime. Quantitative results are presented for graphene. There, we find that the transition temperature T-alpha from negative to positive thermal expansion is lowered with smaller system size. Renormalization of the flexural mode has the opposite effect and leads to values of T-alpha approximate to 300 K for systems of macroscopic size. Extensive numerical analysis throughout the Brillouin zone explores various decay and scattering channels. The relative importance of normal and umklapp processes is investigated. The work is complementary to crystalline membrane theory and computational studies of anharmonic effects in two-dimensional crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000353031000001 Publication Date 2015-04-17
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 38 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 EuroGRAPHENE project CONGRAN. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number UA @ lucian @ c:irua:132512 Serial 4263
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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 (down) 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 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 Michel, K.H.; Verberck, B.
Title Phonon dispersions and piezoelectricity in bulk and multilayers of hexagonal boron nitride Type A1 Journal article
Year 2011 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 83 Issue 11 Pages (down) 115328-115328,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A unified theory of phonon dispersions and piezoelectricity in bulk and multilayers of hexagonal boron nitride (h-BN) is derived. The dynamical matrix is calculated on the basis of an empirical force constant model of intralayer valence and interlayer van der Waals interactions. Coulomb interactions are calculated by Ewalds method, adapted for the three-dimensional (3D) and the multilayer case. The deformation of the ionic charge distribution with long-wave lattice displacements is taken into account. Special attention is devoted to the nonanalytic long-range Coulomb contribution to the dynamical matrix which is different for the 3D crystal and the multilayer case. Consequently there is a splitting of the transverse optical (TO) and longitudinal optical (LO) phonon branches of E1u symmetry and a discontinuity of the A2u branch at the Γ point in 3D h-BN. No such splitting and discontinuity at Γ are present in multilayer crystals with a finite number N of layers. There a diverging bundle of N overbending optical phonon branches emerges from Γ. Borns long-wave theory is applied and extended for the study of piezoelectricity in layered crystals. While 3D h-BN and h-BN multilayers with an even number of layers (symmetry D6h) are not piezoelectric, multilayers with an uneven number of Nu layers (symmetry D3h) are piezoelectric; the piezoelectric coefficient e1,11 is inversely proportional to Nu.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000288783700005 Publication Date 2011-03-24
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 82 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-V1) and the Bijzonder Onderzoeksfonds, Universiteit Antwerpen (BOF-UA). ; Approved Most recent IF: 3.836; 2011 IF: 3.691
Call Number UA @ lucian @ c:irua:89602 Serial 2603
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Author Michel, K.H.; Verberck, B.
Title Theory of rigid-plane phonon modes in layered crystals Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 85 Issue 9 Pages (down) 094303-094303,11
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The lattice dynamics of low-frequency rigid-plane modes in metallic (graphene multilayers, GML) and in insulating (hexagonal boron-nitride multilayers, BNML) layered crystals is investigated. The frequencies of shearing and compression (stretching) modes depend on the layer number N and are presented in the form of fan diagrams. The results for GML and BNML are very similar. In both cases, only the interactions (van der Waals and Coulomb) between nearest-neighbor planes are effective, while the interactions between more distant planes are screened. A comparison with recent Raman scattering results on low-frequency shear modes in GML [Tan et al., Nat. Mater., in press, doi: 10.1038/nmat3245, (2012)] is made. Relations with the low-lying rigid-plane phonon dispersions in the bulk materials are established. Master curves, which connect the fan diagram frequencies for any given N, are derived. Static and dynamic thermal correlation functions for rigid-layer shear and compression modes are calculated. The results might be of use for the interpretation of friction force experiments on multilayer crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000301646000006 Publication Date 2012-03-19
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 38 Open Access
Notes ; The authors are indebted to J. Maultzsch for bringing Ref. 20 to their attention. They thank D. Lamoen, F.M. Peeters, B. Trauzettel, and C. Van Haesendonck for useful discussions. This work has been financially supported by the Research Foundation Flanders (FWO). ; Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:97787 Serial 3619
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Author Michel, K.H.; Scuracchio, P.; Peeters, F.M.
Title Sound waves and flexural mode dynamics in two-dimensional crystals Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 96 Issue 9 Pages (down) 094302
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from a Hamiltonian with anharmonic coupling between in-plane acoustic displacements and outof-plane (flexural) modes, we derived coupled equations of motion for in-plane displacements correlations and flexural mode density fluctuations. Linear response theory and time-dependent thermal Green's functions techniques are applied in order to obtain different response functions. As external perturbations we allow for stresses and thermal heat sources. The displacement correlations are described by a Dyson equation where the flexural density distribution enters as an additional perturbation. The flexural density distribution satisfies a kinetic equation where the in-plane lattice displacements act as a perturbation. In the hydrodynamic limit this system of coupled equations is at the basis of a unified description of elastic and thermal phenomena, such as isothermal versus adiabatic sound motion and thermal conductivity versus second sound. The general theory is formulated in view of application to graphene, two-dimensional h-BN, and 2H-transition metal dichalcogenides and oxides.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000409246200003 Publication Date 2017-09-05
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 6 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program. ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:145630 Serial 4751
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Author Michel, K.H.; Verberck, B.
Title Theory of the evolution of phonon spectra and elastic constants from graphene to graphite Type A1 Journal article
Year 2008 Publication Physical review : B : solid state Abbreviated Journal Phys Rev B
Volume 78 Issue 8 Pages (down) 085424,1-085424,17
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a unified theory of the phonon dispersions and elastic properties of graphene, graphite, and graphene multilayer systems. Starting from a fifth-nearest-neighbor force-constant model derived from full in-plane phonon dispersions of graphite [Mohr et al., Phys. Rev. B 76, 035439 (2007)], we use Born's long-wave method to calculate the tension and bending coefficients of graphene. Extending the model by interplanar interactions, we study the phonon dispersions and the elastic constants of graphite, and the phonon spectra of graphene multilayers. We find that the inner displacement terms due to sublattice shifts between inequivalent C atoms are quantitatively important in determining the elastomechanical properties of graphene and of graphite. The overall agreement between theory and experiment is very satisfactory. We investigate the evolution from graphene to graphite by studying the increase in the rigid plane optical mode as a function of the number of layers N. At N=10 the graphite value B2g1127 cm−1 is attained within a few percent.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000259406900106 Publication Date 2008-08-21
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 72 Open Access
Notes Approved Most recent IF: 3.836; 2008 IF: 3.322
Call Number UA @ lucian @ c:irua:76527 Serial 3622
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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 (down) 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 UA @ lucian @ c:irua:102740 Serial 3377
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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 (down) 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 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 (down) 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 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 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 (down) 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 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 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 (down) 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 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 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 (down) 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 20 Open Access
Notes Approved PHYSICS, APPLIED 28/145 Q1 #
Call Number UA @ lucian @ c:irua:104421 Serial 2031
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Author Neek-Amal, M.; Beheshtian, J.; Sadeghi, A.; Michel, K.H.; Peeters, F.M.
Title Boron nitride mono layer : a strain-tunable nanosensor Type A1 Journal article
Year 2013 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 117 Issue 25 Pages (down) 13261-13267
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The influence of triaxial in-plane strain on the electronic properties of a hexagonal boron-nitride sheet is investigated using density functional theory. Different from graphene, the triaxial strain localizes the molecular orbitals of the boron-nitride flake in its center depending on the direction of the applied strain. The proposed technique for localizing the molecular orbitals that are close to the Fermi level in the center of boron nitride flakes can be used to actualize engineered nanosensors, for instance, to selectively detect gas molecules. We show that the central part of the strained flake adsorbs polar molecules more strongly as compared with an unstrained sheet.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000321236400041 Publication Date 2013-06-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 38 Open Access
Notes ; This work was supported by the EU-Marie Curie IIF postdoc Fellowship/299855 (for M.N.-A.), the ESF EuroGRAPHENE project CONGRAN, the Flemish Science Foundation (FWO-VI), and the Methusalem Funding of the Flemish government. AS. would like to thank the Universiteit Antwerpen for its hospitality. ; Approved Most recent IF: 4.536; 2013 IF: 4.835
Call Number UA @ lucian @ c:irua:109829 Serial 249
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Author Nikolaev, A.V.; Michel, K.H.
Title Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solid C70 Type A1 Journal article
Year 1996 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 54 Issue 18 Pages (down) 12733-12743
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from a model of microscopic interactions between C-70 molecules, we have developed a theory which describes the orientational dynamics and its coupling to lattice displacements in the rhombohedral phase of C-70 fullerite. The Landau free energy is calculated. We obtain a first-order phase transition to a monoclinic structure with the space group P2(1)/m. The transition is driven by the condensation of orientational quadrupoles at the F point of the Brillouin zone of the rhombohedral lattice. We find no evidence that the monoclinic structure is connected with the freezing in of orientations around the fivefold molecular axis. We calculate the lattice strains that are associated with the transition to the monoclinic structure. The theory is compared with a range of experimental data on the phase transition.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1996VT68200028 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 5 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:16357 Serial 2034
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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 (down) 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 UA @ lucian @ c:irua:103350 Serial 578
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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 (down) 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 20 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:2973 Serial 2185
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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 (down) 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 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 Zieliński, P.; Michel, K.H.
Title Microscopic model of surfaces in orientationally disordered ionic crystals : the (001) surface of KCN Type A1 Journal article
Year 1992 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 46 Issue 8 Pages (down) 4806-4815
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The crystallographic structure and the distribution of orientations of molecular ions are studied near the surface in an orientationally disordered crystal with the use of a Green-function formalism. The orientational degrees of freedom are treated by means of symmetry-adapted functions of angular coordinates. The structure of the (001) surface of KCN in its cubic fcc phase is then predicted using the existing data on the interaction of the ions K+ and CN-. A local antiferroelectric and antiferroelastic order i shown to exist in the surface region. The magnitude of the order and the spatial extent of the ordered re ion increase as the temperature approaches the point of the phase transition to the ordered phase. The,influence of the external electric field on the structure of the surface is predicted.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1992JK72500049 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 4 Open Access
Notes Approved PHYSICS, CONDENSED MATTER 16/67 Q1 #
Call Number UA @ lucian @ c:irua:2974 Serial 2029
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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 (down) 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 33 Open Access
Notes Approved no
Call Number UA @ lucian @ c:irua:939 Serial 773
Permanent link to this record
 
 
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 (down) 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 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 (down) 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 UA @ lucian @ c:irua:102972 Serial 2298
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Author Verberck, B.; Michel, K.H.
Title Anisotropic packing of C-70 molecules in carbon nanotubes Type A1 Journal article
Year 2007 Publication Physica status solidi B-basic solid state physics Abbreviated Journal Phys Status Solidi B
Volume 244 Issue 11 Pages (down) 4279-4282
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000251355800092 Publication Date 2007-10-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972;1521-3951; ISBN Additional Links UA library record; WoS full record
Impact Factor 1.674 Times cited Open Access
Notes Approved Most recent IF: 1.674; 2007 IF: 1.071
Call Number UA @ lucian @ c:irua:67350 Serial 128
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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 (down) 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 UA @ lucian @ c:irua:102920 Serial 3589
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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 (down) 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 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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