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	Author	Nikolaev, A.V.; Michel, K.H.
	Title	Molecular terms and optical transitions of C₆₀^n+/- molecular ions			Type	P1 Proceeding
	Year	2002	Publication	AIP conference proceedings T2 – 16th International Winterschool on Electronic Properties of Novel, Materials, MAR 02-09, 2002, KIRCHBERG, AUSTRIA	Abbreviated Journal
	Volume		Issue		Pages	417-420
	Keywords	P1 Proceeding; Condensed Matter Theory (CMT)
	Abstract	We have studied the molecular energy terms of the hole configurations (h(u)(+))(m), m=2,3,4,5 of C-60(m+) cations and the electronic configurations (t(1u))(n) n=2,3,4, as well as (t(1u))(n-1)t(1g) of the C-60(n-) anions. The lowest terms (within an energy span of 0.03 eV) for C-60(2+) are three triplets T-3(1g), (3)G(g), T-3(2g) and for C-60(3+) are three quartets T-4(1u), (4)G(u), T-4(2u), which favor Jahn-Teller distortions. For the ground state of C-60(2-) we find a triplet T-3(1g) in agreement with Hund's rules. Our method takes into account intramolecular direct and exchange multipolar Coulomb interactions.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume	633	Series Issue		Edition
	ISSN	0-7354-0088-1	ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:103905			Serial	2187
Permanent link to this record



	Author	Bussmann-Holder, A.; Michel, K.H.
	Title	Proton tunneling and nonlinear polarizability effects in hydrogen-bonded ferroelectrics			Type	P1 Proceeding
	Year	1998	Publication	AIP conference proceedings T2 – 5th Williamsburg Workshop on 1st-Principles Calculations for, Ferroelectrics, FEB 01-04, 1998, WILLIAMSBURG, VA	Abbreviated Journal
	Volume		Issue		Pages	202-206
	Keywords	P1 Proceeding; Condensed Matter Theory (CMT)
	Abstract	Hydrogen-bonded ferroelectrics are modelled by a coupled spin/nonlinear lattice (polarizability) interaction Hamiltonian, where specifically the geometry of the hydrogen bond is included. The model leads to a structural phase transition and describes correctly the isotope effect due to the substitution H/D in hydrogen-bonded systems in terms of bond length changes.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York	Editor
	Language		Wos	000075034000022	Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue	436	Edition
	ISSN	1-56396-730-8	ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:104344			Serial	2733
Permanent link to this record



	Author	Michel, K.H.; Copley, J.R.D.
	Title	Orientation fluctuations, diffuse scattering and orientational order in solid C₆₀			Type	H3 Book chapter
	Year	1996	Publication		Abbreviated Journal
	Volume		Issue		Pages	381-384
	Keywords	H3 Book chapter; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	World Scientific	Place of Publication	Singapore	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record
	Impact Factor		Times cited		Open Access
	Notes				Approved	COMPUTER SCIENCE, INTERDISCIPLINARY 11/104 Q1 # PHYSICS, MATHEMATICAL 1/53 Q1 #
	Call Number	UA @ lucian @ c:irua:16358			Serial	2512
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	21	Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:21181			Serial	2517
Permanent link to this record



	Author	Nikolaev, A.V.; Prassides, K.; Michel, K.H.
	Title	Phase transitions in AC₆₀ (A=Rb, Cs) fullerides			Type	A3 Journal article
	Year	1997	Publication	Recent advances in the chemistry and physics of fullerenes and related materials	Abbreviated Journal
	Volume	5	Issue		Pages	450-460
	Keywords	A3 Journal article; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:21182			Serial	2596
Permanent link to this record



	Author	Nikolaev, A.V.; Michel, K.H.; Copley, J.R.D.
	Title	Orientational disorder and order in C60-fullerite and in MC₆₀-alkali metal fullerides			Type	H3 Book chapter
	Year	1999	Publication		Abbreviated Journal
	Volume		Issue		Pages	183-214
	Keywords	H3 Book chapter; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	Plenum Press	Place of Publication	New York	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:28505			Serial	2515
Permanent link to this record



	Author	Michel, K.H.; Nikolaev, A.V.; Verberck, B.
	Title	Theory of crystal structures of polymerized C₆₀-fullerite and fullerides AC₆₀, A=K, Rb, Cs			Type	H1 Book chapter
	Year	2001	Publication		Abbreviated Journal
	Volume		Issue		Pages
	Keywords	H1 Book chapter; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	s.l.	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume	462-465	Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:36883			Serial	3614
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	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	Lamoen, D.; Michel, K.H.
	Title	Molecular structure, crystal field and orientational order in solid C₆₀			Type	H1 Book chapter
	Year	1994	Publication		Abbreviated Journal
	Volume		Issue		Pages	183-202
	Keywords	H1 Book chapter; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	s.l.	Editor
	Language		Wos	A1994BE86T00011	Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN	0-7923-3109-5	Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved
	Call Number	UA @ lucian @ c:irua:9355			Serial	2186
Permanent link to this record



	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	33	Open Access
	Notes				Approved	no
	Call Number	UA @ lucian @ c:irua:939			Serial	773
Permanent link to this record



	Author	Michel, K.H.; Verberck, B.; Nikolaev, A.
	Title	Mercator maps of orientations of a C₆₀ molecule in single-walled nanotubes with distinct radii			Type	A1 Journal article
	Year	2005	Publication	AIP conference proceedings	Abbreviated Journal
	Volume	786	Issue		Pages	69-72
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	We study the confinement of a C-60 molecule encapsulated in a cylindrical nanotube as a function of the tube radius. Drawing the Mercator maps of the potential, we find two distinct molecular orientations; for tubes with small radii, R-T less than or similar to 7 angstrom, a fivefold axis of the molecule coincides with the tube long axis, for larger radii, R-T less than or similar to 8 angstrom, a threefold axis of the molecule coincides with the tube long axis. These different orientations are caused by the relative importance of the repulsive and the attractive parts of the van der Waals potentials of the molecule with the tube wall for small and large tubes respectively. Experimental evidence is provided by the apparent splitting of A(g) modes of the C-60 molecule in resonant Raman scattering.
	Address
	Corporate Author				Thesis
	Publisher	Amer inst physics	Place of Publication	Melville	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0094-243x	ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:94738			Serial	1993
Permanent link to this record



	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	2004	Publication	AIP conference proceedings	Abbreviated Journal
	Volume	723	Issue		Pages	339-342
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Polymerized KC60 undergoes a structural phase transition accompanied by a metal-insulator transition around 50 K. To explain the structural aspect, a mechanism involving small orientational deviations of the valence electron density on every C-60 monomer orientational charge density waves (OCDWs) – has already been proposed earlier. In the present work, we address the metal-insulator transition using the OCDW concept. We are inspired by the analogy between a polymer chain exhibiting an OCDW and a linear atomic chain undergoing a static lattice deformation doubling the unit cell: such a deformation implies a band gap at the zone boundary, yielding an insulating state (Peierls instability). Within our view, a similar mechanism occurs in polymerized KC60; the OCDW plays the role of the lattice deformation. We present tight-binding band structure calculations and conclude that the metal-insulator transition can indeed be explained using OCDWs, but that the threedimensionality of the crystal plays an unexpected key role.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York	Editor
	Language		Wos		Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0094-243x	ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:94831			Serial	2513
Permanent link to this record



	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	10	Open Access
	Notes				Approved	Most recent IF: 3.836; 2002 IF: NA
	Call Number	UA @ lucian @ c:irua:94907			Serial	3608
Permanent link to this record



	Author	Verberck, B.; Heresanu, V.; Rouziere, S.; Cambedouzou, J.; Launois, P.; Kovats, E.; Pekker, S.; Vliegenthart, G.A.; Michel, K.H.; Gompper, G.
	Title	Fullerene-cubane : X-ray scattering experiments and Monte Carlo simulations			Type	A1 Journal article
	Year	2008	Publication	Fullerenes, nanotubes, and carbon nanostructures T2 – 8th Biennial International Workshop on Fullerenes and Atomic Clusters, (IWFAC 2007), JUL 02-06, 2007, St Petersburg, RUSSIA	Abbreviated Journal	Fuller Nanotub Car N
	Volume	16	Issue	5-6	Pages	293-300
	Keywords	A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
	Abstract	We report single-crystal X-ray diffuse scattering measurements on C-60.C8H8 fullerene-cubane showing that the C-60 molecules are orientationally disordered at 300 and 150K and get ordered at low temperatures. Monte Carlo simulations provide further insight in the orientational behavior of both C-60 and C8H8 molecules; low-temperature molecular orientations are predicted.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000259645200003	Publication Date	2008-09-28
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1536-383X;1536-4046;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.35	Times cited	6	Open Access
	Notes				Approved	Most recent IF: 1.35; 2008 IF: 0.680
	Call Number	UA @ lucian @ c:irua:102640			Serial	1295
Permanent link to this record



	Author	Nikolaev, A.V.; Michel, K.H.
	Title	Superexchange and electron correlations in alkali fullerides AC₆₀, A=K, Rb, Cs			Type	A1 Journal article
	Year	2005	Publication	The journal of chemical physics	Abbreviated Journal	J Chem Phys
	Volume	122	Issue	6	Pages	064310-64314
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Superexchange interactions in alkali fullerides AC(60) are derived for C-60 molecular ions separated by interstitial alkali-metal ions. We use a multiconfiguration approach which comprises the lowest molecular orbital states of the C-60 molecule and the excited s and d states of the alkali-metal atom A. Interactions are described by the valence bond (Heitler-London) method for a complex (C-60 – A – C-60) – with two valence electrons. The electronic charge transfer between the alkali-metal atom and a neighboring C-60 molecule is not complete. The occupation probability of excited d and s states of the alkali atom is not negligible. In correspondence with the relative positions of the C-60 molecules and A atoms in the polymer crystal, we consider 180degrees and 90degrees (angle) superexchange pathways. For the former case the ground state is found to be a spin singlet separated from a triplet at similar to20 K. For T < 20 K there appear strong spin correlations for the 180degrees superexchange pathway. The results are related to spin lattice relaxation experiments on CsC60 in the polymerized and in the quenched cubic phase. (C) 2005 American Institute of Physics.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000226918100018	Publication Date	2005-02-02
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-9606;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.965	Times cited	11	Open Access
	Notes				Approved	Most recent IF: 2.965; 2005 IF: 3.138
	Call Number	UA @ lucian @ c:irua:102740			Serial	3377
Permanent link to this record



	Author	Bussmann-Holder, A.; Michel, K.H.
	Title	The isotope effect in hydrogen-bonded systems			Type	A1 Journal article
	Year	1998	Publication	International journal of modern physics: B: condensed matter physics, statistical physics, applied physics T2 – 1st International Conference on New Theories, Discoveries, and, Applications of Superconductors and Related Materials (New3SC-1), FEB 19-24, 19	Abbreviated Journal	Int J Mod Phys B
	Volume	12	Issue	29-31	Pages	3406-3408
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The giant isotope effect on the ferro- and antiferroelectric transition temperature upon deuteration of hydrogen-bonded systems is well known experimentally since various decades. Yet, theoretically only recently a microscopic understanding of this effect has been achieved which, specifically, took into account the geometry of the O ... H ... O bond. The implications of this modeling are multiple as numerous hydrogen-bonded organic systems show the same effects as ferro- and antiferroelectrics, i.e., cooperative proton tunneling at a well-defined temperature.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Singapore	Editor
	Language		Wos	000079114500104	Publication Date	2003-10-01
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0217-9792;1793-6578;	ISBN		Additional Links	UA library record; WoS full record
	Impact Factor	0.736	Times cited		Open Access
	Notes				Approved	Most recent IF: 0.736; 1998 IF: 0.987
	Call Number	UA @ lucian @ c:irua:102920			Serial	3589
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	26	Pages	4353-4370
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Differential cross sections for neutron and x-ray scattering have been derived for the orientationally disordered phase of solid C60. Interaction centres are placed at nuclei and at the centres of interatomic bonds. Bragg and diffuse scattering cross sections, for single crystals and for powders, are formulated using symmetry-adapted rotator functions. Thermal averages are calculated taking account of crystal field effects. Thermally averaged orientational distribution functions have also been calculated.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	A1993LK74100008	Publication Date	2002-08-25
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0953-8984;1361-648X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.346	Times cited	34	Open Access
	Notes				Approved	MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 #
	Call Number	UA @ lucian @ c:irua:102972			Serial	2298
Permanent link to this record



	Author	Verberck, B.; Nikolaev, A.V.; Michel, K.H.
	Title	Theoretical model for the structural phase transition and the metal-insulator transition in polymerized KC₆₀			Type	A1 Journal article
	Year	2004	Publication	Fullerenes, nanotubes, and carbon nanostructures T2 – 6th Biennial International Workshop on Fullerenes and Atomic Clusters, JUN 30-JUL 04, 2003, St Petersburg, RUSSIA	Abbreviated Journal	Fuller Nanotub Car N
	Volume	12	Issue	1-2	Pages	243-252
	Keywords	A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
	Abstract	The recently discovered structural phase transition in Polymerized KC60 at about 50K leads to a doubling of the unit cell volume and is accompanied by a metal-insulator transition. Here, we show that the ((a) over right arrow + (c) over right arrow, (b) over right arrow, (a) over right arrow – (c) over right arrow) superstructure results from orientational charge density waves along the polymer chains and correlated displacements of the K+ ions. The presented model can also account for the metal-insulator transition. The effect is specific for the space group Pmnn of KC60 and is absent in both Rb- and CsC60 (space group 12/m), in agreement with the present experimental knowledge of these compounds.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000220551600040	Publication Date	2004-03-15
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1536-383X;1536-4046;	ISBN		Additional Links	UA library record; WoS full record
	Impact Factor	1.35	Times cited		Open Access
	Notes				Approved	Most recent IF: 1.35; 2004 IF: 1.117
	Call Number	UA @ lucian @ c:irua:103259			Serial	3607
Permanent link to this record



	Author	Verberck, B.; Michel, K.H.; Nikolaev, A.V.
	Title	Crystal structures of polymerized fullerides AC₆₀, A=K, Rb, Cs, and alkali-mediated interactions			Type	A1 Journal article
	Year	2002	Publication	The journal of chemical physics	Abbreviated Journal	J Chem Phys
	Volume	116	Issue	23	Pages	10462-10474
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Starting from a model of rigid interacting C-60 polymer chains on an orthorhombic lattice, we study the mutual orientation of the chains and the stability of the crystalline structures Pmnn and I2/m. We take into account (i) van der Waals interactions and electric quadrupole interactions between C-60 monomers on different chains as well as (ii) interactions of the monomers with the surrounding alkali atoms. The direct interactions (i) always lead to an antiferrorotational structure Pmnn with alternate orientation of the C-60 chains in planes (001). The interactions (ii) with the alkalis consist of two parts: translation-rotation (TR) coupling where the orientations of the chains interact with displacements of the alkalis, and quadrupolar electronic polarizability (ep) coupling, where the electric quadrupoles on the C-60 monomers interact with induced quadrupoles due to excited electronic d-states of the alkalis. Both interactions (ii) lead to an effective orientation-orientation interaction between the C-60 chains and always favor the ferrorotational structure I2/m, where C-60 chains have a same orientation. The structures Pmnn for KC60 and I2/m for Rb- and CsC60 are the result of a competition between the direct interaction (i) and the alkali-mediated interactions (ii). In Rb- and CsC60 the latter are found to be dominant, the preponderant role being played by the quadrupolar electronic polarizability of the alkali ions. (C) 2002 American Institute of Physics.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000175905800044	Publication Date	2002-07-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-9606;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.965	Times cited	12	Open Access
	Notes				Approved	Most recent IF: 2.965; 2002 IF: 2.998
	Call Number	UA @ lucian @ c:irua:103350			Serial	578
Permanent link to this record



	Author	Bussmann-Holder, A.; Dalal, N.; Michel, K.H.
	Title	Polarizability induced cooperative proton ordering, coexistence of order/disorder and displacive dynamics and isotope effects in hydrogen-bonded systems			Type	A1 Journal article
	Year	2000	Publication	The journal of physics and chemistry of solids T2 – Williamsburg Workshop on Ferroelectrics 99, JAN 31-FEB 03, 1999, WILLIAMSBURG, VIRGINIA	Abbreviated Journal	J Phys Chem Solids
	Volume	61	Issue	2	Pages	271-274
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Despite the general belief that hydrogen-bonded ferro- and antiferroelectrics undergo a pure order/disorder transition at the structural instability, new NMR data and a new theoretical concept yield convincing evidence that a pronounced displacive component is present in these systems, which modifies substantially the temperature dependencies of the tunnel and lattice mode frequencies. The experiments and their interpretation are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.
	Address
	Corporate Author				Thesis
	Publisher	Pergamon-elsevier science ltd	Place of Publication	Oxford	Editor
	Language		Wos	000084147000020	Publication Date	2002-07-25
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-3697;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.059	Times cited	8	Open Access
	Notes				Approved	Most recent IF: 2.059; 2000 IF: 1.003
	Call Number	UA @ lucian @ c:irua:103469			Serial	2660
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	Author	Nikolaev, A.V.; Michel, K.H.
	Title	Ab initio approach to superexchange interactions in alkali doped fullerides AC₆₀			Type	P1 Proceeding
	Year	2004	Publication	AIP conference proceedings T2 – 18th International Winterschool/Euroconference on Electronic Properties, of Novel Materials, MAR 06-JUN 13, 2004, Kirchberg, AUSTRIA	Abbreviated Journal
	Volume		Issue		Pages	393-396
	Keywords	P1 Proceeding; Condensed Matter Theory (CMT)
	Abstract	The superexchange interactions between the fullerenes arise as a result of the electron transfer from the C-60 molecule to the alkali atom and back. We present a scheme, which is a configuration interaction approach based on the valence bond (Heitler-London) method. The effect of superexchange is described together with chemical bonding by constructing and solving a secular equation, rather than by using a perturbation treatment. We have considered 180degrees and 90degrees superexchange for the C-60 Cs-C-60 pathways. The calculations account for unusual electronic properties of polymer orthorhombic and quenched cubic phases of CsC60: two lines in nuclear magnetic resonance experiments, the development of a spin-singlet ground state and a decrease of magnetic susceptibility as T-->0.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York	Editor
	Language		Wos	000224699400085	Publication Date	2004-11-11
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume	723	Series Issue		Edition
	ISSN	0-7354-0204-3	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:103752			Serial	27
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	Author	Verberck, B.; Nikolaev, A.V.; Michel, K.H.
	Title	Orientational charge density waves and the metal-insulator transition in polymerized KC₆₀			Type	A1 Journal article
	Year	2005	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	71	Issue	16	Pages	165117-11
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	A theoretical model is presented for the description of the metal-insulator transition which accompanies the structural phase transition at T approximate to 50 K in polymerized KC60. The model involves orientational charge density waves (along the C-60 polymer chains) which were introduced previously for a description of the structural phase transition. A satisfactory qualitative and quantitative understanding is obtained when the three-dimensionality of the crystal and the presence of the K+ counterions is properly taken into account.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000228763100035	Publication Date	2005-04-27
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	1	Open Access
	Notes				Approved	Most recent IF: 3.836; 2005 IF: 3.185
	Call Number	UA @ lucian @ c:irua:104076			Serial	2514
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	Author	Nikolaev, A.V.; Michel, K.H.
	Title	Many electron- and hole terms of molecular ions C₆₀^n\pm			Type	A1 Journal article
	Year	2003	Publication	Coupling In Chemistry And Physics	Abbreviated Journal	Adv Quantum Chem
	Volume	44	Issue		Pages	305-312
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000188940800019	Publication Date	2004-05-19
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0065-3276;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.196	Times cited	1	Open Access
	Notes				Approved	Most recent IF: 1.196; 2003 IF: 0.375
	Call Number	UA @ lucian @ c:irua:104131			Serial	1942
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	Author	Copley, J.R.D.; Michel, K.H.
	Title	Multiple orientational order parameters in solid C₆₀			Type	A1 Journal article
	Year	1997	Publication	Physica: B : condensed matter T2 – International Conference on Neutron Scattering, AUG 17-21, 1997, TORONTO, CANADA	Abbreviated Journal	Physica B
	Volume	241	Issue		Pages	454-455
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The transition Fm (3) over bar m -->Pa (3) over bar in solid C-60 is driven by the condensation of orientational modes belonging to X-5(+) irreducible representations (irreps) of Fm (3) over bar m. Taking into account irreps up to the manifold l = 12, we have studied the primary and secondary orientational order parameters loops). We have numerically solved the coupled molecular field equations for these oops and calculated the temperature dependence of Bragg reflection intensities. (C) 1998 Elsevier Science B.V. All rights reserved.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000074062600130	Publication Date	2002-07-25
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0921-4526;	ISBN		Additional Links	UA library record; WoS full record
	Impact Factor	1.386	Times cited		Open Access
	Notes				Approved	Most recent IF: 1.386; 1997 IF: 0.991
	Call Number	UA @ lucian @ c:irua:104360			Serial	2228
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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	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	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	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.
	Title	Rigid-plane phonons in layered crystals			Type	A1 Journal article
	Year	2012	Publication	Physica status solidi: B: basic research	Abbreviated Journal	Phys Status Solidi B
	Volume	249	Issue	12	Pages	2604-2607
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The determination of the layer number ${\cal N}$ in nanoscale thin layered crystals is a challenging problem of technological relevance. In addition to innovative experimental techniques, a thorough knowledge of the underlying lattice dynamics is required. Starting from phenomenological atomic interaction potentials we have carried out an analytical study of the low-frequency optical phonon dispersions in layered crystals. At the gamma point of the two-dimensional Brillouin zone the optical phonon frequencies correspond to rigid-plane shearing and compression modes. We have investigated graphene multilayers (GML) and hexagonal boron-nitride multilayers (BNML). The frequencies show a characteristic dependence on ${\cal N}$. The results which are represented in the form of fan diagrams are very similar for both materials. Due to charge neutrality within layers Coulomb forces play no role, only van der Waals forces between nearest neighbor layers are relevant. The theoretical results agree with recent low-frequency Raman results on rigid-layer modes [Tan et al., Nature Mater. 11, 294 (2012)] in GML and double-resonant Raman scattering data on rigid-layer compression modes [Herziger et al., Phys. Rev. B 85, 235447 (2012)] in GML. (C) 2012 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Berlin	Editor
	Language		Wos	000312215300072	Publication Date	2012-11-19
	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	1	Open Access
	Notes	; 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; 2012 IF: 1.489
	Call Number	UA @ lucian @ c:irua:105992			Serial	2907
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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	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	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	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.; 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	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
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