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Records |
Links |
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Author |
Mattauch, S.; Heger, G.; Michel, K.H. |
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Title |
High resolution neutron and X-ray diffraction studies as a function of temperature and electric field of the ferroelectric phase transition of RDP |
Type |
A1 Journal article |
| |
Year |
2004 |
Publication  |
Crystal research and technology |
Abbreviated Journal |
Cryst Res Technol |
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Volume |
39 |
Issue |
12 |
Pages |
1027-1054 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Neutron and high resolution X-ray diffraction investigations on perfect single crystals of RbH2PO4 (RDP), a hydrogen bonded ferroelectric of KDP type are reported. The results of crystal structure analysis from diffraction data, below and above the paraelectric – ferroelectric phase transition, support a disorder – order character Of [PO4H2](-)-groups. The tetragonal symmetry of the paraelectric phase with the double well potential of the hydrogen atoms obtained by diffraction, results simply from a time-space average of orthorhombic symmetry. According to the group – subgroup relation between the tetragonal space group 142d and the orthorhombic Fdd2 a short range order of ferroelectric clusters in the tetragonal phase is observed. With decreasing temperature the ferroelectric clusters increase and the long range interaction between their local polarisation vectors leads to the formation of lamellar ferroelectric domains with alternating polarisation directions at T-C = 147 K. From the high resolution X-ray data it is concluded that below T-C the ferroelastic strain in the (a,b)-plane leads to micro-angle grain boundaries at the domain walls. The tilt angle is enhanced by an applied electric field parallel to the ferroelectric axis. The resulting dislocations at the domain walls persist in the paraelectric phase leading to a memory effect for the arrangement of twin lamellae. With increased electric field the phase transition temperature T-C is decreased. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000225681100001 |
Publication Date |
2004-11-12 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0232-1300;1521-4079; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1 |
Times cited |
12 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1; 2004 IF: 0.770 |
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Call Number |
UA @ lucian @ c:irua:94785 |
Serial |
1459 |
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Author |
Nikolaev, A.V.; Michel, K.H. |
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Title |
Many electron- and hole terms of molecular ions C60n\pm |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Coupling In Chemistry And Physics |
Abbreviated Journal |
Adv Quantum Chem |
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Volume |
44 |
Issue |
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Pages |
305-312 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000188940800019 |
Publication Date |
2004-05-19 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0065-3276; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.196 |
Times cited |
1 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.196; 2003 IF: 0.375 |
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Call Number |
UA @ lucian @ c:irua:104131 |
Serial |
1942 |
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Author |
Michel, K.H. |
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Title |
Sequence of orientational phase transitions in solid C60 |
Type |
A1 Journal article |
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Year |
1992 |
Publication |
Chemical physics letters |
Abbreviated Journal |
Chem Phys Lett |
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Volume |
193 |
Issue |
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Pages |
478-480 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
A1992HZ32900006 |
Publication Date |
2002-07-25 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0009-2614; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.897 |
Times cited |
14 |
Open Access |
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Notes |
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Approved |
MATERIALS SCIENCE, MULTIDISCIPLINARY 96/271 Q2 # |
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Call Number |
UA @ lucian @ c:irua:2971 |
Serial |
2985 |
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Author |
Michel, K.H.; Verberck, B.; Nikolaev, A. |
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Title |
Mercator maps of orientations of a C60 molecule in single-walled nanotubes with distinct radii |
Type |
A1 Journal article |
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Year |
2005 |
Publication |
AIP conference proceedings |
Abbreviated Journal |
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Volume |
786 |
Issue |
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Pages |
69-72 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Thesis |
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Publisher |
Amer inst physics |
Place of Publication |
Melville |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0094-243x |
ISBN |
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Additional Links |
UA library record; WoS full record; |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:94738 |
Serial |
1993 |
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Author |
Verberck, B.; Nikolaev, A.V.; Michel, K.H. |
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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 |
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Volume |
723 |
Issue |
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Pages |
339-342 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0094-243x |
ISBN |
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Additional Links |
UA library record; WoS full record; |
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Impact Factor |
|
Times cited |
|
Open Access |
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| |
Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:94831 |
Serial |
2513 |
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| Permanent link to this record |
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Author |
Bussmann-Holder, A.; Michel, K.H. |
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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 |
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Volume |
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Issue |
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Pages |
202-206 |
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Keywords |
P1 Proceeding; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York |
Editor |
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Language |
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Wos |
000075034000022 |
Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
436 |
Edition |
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ISSN |
1-56396-730-8 |
ISBN |
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Additional Links |
UA library record; WoS full record; |
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Impact Factor |
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Times cited |
|
Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:104344 |
Serial |
2733 |
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| Permanent link to this record |
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Author |
Nikolaev, A.V.; Michel, K.H. |
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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 |
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Volume |
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Issue |
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Pages |
393-396 |
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Keywords |
P1 Proceeding; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York |
Editor |
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Language |
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Wos |
000224699400085 |
Publication Date |
2004-11-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
723 |
Series Issue |
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Edition |
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ISSN |
0-7354-0204-3 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
Times cited |
|
Open Access |
|
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| |
Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:103752 |
Serial |
27 |
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| Permanent link to this record |
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Author |
Nikolaev, A.V.; Michel, K.H. |
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Title |
Molecular terms and optical transitions of C60n+/- molecular ions |
Type |
P1 Proceeding |
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Year |
2002 |
Publication |
AIP conference proceedings
T2 – 16th International Winterschool on Electronic Properties of Novel, Materials, MAR 02-09, 2002, KIRCHBERG, AUSTRIA |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
417-420 |
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Keywords |
P1 Proceeding; Condensed Matter Theory (CMT) |
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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. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
633 |
Series Issue |
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Edition |
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ISSN |
0-7354-0088-1 |
ISBN |
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Additional Links |
UA library record; WoS full record; |
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Impact Factor |
|
Times cited |
|
Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:103905 |
Serial |
2187 |
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| Permanent link to this record |
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Author |
Michel, K.H.; Lamoen, D.; David, W.I.F. |
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Title |
Orientational order and disorder in solid C60 : theory and diffraction experiments |
Type |
A1 Journal article |
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Year |
1995 |
Publication |
Acta crystallographica: section A: foundations of crystallography |
Abbreviated Journal |
Acta Crystallogr A |
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Volume |
51 |
Issue |
3 |
Pages |
365-374 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Copenhagen |
Editor |
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Language |
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Wos |
A1995RB59400018 |
Publication Date |
2002-07-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0108-7673; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.307 |
Times cited |
14 |
Open Access |
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Notes |
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Approved |
CHEMISTRY, MULTIDISCIPLINARY 65/163 Q2 # CRYSTALLOGRAPHY 10/26 Q2 # |
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Call Number |
UA @ lucian @ c:irua:12189 |
Serial |
2518 |
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| Permanent link to this record |
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Author |
Lamoen, D.; Michel, K.H. |
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Title |
Molecular structure, crystal field and orientational order in solid C60 |
Type |
H1 Book chapter |
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Year |
1994 |
Publication |
|
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
183-202 |
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Keywords |
H1 Book chapter; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
s.l. |
Editor |
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Language |
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Wos |
A1994BE86T00011 |
Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
0-7923-3109-5 |
Additional Links |
UA library record; WoS full record; |
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Impact Factor |
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Times cited |
|
Open Access |
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Notes |
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Approved |
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Call Number |
UA @ lucian @ c:irua:9355 |
Serial |
2186 |
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| Permanent link to this record |
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Author |
Michel, K.H.; Copley, J.R.D. |
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Title |
Orientation fluctuations, diffuse scattering and orientational order in solid C60 |
Type |
H3 Book chapter |
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Year |
1996 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
381-384 |
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Keywords |
H3 Book chapter; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
World Scientific |
Place of Publication |
Singapore |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
COMPUTER SCIENCE, INTERDISCIPLINARY 11/104 Q1 # PHYSICS, MATHEMATICAL 1/53 Q1 # |
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Call Number |
UA @ lucian @ c:irua:16358 |
Serial |
2512 |
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| Permanent link to this record |
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Author |
Nikolaev, A.V.; Michel, K.H.; Copley, J.R.D. |
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Title |
Orientational disorder and order in C60-fullerite and in MC60-alkali metal fullerides |
Type |
H3 Book chapter |
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Year |
1999 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
183-214 |
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Keywords |
H3 Book chapter; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
Plenum Press |
Place of Publication |
New York |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ lucian @ c:irua:28505 |
Serial |
2515 |
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| Permanent link to this record |
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Author |
Michel, K.H.; Nikolaev, A.V.; Verberck, B. |
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Title |
Theory of crystal structures of polymerized C60-fullerite and fullerides AC60, A=K, Rb, Cs |
Type |
H1 Book chapter |
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Year |
2001 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
H1 Book chapter; Condensed Matter Theory (CMT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
s.l. |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
462-465 |
Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record; |
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| |
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 |
