Publication
Title
Superexchange and electron correlations in alkali fullerides $AC_{60}$, A=K, Rb, Cs
Author
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.
Language
English
Source (journal)
The journal of chemical physics. - New York, N.Y.
Publication
New York, N.Y. : 2005
ISSN
0021-9606
Volume/pages
122 :6 (2005) , p. 1-14
Article Reference
064310
ISI
000226918100018
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
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