Electron-phonon interaction in carbon clathrate hex- $\mathsf{C_{40}}$ |
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Authors: | I?Spagnolatti Email author" target="_blank">M?BernasconiEmail author G?Benedek |
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Institution: | 1.Institut für Theoretische Physik, Heinrich-Heine-Universit?t, 40225 Düsseldorf, Germany,DE;2.Institute of Physics, Chinese Academy of Science, PO Box 603, Beijing 100080, PR China,CN |
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Abstract: | We investigate an extended spin ladder with diagonal frustrated exchanges in a wide parameter regime. By representing the
model as a sum of semidefinite positive projection operators, we prove that this model has exactly a dimer ground state. Smoothly
changing parameters may lead the model cover several exactly known models. Starting from this ladder model, we proposed two
two-dimensional net models with exact ground states. The quantum phase transition of the ground state, due to the change of
exchange strengths along perpendicular rungs, is also discussed.
Received 13 October 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: schen@thphy.uni.duesseldorf.de |
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Keywords: | PACS 75 10 Jm Quantized spin models |
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