Energy of bond defects in quantum spin chains obtained from local approximations and from exact diagonalization

We study the influence of ferromagnetic and antiferromagnetic bond defects on the ground-state energy of antiferromagnetic spin chains. In the absence of translational invariance, the energy spectrum of the full Hamiltonian is obtained numerically, by an iterative modification of the power algorithm...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2008-07, Vol.320 (14), p.e421-e424
Main Authors: Líbero, V.L., Capelle, K., Souza, F.C., Fávaro, A.P.
Format: Article
Language:English
Subjects:
Bond defects
Correlation energy
Density-functional theory
Heisenberg model
Magnetic impurities
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Summary:We study the influence of ferromagnetic and antiferromagnetic bond defects on the ground-state energy of antiferromagnetic spin chains. In the absence of translational invariance, the energy spectrum of the full Hamiltonian is obtained numerically, by an iterative modification of the power algorithm. In parallel, approximate analytical energies are obtained from a local-bond approximation, proposed here. This approximation results in significant improvement upon the mean-field approximation, at negligible extra computational effort.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2008.02.187