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

Abstract

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.

3 pages, 2 figures. Manuscript accepted by Journal of Magnetism and Magnetic Materials, special issue for LAWMMM 2007 conference

References in corpus (3)

• Density-functionals not based on the electron gas: Local-density approximation for a Luttinger liquid
• Spin-density-functional theory: some open problems and application to inhomogeneous Heisenberg models
• Impurity and boundary effects in one and two-dimensional inhomogeneous Heisenberg antiferromagnets

Cited by in corpus (1)

• Artificial neural networks for density-functional optimizations in fermionic systems