paper

Variational Hilbert space truncation approach to quantum Heisenberg antiferromagnets on frustrated clusters

arXiv:cond-mat/9507060 · doi:10.1103/PhysRevB.53.2546

Abstract

We study the spin- Heisenberg antiferromagnet on a series of finite-size clusters with features inspired by the fullerenes. Frustration due to the presence of pentagonal rings makes such structures challenging in the context of quantum Monte-Carlo methods. We use an exact diagonalization approach combined with a truncation method in which only the most important basis states of the Hilbert space are retained. We describe an efficient variational method for finding an optimal truncation of a given size which minimizes the error in the ground state energy. Ground state energies and spin-spin correlations are obtained for clusters with up to thirty-two sites without the need to restrict the symmetry of the structures. The results are compared to full-space calculations and to unfrustrated structures based on the honeycomb lattice.

22 pages and 12 Postscript figures

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