Original scientific paper

Renormalization Group for the Linear-Chain Heisenberg Model

Thomas G. Schmalz ; Theoretical Chemical Physics Group, Department of Marine Sciences, Texas A&M University at Galveston, Galveston, Texas 77553-1675
Douglas J. Klein ; Theoretical Chemical Physics Group, Department of Marine Sciences, Texas A&M University at Galveston, Galveston, Texas 77553-1675

Abstract

Several real-space renormalization group techniques are applied to the spin-1/2 linear-chain Heisenberg model. The particular schemes investigated renormalize blocks (or subchains) to new spin-1/2 sites, each coupled only to nearest neighbor (like-renormalized) sites. Iteration of the renormalization transformation eventually provides values for the per-site properties of an infinite chain. A first-order perturbational method, a related variationally optimized approach, and a cluster-expansion technique are applied using blocks of several different sizes. The first two of these schemes are found to give less accurate values and converge more slowly with block size than the cluster-expansion technique, though this last technique (unlike the first two) is not variationally bounded. A novel modification of the perturbation-variation scheme, where one renormalizes at each iteration only a single block at the end of the chain, is also noted as a possibility and is found to give variationally bounded results comparable to the cluster expansion.

Keywords

Hrčak ID:

137105

URI

https://hrcak.srce.hr/137105

Publication date:

1.6.1993.

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