Ravi Chandra, V. ; Sen, Diptiman ; Surendran, Naveen (2006) Gapless points of dimerized quantum spin chains: analytical and numerical studies Physical Review B: Condensed Matter and Materials Physics, 74 (18). 184424_1-184424_9. ISSN 1098-0121
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Official URL: http://prb.aps.org/abstract/PRB/v74/i18/e184424
Related URL: http://dx.doi.org/10.1103/PhysRevB.74.184424
Abstract
We study the locations of the gapless points which occur for quantum spin chains of finite length (with a twisted boundary condition) at particular values of the nearest-neighbor dimerization, as a function of the spin S and the number of sites. For strong dimerization and large values of S, a tunneling calculation reproduces the same results as those obtained from more involved field theoretic methods using the nonlinear σ-model approach. A different analytical calculation of the matrix element between the two Néel states gives a set of gapless points; for strong dimerization, these differ significantly from the tunneling values. Finally, the exact diagonalization method for a finite number of sites yields a set of gapless points which are in good agreement with the Néel state calculations for all values of the dimerization, but the agreement with the tunneling values is not very good even for large S. This raises questions about possible corrections to the tunneling results.
Item Type: | Article |
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Source: | Copyright of this article belongs to The American Physical Society. |
ID Code: | 45552 |
Deposited On: | 28 Jun 2011 05:44 |
Last Modified: | 18 May 2016 01:47 |
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