We study the finite-size behavior of the low-lying excitations of spin-1/2 Heisenberg chains with dimerization and next-to-nearest neighbors interaction J2. The numerical analysis, performed using density-matrix renormalization group, confirms previous exact diagonalization results and shows that, for different values of the dimerization parameter d, the elementary triplet and singlet excitations present a clear scaling behavior in a wide range of l=L/x (L is the length of the chain and x is the correlation length). At J2 = J2c, where no logarithmic corrections are present, we compare the numerical results with finite-size predictions for the sine-Gordon model obtained using Luscher's theory. For small d we find a very good agreement for l >= 4 or 7 depending on the excitation considered.

Scaling of excitations in dimerized and frustrated spin-1/2 chains

DEGLI ESPOSTI BOSCHI, CRISTIAN;ORTOLANI, FABIO;PASINI, STEFANO
2005

Abstract

We study the finite-size behavior of the low-lying excitations of spin-1/2 Heisenberg chains with dimerization and next-to-nearest neighbors interaction J2. The numerical analysis, performed using density-matrix renormalization group, confirms previous exact diagonalization results and shows that, for different values of the dimerization parameter d, the elementary triplet and singlet excitations present a clear scaling behavior in a wide range of l=L/x (L is the length of the chain and x is the correlation length). At J2 = J2c, where no logarithmic corrections are present, we compare the numerical results with finite-size predictions for the sine-Gordon model obtained using Luscher's theory. For small d we find a very good agreement for l >= 4 or 7 depending on the excitation considered.
D. Controzzi; C. Degli Esposti Boschi; F. Ortolani; S. Pasini
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/22013
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