Perturbation theory by flow equations: dimerized and frustrated S=1/2 chain

Authors
Knetter, C Uhrig, GS
Citation
C. Knetter et Gs. Uhrig, Perturbation theory by flow equations: dimerized and frustrated S=1/2 chain, EUR PHY J B, 13(2), 2000, pp. 209-225
Citations number
35
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
EUROPEAN PHYSICAL JOURNAL B
ISSN journal
14346028 → ACNP
Volume
13
Issue
2
Year of publication
2000
Pages
209 - 225
Database
ISI
SICI code
1434-6028(200001)13:2<209:PTBFED>2.0.ZU;2-J
Abstract
The flow equation method (Wegner, 1994) is used as continuous unitary trans formation to construct perturbatively effective Hamiltonians. The method is illustrated in detail for dimerized and frustrated antiferromagnetic S = 1 /2 chains. The effective Hamiltonians conserve the number of elementary exc itations which are S = 1 magnons for the dimerized chains. The sectors of d ifferent; number of excitations are clearly separated. Easy-to-use results for the gap, the dispersion and the ground state energies of the chains are provided.