Abstract
Spectral densities are calculated for the dimerized and frustrated chain using the method of continuous unitary transformations. The transformation to an effective triplon model is realized in a perturbative fashion up to high orders about the limit of isolated dimers. An efficient description in terms of triplons (elementary triplets) is possible: a detailed analysis of the spectral densities is provided for strong and intermediate dimerization including the influence of frustration. Precise predictions are made for inelastic neutron scattering experiments probing the sector and for optical experiments (Raman scattering, infrared absorption) probing the sector. Bound states and resonances influence the important continua strongly. The comparison with the field theoretic results reveals that the sine-Gordon model describes the low-energy features for strong to intermediate dimerization only at critical frustration.
- Received 25 July 2003
DOI:https://doi.org/10.1103/PhysRevB.69.104417
©2004 American Physical Society