title: Spectral weight contributions of many-particle bound States and continuum.
abstract: Cluster expansion methods are developed for calculating the spectral weight contributions of multiparticle excitations--continuum and bound states--to high orders. A complete 13th order calculation is carried out for the alternating Heisenberg chain. For lambda=0.27, relevant to the material Cu(NO3)(2).2.5D(2)O, we present detailed spectral weights for the two-triplet continuum and all bound states. We also examine the variation of the relative weights of one- and two-particle states with bond alternation from the dimerized to the uniform chain limit.
authors.affiliation: School of Physics, University of New South Wales, Sydney NSW 2052, Australia.
authors.forename: Weihong
authors.initials: W
authors.lastname: Zheng
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hamer
authors.forename: Rajiv R P
authors.initials: RR
authors.lastname: Singh