A. Fledderjohann et al., NUMERICAL EVALUATION OF FREQUENCY-MOMENT SUM-RULES FOR DYNAMICAL STRUCTURE FACTORS, Physical review. B, Condensed matter, 53(17), 1996, pp. 11543-11549
The frequency moments of the zero-temperature dynamical structure fact
or in the antiferromagnetic Heisenberg model are computed on rings up
to 28 sites. Finite-size effects are analyzed and the estimate of the
thermodynamical limit is compared with the two-spinon ansatz of Muller
and with a modification of this ansatz for the dynamical structure fa
ctor.