Pd. Sacramento et Vr. Vieira, HALDANE-GAP IN A S=1 EXCHANGE MODEL WITH LONG-RANGE INTERACTIONS, Zeitschrift fur Physik. B, Condensed matter, 101(3), 1996, pp. 441-445
The ground-state properties of the S = 1 Haldane-Shastry model are stu
died using a modified Lanczos algorithm and diagonalizing exactly smal
l chains. We find evidence that, as for the antiferromagnetic Heisenbe
rg model, the spectrum shows a gap, in contrast to the S = 1/2 case. T
he correlation functions < S-z(O)S-z(m) > decay exponentially for larg
e m. We find that the correlation functions for the Haldane-Shastry mo
del decay faster than for the Heisenberg model. We estimate the infini
te system limit for the ground-state energy, value of the gap and corr
elation functions.