Interaction-round-a-face density-matrix renormalization-group method applied to rotational-invariant quantum spin chains

An interaction-round-a-face density-matrix renormalization-group (IRF-DMRG) method is developed for higher integer spin chain models which are rotational invariant. The expressions of the IRF weights associated with the nearest-neighbor spin-S interaction S-i. Si+1 are explicitly derived. Using the IRF-DMRG with these IRF weights, the Haldane gaps Delta and the ground state energy densities eo for both S = 1 and S = 2 isotropic antiferromagnetic Heisenberg quantum spin chains are calculated by keeping up to only m = 90 states.