Interaction-round-a-face density-matrix renormalization-group method

A brief review of the interaction-round-a-face (IRF) density-matrix renormalization-group (DMRG) method. We have demonstrated the numerical superiority of IRF-DMRG method applied to SU(2) invariant quantum spin chains over the conventional DMRG. The ground state energy densities and the gap energies of both $S = 1$ and $S = 2$ spin chains can be calculated using the IRF-DMRG without extensive computations. We have also studied the effect of tuning boundary interaction $J_{\rm end}^{~}$ at both ends of the chain from the IRF view point. It is clearly observed that the magnon distribution is uniform when the best $J_{\rm end}^{~}$ is chosen.