arXiv:cond-mat/0412358 · Physical Review B
Contractor renormalization group theory of SU(N) chains and ladders
Peng Li, Shun-Qing Shen
Abstract
The contractor renormalization group (CORE) method is applied to the $\mathrm{SU}(N)$ chain and ladders in this paper. In our designed schemes, we show that these two classes of systems can return to their original form of Hamiltonian after CORE transformation. Successive iteration of the transformation leads to a fixed point so that the ground state energy and the energy gap to the ground state can be deduced. The result of $\mathrm{SU}(N)$ chain is compared with the one by Bethe ansatz method. The transformation on spin-$1∕2$ ladders gives a finite gap in the excited energy spectra to the ground state in an intuitive way. The application to SU(3) ladders is also discussed.