Density matrix renormalization group algorithm and the two-dimensional t-J model

We describe in detail the application of the recent non-Abelian density matrix renormalization group (DMRG) algorithm to the two-dimensional t-J model. This extension of the DMRG algorithm allows us to keep the equivalent of twice as many basis states as the conventional DMRG algorithm for the same amount of computational effort, which permits a deeper understanding of the nature of the ground state.