SINGLE-HOLE EFFECTIVE MASSES IN THE T-J MODEL

The ground state of a single hole in the one- and two-dimensional t-J model is studied for finite systems as a function of the phase in the kinetic energy term. The coherent effective hopping tc* and the incoherent hopping ti*, evaluated in this way, are connected via the conductivity sum rule. It is shown that for even and odd chains tc* ti*, while their reduction from the free value t remains small even for large J/t. The Bethe ansatz solution, obtained for J=2t, is consistent with the latter result, yielding tc*/t>0.938. In the 4×4 system, the phase variation yields a nontrivial energy manifold. The minimum appears to be near the (/2/2)-(0) line in the Brillouin zone for J/t<1, while moving towards the (/2/2) line for J1. © 1990 The American Physical Society.