Phase separation and stripe formation in the two-dimensional t-J model: A comparison of numerical results

We make a critical analysis of numerical results for and against phase sepa ration and stripe formation in the t-J model. We argue that the frustrated phase separation mechanism for stripe formation requires phase separation a t too high a doping for it to be consistent with existing numerical studies of the t-J model. We compare variational energies for various methods, and conclude that the most accurate calculations for large systems appear to b e from the density-matrix renormalization group. These calculations imply t hat the ground state of the doped t-J model is striped, not phase separated .