The power-Lanczos method, a Green's function Monte-Carlo simulation. is use
d to calculate the energies of the two-dimensional t-J model up to 122 site
s. The phase boundary of phase separation of the model is then determined b
y the Maxwell construction. Our conclusion is that there is no phase separa
tion for J less than or equal to 0.4. (C) 2001 Elsevier Science B.V. All ri
ghts reserved.