In high-intensity accelerators the dominant nonlinear forces are due the sp
ace charge but the effect of multipolar errors and synchro-betatron couplin
g should be taken into account. The micromaps approach allows, for a linear
lattice, to iteratively obtain the self-consistent solution and can be ext
ended to include the lattice nonlinearities. We investigate here the conver
gence of the method for a constant focusing and a FODO cell. In both cases
we prove the convergence to the exact solution up to a limit current corres
ponding to a significant limit tune shift.