  The Fock-space Hamiltonian truncation method is developed further, paying
particular attention to the treatment of the scalar field zero mode. This is
applied to the two-dimensional Phi^4 theory in the phase where the Z_2-symmetry
is spontaneously broken, complementing our earlier study of the Z_2-invariant
phase and of the critical point. We also check numerically the weak/strong
duality of this theory discussed long ago by Chang.
