We show that the Onsager-field theory for itinerant systems is also qu
ite useful for arbitrary filling of the two-dimensional (2D) and 3D Hu
bbard models in the weak to intermediate coupling of U, yielding vario
us magnetic properties in agreement with the results of quantum Monte
Carlo simulations and the two-particle self-consistent method of Ville
et al. Any small doping into the antiferromagnetic ground state of th
e half-filled 3D model introduces an incommensurate phase with a signi
ficant reduction due to fluctuations. [S0163-1829(98)00242-2].