  We propose an effective Ginzburg-Landau energy functional for superfluid
helium that is motivated by the ideal Bose gas model. The parameters of this
phenomenological model are adjusted to known properties of the bulk system. The
motivation and the field of applications of this model are quite similar to
that of the Psi theory by Ginzburg and Sobyanin. The correlation length, the
depression of the transition temperature in helium films and the density
profile at a boundary are calculated.
