  The influence of an external constant and homogeneous magnetic field H on the
phase structure of the P-symmetric, chiral invariant 3-dimensional field theory
model with two four-fermion interaction structures is considered. An arbitrary
small (nonzero) magnetic field is shown to induce spontaneous violation of the
initial symmetry (magnetic catalysis). Moreover, vacuum of the model at H>0 can
be either P-symmetric or chiral invariant, depending on the values of the
coupling constants.
