  We present three complementary methods to study stationary nonlinear
solutions in one-dimensional nonlinear metal-dielectric structures. Two of them
use an approximate treatment of the Kerr type nonlinear term taking into
account only the leading electric field component, while the third one allows
for an exact treatment of the nonlinearity. A direct comparison of the results
obtained with all three models is presented and the excellent agreement between
them justifies the assumptions that have been used to construct the models. A
systematic study of the configurations made of two, three, or four layers, that
contain a semi-infinite Kerr type nonlinear dielectric, a metal film and linear
dielectrics is presented. Detailed analysis of properties, type and number of
solutions in these three types of structures is performed. The parameter ranges
where plasmon-soliton waves exist are found. The structures with realistic
opto-geometric parameters where plasmon-solitons exist at power levels already
used in spatial soliton studies are proposed and studied.
