  The Gross-Pitaevskii equation with a local cubic nonlinearity that describes
a many-dimensional system in an external field is considered in the framework
of the complex WKB-Maslov method. Analytic asymptotic solutions are constructed
in semiclassical approximation in a small parameter $\hbar$, $\hbar\to 0$, in
the class of functions concentrated in the neighborhood of an unclosed surface
associated with the phase curve that describes the evolution of surface vertex.
The functions of this class are of the one-soliton form along the direction of
the surface normal. The general constructions are illustrated by examples.
