  The latest trend in studies of modern electronically and/or optically active
materials is to provoke phase transformations induced by high electric fields
or by short (femtosecond) powerful optical pulses. The systems of choice are
cooperative electronic states whose broken symmetries give rise to topological
defects. For typical quasi-one-dimensional architectures, those are the
microscopic solitons taking from electrons the major roles as carriers of
charge or spin. Because of the long-range ordering, the solitons experience
unusual super-long-range forces leading to a sequence of phase transitions in
their ensembles: the higher-temperature transition of the confinement and the
lower one of aggregation into macroscopic walls. Here we present results of an
extensive numerical modeling for ensembles of both neutral and charged solitons
in both two- and three-dimensional systems. We suggest a specific Monte Carlo
algorithm preserving the number of solitons, which substantially facilitates
the calculations, allows to extend them to the three-dimensional case and to
include the important long-range Coulomb interactions. The results confirm the
first confinement transition, except for a very strong Coulomb repulsion, and
demonstrate a pattern formation at the second transition of aggregation.
