We consider a set of three-cluster systems (4He, 7Li, 7Be,
8Be, 10Be) within a microscopic model which involves the
hyperspherical harmonics to represent intercluster motion. We selected such
three-cluster systems which have at least one binary channel. Our aim is to
study whether the hyperspherical harmonics are able and under what conditions
to describe two-body channel(s) (nondemocratic motion) or they are suitable for
describing three-cluster continuum only (democratic motion). It is demonstrated
that a rather restricted number of the hyperspherical harmonics allows us to
describe bound states and scattering states in two-body continuum for a
three-cluster system.Comment: 18 pages, 19 figures, extended version of the paper, new figures and
references added, submitted to Phys. Rev.