  The interactions responsible for Feshbach resonances in binary atom
collisions produce a condensate of molecules in the atomic BEC-system. We
discuss the `ground state' of the condensate system and illustrate that its
properties differ quantitatively and qualitatively from the properties of a
single condensate with atom-atom interactions described by the effective
scattering length that characterizes the binary atomic collisions. We show, for
example, that the tunneling of atom pairs between the atomic and molecular
condensates lowers the energy and can bind the condensate system, giving it the
liquid-like property of a self-determined density.
