  We investigate phase separation of Bose-Einstein condensates (BECs) of
two-component atoms and one-component molecules with a homonuclear Feshbach
resonance. We develop a full model for dilute atomic and molecular gases
including correlation of the Feshbach resonance and all kinds of interparticle
interactions, and numerically calculate order parameters of the BECs in
spherical harmonic oscillator traps at zero temperature with the Bogoliubov's
classical field approximation. As a result, we find out that the Feshbach
resonance can induce two types of phase separation. The actual phase structures
and density profiles of the trapped gases are predicted in the whole parameter
region, from the atom dominant regime to the molecule dominant regime. We focus
on the role of the molecules in the phase separation. Especially in the atom
dominant regime, the role of the molecules is described through effective
interactions derived from our model. Furthermore we show that a perturbative
and semi-classical limit of our model reproduces the conventional atomic BEC
(single-channel) model.
