Unitary pole approximation for the Coulomb-plus-Yamaguchi potential and application to a three-body bound-state calculation.

The unitary pole approximation is used to construct a separable representation for a potential {ital U} which consists of a Coulomb repulsion plus an attractive potential of the Yamaguchi type. The exact bound-state wave function is employed. {ital U} is chosen as the potential which binds the proton in the 1{ital d}{sub 5/2} single-particle orbit in {sup 17}F. Using the separable representation derived for {ital U}, and assuming a separable Yamaguchi potential to describe the 1{ital d}{sub 5/2} neutron in {sup 17}O, the energies and wave functions of the ground state (1{sup +}) and the lowest 0{sup +} state of {sup 18}F are calculated in the core-plus-two-nucleons model solving the Faddeev equations.