  In this paper, we consider an exotic baryon (pentaquark) as a bound state of
two-particle systems composed of a baryon (nucleon) and a meson.We used a
baryon - meson picture to reduce a complicated five-body problem to a simple
two-body problems. The homogeneous Lippmann-Schwinger integral equation is
solved in configuration space by using one pion exchange potential. We
calculate the masses of pentaquarks $\theta_{c}(uudd\bar{c})$,
$\theta_{b}(uudd\bar{b})$.
