  The Coulomb blockade in an open quantum dot connected to a bulk lead by a
single mode point contact is studied numerically using the path-integral Monte
Carlo method. The Coulomb oscillation of the average charge and capacitance of
the dot is investigated, and is compared with the analytic expression for
strong tunneling. At the degeneracy point, we observe logarithmic divergence of
the capacitance for strong backscattering at the point contact. This
observation supports the conjecture that the nature of the present system at
the degeneracy point is described by the two-channel Kondo problem for an
arbitrary strength of tunneling.
