  Exact expressions of the Pauli exclusion operator Q in the nuclear matter
calculation are presented in detail. Exact formulae are also given for the
calculations of the single-particle-potential energy and the binding energy per
nucleon with the exact Q operator. Numerical calculations of the G matrix in
the lowest-order Brueckner theory are carried out to check the reliability of
the standard angle-average approximation for the
  Q operator by employing the Bonn B and C NN potentials. It is observed that
the exact treatment of the operator Q brings about non-negligible and
attractive contributions to the binding energy.
