  By applying the Lehmann-Symanzik-Zimmermann (LSZ) reduction formalism, we
study the S matrix of collective field theory in which fermi energy is larger
than the height of potential. We consider the spatially symmetric and
antisymmetric boundary conditions. The difference is that S matrices are
proportional to momenta of external particles in antisymmetric boundary
condition, while they are proportional to energies in symmetric boundary
condition. To the order of $g_{st}^2$, we find simple formulas for the S matrix
of general potential. As an application, we calculate the S matrix of a case
which has been conjectured to describe a "naked singularity".
