  The recently discovered charmed-strangemeson Ds0*(2317) has been speculated
to be a tetraquark mesonium. We study this suggestion with overlap fermions on
2+1 flavor domain wall fermion configurations. We use 4-quark interpolating
operatorswith Z4 grid sources on two lattices (16\times16\times16\times32 and
24\times24\times24 times64) to study the volume dependence of the states in an
attempt to discern the nature of the states in the four-quark correlator to see
if they are all two-meson scattering states or if one is a tetraquark mesonium.
We also use the hybrid boundary condition method for this purpose which is
designed to lift the two-meson states in energy while leaving the tetraquark
mesonium unchanged. We find that the volume method is not effective in the
present case due to the fact that the scattering states spectrum is closely
packed for such heavy states so that one cannot separate out individual
scattering states since the volume dependence is skewed as a result. However,
the hybrid boundary condition method works and we found that the four-quark
correlators can be fitted with a tower of two-meson scattering states. We
conclude that we do not see a tetraquark mesonium in the Ds0*(2317) meson
region.
