  The coherent muon-electron conversion rates in various nuclei are calculated
for general lepton flavor violating interactions. We solve the Dirac equations
numerically for the initial state muon and the final state electron in the
Coulomb force, and perform the overlap integrals between the wave functions and
the nucleon densities. The results indicate that the conversion branching ratio
increases for a light nucleus up to the atomic number Z ~ 30, is largest for Z
= 30 -- 60, and becomes smaller for a heavy nucleus with Z > (~ 60). We also
discuss the uncertainty from the input proton and neutron densities. The atomic
number dependence of the conversion ratio calculated here is useful to
distinguish theoretical models with lepton flavor violation.
