Systematic analysis of the deformations of proton and neutron densities in
even-even C isotopes was done based on the method of antisymmetrized molecular
dynamics. The E2 transition strength was discussed in relation to the
deformation. We analyze the B(E2;21+→01+) in 16C, which has been
recently measured to be abnormally small. The results suggest the difference of
the deformations between proton and neutron densities in the neutron-rich C
isotopes. It was found that stable proton structure in C isotopes plays an
important role in the enhancement the neutron skin structure as well as in the
systematics of B(E2) in the neutron-rich C.Comment: submitted to Phys.Rev.