  We use perturbed relativistic coupled-cluster (PRCC) theory to compute the
electric dipole polarizabilities $\alpha$ of Zn, Cd and Hg. The computations
are done using the Dirac-Coulomb-Breit Hamiltonian with Uehling potential to
incorporate vacuum polarization corrections. The triple excitations are
included perturbatively in the PRCC theory, and in the unperturbed sector, it
is included non-perturbatively. Our results of $\alpha$, for all the three
elements, are in excellent agreement with the experimental data. The other
highlight of the results is the orbital energy corrections from Breit
interactions. In the literature we could only get the data of Hg {E. Lindroth
et al., J. Phys. B 22, 2447 (1989)} and are near perfect match with our
results. We also present the linearized equations of the cluster amplitudes,
including the triple excitations, with the angular factors.
