  We employ a fully relativistic coupled-cluster theory to calculate the
ground-state electric dipole polarizability and electron correlation energy of
superheavy elements Cn, Nh$^+$ and Og. To assess the trend of electron
correlation as function of $Z$, we also calculate the correlation energies for
three lighter homologs--Zn, Cd and Hg; Ga$^+$, In$^+$ and Tl$^+$; Kr, Xe and
Rn--for each superheavy elements. The relativistic effects and quantum
electrodynamical corrections are included using the Dirac-Coulomb-Breit
Hamiltonian with the corrections from the Uehling potential and the
self-energy. The effects of triple excitations are considered perturbatively in
the theory. Furthermore, large bases are used to test the convergence of
results. Our recommended values of polarizability are in good agreement with
previous theoretical results for all SHEs. From our calculations we find that
the dominant contribution to polarizability is from the valence electrons in
all superheavy elements. Except for Cn and Og, we observe a decreasing
contribution from lighter to superheavy elements from the Breit interaction.
For the corrections from the vacuum polarization and self-energy, we observe a
trend of increasing contributions with $Z$. From energy calculations, we find
that the second-order many-body perturbation theory overestimates the electron
correlation energy for all the elements considered in this work.
