Coupled cluster calculation of deformed nuclei.

We studied the ground states of deformed nuclei with the coupled-cluster method. The reference state of the nuclei is generated by deformed Hartree-Fock using the newly developed chiral potential including the $\Delta $ degree of freedom. The normal ordered interaction is transformed into a natural orbit and then truncated to affordable model space. We performed coupled-cluster calculation without symmetry restoration based on the fact that the uncertainties for lacking angular momentum projection are identical to that from triple up to A-particle-A-hole excitations, which is well controlled in the coupled-cluster theory. We calculated the ground state energy and charge radii of even-even nuclei from Z$=$20-30 and N$=$24-40 and have good agreement with the data.