Unusual competition of structural phases and semi-conducting behaviour of bands in superheavy Copernicium

In this letter we address the problem of phase stability in the relatively new element 112, namely Copernicium (Cn). The ground state properties as well as the thermodynamic quantities were computed from a first-principles approach based on the local density approximation with spin orbit (SO) consideration. We found that relativistic effects play a vital role in the phase stability and electronic properties of Cn. The obtained results reveal some unusual energetic competition between the crystallographic forms that Cn may adopt, i.e., sc, bcc, fcc and hcp. Nevertheless, relativistic SO coupling increases the energetic stability of the bcc phase over the other structures; moreover dynamical calculations via phonon dispersion provide strong support for our findings. Band structure results indicate that Copernicium is at least a semiconductor in all possible phases. The valence bands of Cn have strong 6 d character, with a significant mixing between the fully occupied 7 s and 6 d bands.