Revealing atypical ground state structures of III-Ununpentium compounds

Abstract

Using first-principles calculations within density functional theory, we explore the electronic structure and ground state properties of new hypothetical III–V compounds formed by the group III elements (B, Al, Ga, In, and Tl) and superheavy element of group V: Ununpentium (Uup). We find that wurtzite structure is the ground state phase of BUup; whereas AlUup, GaUup, InUup and TlUup prefer tetragonal PbO phase. Omission of spin-orbit interaction leads to minor changes in ground state structural parameters, but without affecting the ground state phase stability. In contrast, disregarding relativistic effects is instead dramatic: the wurtzite structure becomes in such a case the ground state phase of all the III-Uup compounds. Our studies reveal that the proposed hypothetical new IIIUup family divulges surprising features compared with other III–V semiconductors. Specifically, all compounds are found metallic, the partial density of states display strong s-d coupling, strong presence of cation-s states, and exhibit an almost equal contribution of cation and anion(Uup) p-states in the vicinity of Fermi level. This suggests the possibility of strong covalent bonds between III elements and Uup. Furthermore, the calculated partial phonon density of states shows the dynamical stabilities of the predicted ground state phase of all III-Ununpentium compounds.