High pressure superconducting phase of BI3: an ab initio study
Abstract
Using the ab initio evolutionary algorithm for crystal structure prediction, we successfully obtained the high pressure crystal structure of BI3 with P21/c space group, which was characterized as the B2I6 dimer analogous to the diborane molecule. This structure has been supported by excellent agreement between the theoretical and experimental equations of state, X-ray diffraction data, and the positive pressure dependence of Tc. Moreover, the P21/c structure is both dynamically and mechanically stable through phonon and elastic constants calculations. Further analysis reveals a superconducting mechanism in which the vibrations of iodine atoms dominate the superconductivity of BI3. In addition, the positive pressure dependence Tc is mainly attributed to the increase of the EPC parameter λ, the logarithmic average phonon frequency ωlog, and the electronic density of states at the Fermi level N(εf).