Phases of polonium via density functional theory.
The thermodynamical properties of the main phases of metallic polonium are examined using density functional theory. The exceptional nature of the solid-solid phase transition of alpha to beta Po is underlined: it induces a lowering in symmetry, from cubic to rhombohedral, with increasing temperature. This is explained as the result of a delicate balance between bonding and entropic effects. Overall agreement with existing experimental data is good by state-of-the-art standards. The phonons of Po present Kohn anomalies, and it is shown that the effect of spin-orbit interactions is the inverse of that in normal metals: due to the nonspherical nature of the Fermi Surface, spin-orbit effects reduce nesting and harden most phonon frequencies.
Verstraete
Matthieu J
MJ
Nano-Bio Group and ETSF, Departamento Física de Materiales, Universidad País Vasco UPV/EHU, Centro Física de Materiales CSIC-UPV/EHU and DIPC, E-20018 San Sebastián, Spain. matthieu.jean.verstraete@gmail.com