Note that the quantities in rows 1-3 and the exchange coupling parameters in rows 4 and 5 are calculated with two very different methods and codes. See Methods section for details. ** Calculated/experimental values.

No abstract

We report an ab initio study of the effect of pressure on vibrational and electronic properties of K 3 Bi and Rb 3 Bi in the cubic F m3m structure. It is shown that the high-temperature cubic phase of K 3 Bi and Rb 3 Bi is dynamically unstable at T = 0 but can be stabilized by pressure. The electronic spectra of alkali bismuthides are found to possess the bulk band touching at the Brillouin zone center and an inverted spin-orbit bulk band structure. Upon hydrostatic compression the compounds transform from the topologically nontrivial semimetal (K 3 Bi)/metal (Rb 3 Bi) into a trivial semiconductor (metal) with a conical Dirac-type dispersion of electronic bands at the point of the topological transition. In K 3 Bi the dynamical stabilization occurs before the system undergoes the topological phase transition.