The Structural, Mechanical, Lattice Dynamical, and Thermal Properties of 3D Dirac Semimetals BaXBi (X=Cu, Ag, Au) from First-Principles Calculations

Abstract

The investigation of structural, mechanical, vibrational, and thermal properties of 3D Dirac semimetal BaXBi (X = Cu, Ag, Au) has been executed within density functional theory for the first time in detail. Available experimental lattice parameters are consistent with obtained data. The mechanical stability conditions for hexagonal structure are confirmed by obtained elastic constants. They are used to find out bulk modulus, B/G ratio, shear ratio, Poisson's ratio, Debye temperature, and minimum thermal conductivity of the materials. The results reveal that these semimetals are in brittle manner. BaCuBi is the hardest material among the compounds. Bonding character for all compounds is dominantly ionic. BaAuBi has the lowest thermal conductivity. Next, vibrational properties are examined and discussed. The crystals are also found to be dynamically stable because there are no negative frequencies in all k-direction of the crystal. Lastly, the thermodynamic properties have been performed and discussed. This work will provide useful information for both ZrBeSi-type structure compounds and 3D Dirac semimetals.