La Struttura Elettronica dell'Arseniuro di Tantalio(Un Semimetallo di Weyl) Tramite Simulazioni Quanto-Meccaniche: L'Effetto Combinato dell'Accoppiamento Spin-Orbita, della Pressione,e dello Scambio Esatto di Fock

The Spin-Orbit Coupling effect is important to describe heavy elements and fast-moving particles. Thus, the latest implementation of such effects in the CRYSTAL code allowed us to provide an improved description of the electronic structure of the TaAs Weyl semi-metal. Furthermore, thanks to the Spin-Current Density Functional Theory (SCDFT) we were able to study the effect of the fraction of Exact Fock Exchange (α) on the material properties. All of this was done incrementally, by increasing α in the LDA family of functionals. In addition, we studied how the pressure affects the electronic structure of the TaAs system in a range comprised between 0 and 12 GPa. The effects of SOC, pressure and α were discussed more specifically with reference to topological features of the band structure of TaAs (i.e. Weyl nodes). The Weyl nodes correspond to pairs of isolated points where the valence and conduction bands touch one another. We demonstrated how one of the two Weyl node families is more stable than the other w.r.t. small external perturbations. Furthermore, we found an optimal window of α (10% to 20%) for which the electronic properties of the system are best described. In addition, we studied how the energy elevation of the nodes w.r.t. the Fermi level is affected by pressure and α, and found that these two factors display a competing effect.