Theoretical investigation of Bi-containing two dimensional topological insulators

In this study, the properties and interactions of Bi-containing two-dimensional topological insulators, known as nanotechnological materials, and their interaction with the molecules were investigated by modeling and simulation programs based on Density Functional Theory. The structural parameters and band gap values we have obtained are in accordance with the results in the literature. The phonon band structure results indicate that InBi and GaBi are stable in the groud state. According to the molecules dynamic results, the pristine structures are found to be stable. However, the results vacancy defect of molecular dynamics shows that only for InBi3 the structure is disrupted. When the band structures are examined, it is seen that in all vacancy defect cases, the topological insulator properties were disappear. Likewise, the atoms sent from outside to heal the vacancy-defect conditions have generally been successful, except for InBi3 and InBi. When the electric field is applied perpendicular to the surface, the band gaps increase for GaBi and InBi and decreases for GaBi3 and InBi3. The application of electric field also causes an increase in the lattice constant. When the surfaces are functionalized with certain atoms, binding energies between 1,60 – 6,50 eV have been obtained. In general, the binding energy of the atom increases from left to right in the periodic table. All materials functionalized with C atom are stable and continued to exhibit a topological insulator property. In addition, this stability and topological property are also avaible in the interaction of GaBi and InBi with O atom. Generally, small molecules have weak energy with pristine structures. However, a strong interaction energy was obtained for pristine GaBi3 and InBi3 with water. The interaction energy of the big molecules with the monolayers has bigger energies compared to others. Lastly, it has been determined that changing the total charge of the system does not affect the interaction energies so much.