Electronic, topological phase and optical properties of XPdBi (X = Lu, Sc) nano-layers

• A comparative study on the optical properties of XPdBi nano-layers is carried out.
• The first and second ScPdBi nano-layers have topologically trivial surface states.
• The LuPdBi nano-layer with 27.196 Å thickness has topological surface states.
• The electric field gradient of XPdBi nano-layers surface atoms is studied.
• The charge density distribution and bonding between surface atoms are studied.

The electronic and optical properties of XPdBi (X = Lu, Sc) nano-layers are investigated in the framework of first principles density functional theory by Wien2k code. The exchange-correlation potential is calculated within the generalized gradient approximation and Engel-Vosco generalized gradient approximation. The effect of nano-layer thickness on the electron density of states, energy gap and topological phase of these nano-layers is studied and compared. The surface states of LuPdBi nano-layers undergo a topological phase transition with increasing the thickness. The charge density of XPdBi nano-layers surface atoms with two different thicknesses is investigated. The results show the ionic bonding between X and Bi surface atoms of these nano-layers. The electric field gradient and the interaction of electronic orbital wave functions with the electronic cloud distribution of these nano-layers surface atoms with different thicknesses are calculated and compared. The anisotropic optical response of these nano-layers to two electromagnetic waves polarizations is investigated. Furthermore, the effect of nano-layer thickness on the optical properties of these nano-layers is studied in the 0–35 eV energy range.