مطالعه ويژگي‌هاي الكتروني و اپتيكي تك لايه‌هاي پلاتين دي تلوريد( (PtTe2و پلاتين دي سلنيد(PtSe2)

Study of electronic an‎d optical properties of Platinum Ditelluride (PtTe2) an‎d Platinum Diselenide (PtSe2) monolayers

فيزيك ماده چگال

In this thesis, the structural, electronic, optical, an‎d topological properties of bulk an‎d monolayer forms of PtSe₂ an‎d PtTe₂ are investigated. The calculations were performed based on density functional theory (DFT) using the augmented plane wave plus local orbitals (APW+lo) method as implemented in the WIEN2k code. Various exchange-correlation approximations were employed, including the generalized gradient approximation (GGA-PBE), the local density approximation (LDA), the modified Becke-Johnson (mBJ) potential, an‎d the Engel-Vosko GGA (GGA-EV). The topological phases of both the bulk an‎d nanolayer structures of PtSe₂ an‎d PtTe₂ were explored. Structural parameters such as lattice constants, bulk modulus, an‎d its prossure derivatives were calculated, showing that the GGA approach with spin-orbit coupling yields results in better agreement with experimental data. The electronic properties of the nanolayers were also analyzed. The density of states (DOS) results indicate that while the bulk phases are metallic, the monolayer structures exhibit semiconducting behavior. Ban‎d structure analysis shows that neither the bulk nor the monolayer structure exhibit ban‎d inversion, confirming their trivial topological character. Furthermore, the effect of prossure on the topological phase was examined, revealing no significant influence. Optical properties for both bulk an‎d monolayer systems were obtained, an‎d several key optical indicators such as refractive index, reflectivity, absorption coefficient, extinction coefficient, an‎d energy loss function were analyzed.

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