Browsing by Author "Zeleke, Beletu"

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    First Principle Study of Electronic Structure of Gold Doped Graphene
    (Addis Ababa University, 2019-08-07) Zeleke, Beletu; Amente, Chernet (PhD)
    In this thesis _rst principle calculations with in density functional theory (DFT) of electronic structure of gold Au doped graphene is studied by using a plane wave pseudopotential method. We used local density approximation (LDA) and generalized gradient approximations (GGA) for the exchange correlation potential. In all calculations, the geometry optimization option was employed in alloying the structure to fully relax. The convergence of the system was checked by calculating total energy versus kinetic energy cutt-o_ and total energy versus the size of k-points set. Convergence was attained for graphene starting from 41Ryd or 557:6eV , hence used to reduce computational cost. A uniform mesh 0f 13 _ 13 _ 1 k-points was used since it gives a good convergence at a reasonable computational cost providing charge density results and lattice constant of 2:485_A. From the band structure of graphene the two bands touch each other at K-point. DOS plot also gives neither band gap between conduction and valence bands nor overlapping at the Fermi energy indicating that graphene is semi-conductor. Finally, in the band structure of Au doped graphene built in 13_13_1 super cell the _=__ band cross at Fermi level. As clear evidence of the interaction between Au dopant and the graphene, the Fermi level is now moved to the conduction band, and the DOS display a sharp peak at the Fermi level. Therefore, the doping of Au in the graphene makes graphene semi-metallic.