First-principle study of geometric stabilities, electronic and magnetic properties of low coverage vanadium adsorption on graphene

Stable geometries, electronic and magnetic properties of low coverage vanadium (V) atoms adsorption on graphene sheet have been investigated by first principles calculations, using generalized gradient approximation. Calculation shows that center of the ring is energetically favorable for both V adatom and perpendicular dimer after relaxation. Moreover, the proportion of orbital contribution of C-V bonding are mainly dominated by 2pz orbital of C and partially occupied by the 3d like states of V. It is also found that the low coverage V atom adsorbed graphene system is metallic and magnetic, and has demonstrated additional hint on its usefulness in magnetic devices

Effect of gallium and arsenide adsorbed on graphene : a first-principles study on structural and electronic properties

In this study, the adsorption influence of two different metals, gallium (Ga) and arsenide (As) adatoms on the stabilities and electronic structure of single graphene layer has been systematically studied using first-principles pseudopotentials calculations within the framework of density functional theory (DFT). The generalized gradient approximation used is PW91 exchange-correlation functional. The results of our calculations reveal that the adsorption of Ga atom on graphene resulted in electron transfer mainly from p-orbital of the Ga adatom to graphene and subsequently, altered the electronic state of graphene by shifting the Fermi level away from Dirac point, up to ∼1.5 eV. Meanwhile, the d-orbitals of Ga adatom have spin polarization at the Fermi level where the minority spin d-orbitals are unoccupied. The As adatom was found to have larger adsorption energy value on H, B and T sites of graphene compared to Ga adatom. Thus, we described this energy difference as a result of the bonding configurations between both Ga and As atoms with carbon in the graphene structure. While B-site favored the adsorption of arsenic adatom, we found that the most favored adsorption site for Ga adatom on graphene is above H-sites

Spectrum-based Fault Localization Techniques Application on Multiple-Fault Programs: A Review

Software fault localization is one of the most tedious and costly activities in program debugging in the endeavor to identify faults locations in a software program. In this paper, the studies that used spectrum-based fault localization (SBFL) techniques that makes use of different multiple fault localization debugging methods such as one-bug-at-a-time (OBA) debugging, parallel debugging, and simultaneous debugging in localizing multiple faults are classified and critically analyzed in order to extensively discuss the current research trends, issues, and challenges in this field of study. The outcome strongly shows that there is a high utilization of OBA debugging method, poor fault isolation accuracy, and dominant use of artificial faults that limit the existing techniques applicability in the software industry

Density functional study of manganese atom adsorption on hydrogen-terminated armchair boron nitride nanoribbons

In this paper, we have investigated stable structural, electric and magnetic properties of manganese (Mn) atom adsorption on armchair hydrogen edge-terminated boron nitride nanoribbon (A-BNNRs) using first principles method based on density-functional theory with the generalized gradient approximation. Calculation shows that Mn atom situated on the ribbons of A-BNNRs is the most stable configuration, where the bonding is more pronounced. The projected density of states (PDOS) of the favored configuration has also been computed. It has been found that the covalent bonding of boron (B), nitrogen (N) and Mn is mainly contributed by s, d like-orbitals of Mn and partially occupied by the 2p like-orbital of N. The difference in energy between the inner and the edge adsorption sites of A-BNNRs shows that Mn atoms prefer to concentrate at the edge sites. The electronic structures of the various configurations are wide, narrow-gap semiconducting and half-metallic, and the magnetic moment of Mn atoms are well preserved in all considered configurations. This has shown that the boron nitride (BN) sheet covered with Mn atoms demonstrates additional information on its usefulness in future spintronics, molecular magnet and nanoelectronics devices

Low coverage palladium adsorption on graphene: first principles study

In this paper, we investigate stable geometries, electronic and magnetic properties of low coverage palladium (Pd) atom adsorption on graphene using first principles calculations with the generalized gradient approximation. Calculations show that single Pd atom located at the top of carbon atom is the energetically favorable configuration, and is found to be semiconductor and non-magnetic. We also compute the projected density of states (PDOS) around Fermi level and beyond. It is found that, C-Pd covalent interaction is mainly dominated by 2 pz of C, 5s and 4d like states of Pd. For low coverage stable Pd dimer, the adsorption is characterized by strong hybridization between the palladium atoms and the two carbon atoms bonded directly to it. A much weakening of Pd–Pd bond is observed and the C-Pd covalent bonds mainly dominate by 2pz of C orbital indicating that planar coating can be achieved. Thus, this work reveals that uniform coating of Pd atom can be achieved and may be useful in transport measurements

Effect of Cu and Co Dopıng on the Structural Propertıes of ZnO Nanopartıcles

CuxCo0.1Zn0.9-xO nanoparticles with different doping concentration (x=0.0, 0.05, 0.1, 0.15, and 0.2) has been successfully synthesized by microwave assisted combustion synthesis method using urea as a fuel. The structural, morphological, and compositional properties of these nanoparticles were investigated by X-ray diffraction (XRD), Scanning electron microscopes (FE-SEM JEOL-7001), and Energy-dispersive X-ray spectroscopy (EDX), respectively. The structural properties showed the formation of Wurtzite structure of ZnO,with nine prominent peaks in which the strong diffraction peaks appear in (100), (002) and (101), respectively, thereis a trace related to the Cu ions is observed and its diffraction peak increase with an increase in Cu concentration. The average size of the nanoparticles was estimated using Debye-Scherrer’s equation where the average size lie between 32.65 and 41.15nm. Scanning electron microscopes (SEM) showed that smaller crystallites have sizes smaller than 100nm, no indication of phase separation and little agglomeration was observed. Moreover, Energy-dispersive X-ray spectroscopy (EDX) confirmed that the chemical composition of the samples tallies with the synthesis results.Keywords: Nanoparticles, Zinc oxide, Semiconductor, Combustion synthesis method, Structural propertie