scholarly journals Influence of Electric Field in the Adsorption of Atomic Hydrogen on Graphene

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
C. Cab ◽  
R. Medina-Esquivel ◽  
C. Acosta ◽  
J. Mendez-Gamboa ◽  
F. Peñuñuri ◽  
...  
Keyword(s):  
Electric Field ◽  
Charge Density ◽  
Electric Fields ◽  
Atomic Hydrogen ◽  
Density Functional ◽  
Electronic Charge ◽  
Generalized Gradient ◽  
Electronic Charge Density ◽  
System A ◽  
Spin Polarized

The influence of external electric field (EF) in the adsorption of atomic hydrogen on graphene (H/G) was studied by means of electronic structure calculations based on spin-polarized density functional theory with generalized gradient approximation (GGA). The changes in atomic hydrogen physisorption-chemisorption on graphene owed to EF (which ranged between −1.25 V/Å and 0.75 V/Å) were determined. Analysis of the electronic charge density for an H/G system explained the EF influences on the adsorption properties (analyzing changes in electronic charge density for H/G system). A decrease of more than 100% in the chemisorption barrier for an EF of −1.25 V/Å was found. The changes in the electronic charge density confirm the possibility of manipulating the physical-chemical adsorption of hydrogen on graphene by applying electric fields.

scholarly journals Electronic Structure, Electronic Charge Density, and Optical Properties Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jisha Annie Abraham ◽  
Gitanjali Pagare ◽  
Sankar P. Sanyal
Keyword(s):  
Optical Properties ◽  
Charge Density ◽  
Density Of States ◽  
Density Functional ◽  
Electronic Charge ◽  
Ambient Conditions ◽  
Electronic Charge Density ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Calculated Density

The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N(EF) shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail.

ELECTRONIC STRUCTURE AND ELECTRON CHARGE DENSITY IN THE INTERATOMIC BONDS OF BiSBr and BiSeBr CRYSTALS

2013 ◽  
Vol 27 (23) ◽  
pp. 1350122 ◽  
Author(s):  
A. AUDZIJONIS ◽  
R. SEREIKA
Keyword(s):  
Electronic Structure ◽  
Charge Density ◽  
Density Functional ◽  
Partial Density ◽  
Electronic Charge ◽  
Full Potential ◽  
Electron Charge ◽  
Generalized Gradient ◽  
Electron Charge Density ◽  
Plane Wave Method

Electronic structure and electronic charge density in the interatomic bonds are investigated with ab initio calculations based on the density-functional theory. The full potential linearized augmented plane-wave method was used with the generalized gradient approximation. Considering the partial density of states the electron charge density distribution in the Bi , S , Se and Br atomic bonds is caused by Bi-6p , S-3p , Se-4p , Br-4p orbital hybridization. Electronic charge distribution of one BiSBr and BiSeBr molecule range suggest that the Bi – S , Bi – Se and Bi – Br bonds are covalent–ionic type. Bi – S and Bi – Se bonds are strong covalent with a not great ionicity factor ([Formula: see text], Bi – S ; [Formula: see text], Bi – Se ). Bi – Br bonds are covalent type with a larger ionicity factor ([Formula: see text], Bi – Br ).

scholarly journals Electronic structure and magnetization of Zn1-xCoxO ternary alloys with zinc-blende, rocksalt and wurtzite phases

2021 ◽  
Author(s):  
K. Souleh ◽  
T. Smain ◽  
H. Lidjici ◽  
B. Lagoun ◽  
M. Boucenna ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Alloy System ◽  
Ternary Alloys ◽  
Electronic Charge ◽  
Electronic Charge Density ◽  
Wurtzite Phase ◽  
Zinc Blende ◽  
Spin Polarized ◽  
Co Concentration

Abstract First-principles all electrons density-functional calculations for the band structure and magnetization of Zn1 − xCoxO ternary magnetic alloys, in three phases namely zinc-blende, rocksalt and wurtzite have been reported. The computations are spin-polarized. An inspection of our electronic properties showed that the alloy system of interest exhibits a semiconducting character where the nature of the gap depends on the considered phase. An analysis of electronic charge density suggests that the bonding has a partially covalent character for ZnO which becomes weaker as far as the Co concentration increases. CoO is found to reach a total magnetization of 3 µB per cell for zinc-blende and rocksalt phases and 6 µB per cell for wurtzite phase.

Field Effect Modulation of Electrocatalytic Hydrogen Evolution at Back-Gated Two-Dimensional MoS2 Electrodes

2019 ◽  
Author(s):  
Yan Wang ◽  
Sagar Udyavara ◽  
Matthew Neurock ◽  
C. Daniel Frisbie
Keyword(s):  
Electric Field ◽  
Hydrogen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Electrode Materials ◽  
Density Functional Theory Calculations ◽  
Electronic Charge ◽  
Back Side ◽  
Gate Electrode ◽  
Conventional Manner

<div> <div> <div> <p> </p><div> <div> <div> <p>Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while sweeping the MoS2 electrochemical potential in a conventional manner in 0.5 M H2SO4 results in up to a 140-mV reduction in overpotential for hydrogen evolution at current densities of 50 mA/cm2. Tafel analysis indicates that the exchange current density is correspondingly improved by a factor of 4 to 0.1 mA/cm2 as gate voltage is increased. Density functional theory calculations support a mechanism in which the higher hydrogen evolution activity is caused by gate-induced electronic charge on Mo metal centers adjacent the S vacancies (the active sites), leading to enhanced Mo-H bond strengths. Overall, our findings indicate that the back-gated working electrode architecture is a convenient and versatile platform for investigating the connection between tunable electronic charge at active sites and overpotential for electrocatalytic processes on ultrathin electrode materials.</p></div></div></div><br><p></p></div></div></div>

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