scholarly journals Effect of Doping Concentration on Structural Stability and Formation Energy of the Fluorine Doped Hexagonal Molybdenum Dioxide (MoO2). A First Principle Study.

2021 ◽  
pp. 55-59
Author(s):  
Yakubu Tanko ◽  
Alhassan Shuaibu ◽  
Aminu Abdulrahman ◽  
Oyedare Olusola ◽  
Mustapha Isa ◽  
...  
Keyword(s):  
Bond Length ◽  
Density Functional ◽  
Formation Energy ◽  
Doping Concentration ◽  
Generalized Gradient ◽  
Molybdenum Dioxide ◽  
Functional Theory ◽  
Free Atoms ◽  
The Stability ◽  
Quantum Espresso

The structural properties of undoped and Fluorine doped Hexagonal Molybdenum dioxide (MoO2) with different doping concentrations have been calculated using Density Functional Theory (DFT) within Generalized Gradient Approximation (GGA) as implemented in Quantum Espresso (QE). The calculated results were for the formation energy of 4.17%, 8.33%, 12.5%, of F doped MoO2 are 232.5eV, 463.0eV, and 698.5eV respectively, which show the variation of energy based on the increase in the doping concentration that led to having the breakage of bond in the structure of the compound. The undoped and 4.17% of F doped MoO2 have three free atoms, which maintain the stability of the structure, but when the doping concentration was increased, the bond breaks simultaneously which led to having four and five free atoms for 8.33%, and 12.5% of F doped MoO2 respectively. This makes 4.17% of F doped MoO2 with 17.09Ry more stable. Similarly, the bond length of undoped MoO2 was 2.2505pm, but when doped with 4.17% of F it changes to 2.3030pm which indicates a greater stability of the structure concentrations of the dopant above 4.17% reduced the bond length, which made the structure less stable.

Tuning Structural and Electronic Properties of Phosphorene with Vacancies

2020 ◽  
Vol 6 (1) ◽  
pp. 7-15
Author(s):  
N. Pantha ◽  
B. Chauhan ◽  
P. Sharma ◽  
N. P. Adhikari
Keyword(s):  
Magnetic Properties ◽  
Band Gap ◽  
Density Functional ◽  
Formation Energy ◽  
Single Layer ◽  
Generalized Gradient ◽  
Geometrical Structures ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Quantum Espresso

Two dimensional materials show multiple applications including in semiconductor devices and gaseous storage. We have carried out First-Principles calculations to study the geometrical structures, stability and electronic/magnetic properties of pristine as well as double vacancy phospherene. Calculations are based on Density Functional Theory (DFT) taking an account of van der Waals (vdW) interaction in the DFT-D2 approach within Generalized Gradient Approximation (GGA). Modeling and simulation have been performed with Quantum ESPRESSO (QE) codes. The supercell of 4×4 structure, whose building block is an orthogonal unit cell with four phosphorous atoms, is used to model the samples. Based on the stability of defected single layer phosphorene, a couple of structures (DV(5|8|5)-1 and DV(5|8|5)-2) have been considered to calculate their formation energy, band structure and other properties. Formation energy values find the former structure (DV(5|8|5)-1) more favorable to create than the later one. A band gap of 0.86eV for pristine phospherene, an excellent agreement with the experiment, validates the results of present calculations. The phosphorene with double vacancy, however, shows significant changes in electronic bands with reference to the pristine one. The band gap for DV(5|8|5)-1 and DV(5|8|5)-2 systems are found to be 1.01eV and 0.1 eV respectively. No magnetic moment in both the pure and defected (double vacancy) phospherene monolayer approves that only the vacancies are not enough to induce magnetic properties in phosphorene.

Stability and Physicochemical Principles for Icosahedral Ti12X (X = Li to Xe) Clusters: A DFT Study

2008 ◽  
Vol 8 (5) ◽  
pp. 2475-2478
Author(s):  
M. Salazar-Villanueva ◽  
P. H. Hernandez Tejeda ◽  
J. F. Rivas-Silva ◽  
J. A. Ascencio
Keyword(s):  
Density Functional ◽  
Chemical Affinity ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Stable Clusters ◽  
The Density Functional Theory ◽  
The Stability ◽  
Chemical Selectivity ◽  
Homo Lumo

Results about stability, electronic structure and characteristic electronic properties are reported for cluster structures based on icosahedra structure with a composition of Ti12X (X = Li to Xe) within the generalized gradient approximation of the density functional theory. It is demonstrated that several elements allow an improvement on the stability of Ti13 by a doping process where the central atoms is substituted. C, Si, P, Co, Ge, Ru and Te lead to the largest gain in energy, while the HOMO-LUMO maximum gap distinguishes to just C, Si, P and Te as the most probable to be found in experimental samples. The analysis included physicochemical study of the most stable clusters to predict chemical affinity and new properties. Results reported here are in agreement with partial studies of Ti12X but because of the considered elements, a new scope is open of possible application mainly in the fields as sensors, catalysis and medicine, where the chemical selectivity is an important parameter.

Structural and elastic properties of ZrN and HfN: ab initio study

2014 ◽  
Vol 92 (9) ◽  
pp. 1058-1061 ◽  
Author(s):  
Anurag Srivastava ◽  
Bhoopendra Dhar Diwan
Keyword(s):  
Elastic Properties ◽  
Density Functional ◽  
Zirconium Nitride ◽  
Energy Calculation ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Hafnium Nitride ◽  
Zinc Blende ◽  
The Density Functional Theory ◽  
The Stability

The present paper discusses the density functional theory based stability analysis of zirconium nitride and hafnium nitride in its rocksalt (B1), CsCl (B2), and zinc blende (B3) type phases. The ground state total energy calculation approach of the system has been used through the generalized gradient approximation parameterized with revised Perdew–Burke–Ernzerhof as exchange correlation functional. The present theoretical analysis confirms the stability trend of phases from most stable to less stable as B1 → B2 → B3. The study also reports the analysis of elastic properties of these nitrides in its most stable B1-type phase.

scholarly journals First-principles Study of Electronic and Magnetic Properties of Manganese Decorated Graphene

2016 ◽  
Vol 3 (1) ◽  
pp. 24 ◽  
Author(s):  
Bishnu Prasad Paudel ◽  
Nurapati Pantha ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Density Functional ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
Weak Binding ◽  
London Dispersion ◽  
The Stability ◽  
Quantum Espresso

<p>The functionalization of graphene by the addition of Manganese (Mn) atom to its surface has been investigated computationally by using density-functional theory (DFT) based first-principles method within DFT-D2 level of approximations. The calculations have been computed employing the Quantum ESPRESSO codes. The stability, geometrical structures, electronic and magnetic properties of pure and Mn adatom graphene systems have been studied. From the information of adsorption energies of Mn atom on the different sites of graphene, the top site is found to be the most favorable one for its adsorption. Present study finds that the London dispersion interaction plays a major role in the weak binding of Mn on graphene. The study of electronic and magnetic properties of Mn decorated graphene shows that the conduction and valence band are overlapped with finite density of states (DOS) at Fermi level. The dissimilar DOS for up and down spin calculations quantify magnetic moment as 5.48 μ<sub>B</sub> which is consistent with the previous study</p><p>Journal of Nepal Physical Society Vol.3(1) 2015: 24-34</p>

scholarly journals Hydrogen storage on platinum decorated graphene: A first-principles study

BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 113-122 ◽  
Author(s):  
S Lamichhane ◽  
N Pantha ◽  
NP Adhikari
Keyword(s):  
Binding Energy ◽  
First Principles ◽  
Density Functional ◽  
Pristine Graphene ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
London Dispersion ◽  
Quantum Espresso ◽  
London Dispersion Forces

Adsorption of gaseous/molecular hydrogen on platinum (Pt) decorated and pristine graphene have been studied systematically by using density functional theory (DFT) level of calculations implemented by Quantum ESPRESSO codes. The Perdew-Burke-Ernzerhof (PBE) type generalized gradient approximation (GGA) exchange-correlation functional and London dispersion forces have been incorporated in the DFT-D2 level of algorithm for short and long range electron-electron interactions, respectively. With reference to the binding energy of Pt on different symmetry sites of graphene supercells, the bridge (B) site has been predicted as the best adsorption site. In case of 3×3 supercell of graphene (used for detail calculations), the binding energy has been estimated as 2.02 eV. The band structure and density of states calculations of Pt adatom graphene predict changes in electronic/magnetic properties caused by the atom (Pt). The adatom (Pt) also enhances the binding energy per hydrogen molecule in Pt-graphene comparing to that in pristine graphene and records the values within the range of 1.84 eV to 0.13 eV for one to eight molecules, respectively. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10389 BIBECHANA 11(1) (2014) 113-122

Density functional theory study of transition metals doped B80 fullerene

2014 ◽  
Vol 13 (06) ◽  
pp. 1450050 ◽  
Author(s):  
Jianguang Wang ◽  
Li Ma ◽  
Yanhua Liang ◽  
Meiling Gao ◽  
Guanghou Wang
Keyword(s):  
Density Functional Theory ◽  
Outer Surface ◽  
Density Functional ◽  
Formation Energy ◽  
Magnetic Moments ◽  
Density Functional Theory Calculations ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Energy Gaps ◽  
The Stability

Density functional theory calculations have been carried out to investigate 3d, Pd and Pt transition metal (TM) atoms exohedrally and endohedrally doped B 80 fullerene. We find that the most preferred doping site of the TM atom gradually moves from the outer surface ( TM = Sc ), to the inner surface ( TM = Ti and V ) and the center ( TM = Cr , Mn , Fe and Zn ), then to the outer surface ( TM = Co , Ni , Cu , Pd , and Pt ) again with the TM atom varying from Sc to Pt . From the formation energy calculations, we find that doping TM atom can further improve the stability of B 80 fullerene. The magnetic moments of doped V , Cr , Mn , Fe , Co and Ni atoms are reduced from their free-atom values and other TM atoms are completely quenched. Charge transfer and hybridization between 4s and 3d states of TM and 2s and 2p states of B were observed. The energy gaps of TM @ B 80 are usually smaller than that of the pure B 80. Endohedrally doped B 80 fullerene with two Mn and two Fe atoms were also considered, respectively. It is found that the antiferromagnetic (AFM) state is more energetically favorable than the ferromagnetic (FM) state for Mn 2- and Fe 2@ B 80. The Mn and Fe atoms carry the residual magnetic moments of ~ 3 μB and 2 μB in the AFM states.

Study of first principles on anisotropy and elastic constants of YAl3 compound

2020 ◽  
Vol 98 (4) ◽  
pp. 357-363
Author(s):  
Tahsin Özer
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Data ◽  
Anisotropic Behavior ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Quantum Espresso

Using the density functional theory (DFT) calculations, the structural optimization of the YAl3 compound was performed on the generalized gradient approximation (GGA) with quantum ESPRESSO (QE) software. Elastic constants were calculated after the optimization process. Polycrystalline quantities, such as bulk and shear modulus, Young’s modulus, and Poisson’s ratio, were determined using calculated elastic constants. The anisotropy of the compound was studied in detail. As a result of the calculations made, it was observed that the YAl3 compound exhibited mechanically stable structure and anisotropic behavior. In the ht2-YAl3 phase, the effect of pressure on physical properties was investigated in detail. The obtained results were compared with the existing experimental and other theoretical data.

scholarly journals Optical Absorption and Reflectivity of Four 2D Materials: MoS2, MoP2, NbS2, and NbP2

2021 ◽  
Vol 8 ◽  
Author(s):  
E. Garcés ◽  
O. Salas ◽  
L. F. Magaña
Keyword(s):  
Optical Absorption ◽  
Density Functional ◽  
2D Materials ◽  
Energy Band Structure ◽  
Ultraviolet Region ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Quantum Espresso ◽  
Hexagonal Materials

We calculated the energy band structure and the optical absorption and reflectivity for each of the ultrathin 2D hexagonal materials MoS2, MoP2, NbS2, and NbP2. Our simulations included density functional theory, generalized gradient approximation (GGA), and the Quantum Espresso code. Other researchers already synthesized the first three materials. We obtained that NbP2 should be another hexagonal 2D material. In all cases in the infrared and visible ranges, the absorptions present much larger concerning graphene. However, the absorptions for MoP2, NbP2, and NbS2, are far more prominent concerning MoS2. In the ultraviolet region, the absorptions are like each other and differ from graphene. In all cases, the reflectivities are similar to each other and vary from graphene.

Understanding the Formation Energy of Transition Metal Hydrides

2002 ◽  
Vol 730 ◽  
Author(s):  
Huw J. Smithson ◽  
Dane Morgan ◽  
Anton Van der Ven ◽  
Chris Marianetti ◽  
Ashley Pedith ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Formation Energy ◽  
Metal Hydrides ◽  
Functional Theory ◽  
Hydride Formation ◽  
Transition Metal Hydrides ◽  
Inverse Stability ◽  
Host Metal ◽  
The Stability

AbstractA detailed analysis of the formation energies of transition metal hydrides is presented. The hydriding energies are computed for various crystal structures using Density Functional Theory. The process of hydride formation is broken down into three consecutive, hypothetical reactions in order to analyse the different energy contributions, and explain the observed trends. We find that the stability of the host metal is very significant in determining the formation energy, thereby providing a more fundamental justification for Miedema's “law of inverse stability” [1] (the more stable the metal, the less stable the hydride). The conversion of the host metal to the structure formed by the metal ions in the hydride (fcc in most cases) is only significant for metals with a strong bcc preference such as V and Cr - this lowers the driving force for hydride formation. The final contribution is the chemical bonding between the hydrogen and the metal. This is the only contribution that is negative, and hence favourable to hydride formation. We find that it is dominated by the position of the Fermi level in the host metal.

Novel Silicon–Carbon Fullerene-Like Nanostructures: An Ab Initio Study on the Stability of Si54C6 and Si60C6 Clusters

2006 ◽  
Vol 6 (1) ◽  
pp. 43-53
Author(s):  
Aravind Srinivasan ◽  
Asok K. Ray
Keyword(s):  
Density Functional ◽  
Basis Set ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Silicon Carbon ◽  
Double Zeta ◽  
Valence Electrons ◽  
Symmetry Constraints ◽  
Core Electrons ◽  
The Stability

Silicon fullerene like nanostructures with six carbon atoms on the surface of Si60 cages by substitution, as well as inside the cage at various symmetry orientations have been studied within the generalized gradient approximation to density functional theory. Full geometry optimizations have been performed without any symmetry constraints using the Gaussian 03 suite of programs and the LANL2DZ basis set. Thus, for the silicon atom, the Hay-Wadt pseudopotential with the associated basis set are used for the core electrons and the valence electrons, respectively. For the carbon atom, the Dunning/Huzinaga double zeta basis set is employed. Electronic and geometric properties of the nanostructures are presented and discussed in detail. It was found that optimized silicon–carbon fullerene like nanostructures have increased stability compared to bare Si60 cage and the stability depends on the orientation of carbon atoms, as well as on the nature of bonding between silicon and carbon atoms and also on the carbon–carbon bonding.

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