Transition Metal Nitrides: A First Principles Study

2016 ◽  
Vol 35 (4) ◽  
pp. 389-398
Author(s):  
Ashish Pathak ◽  
A. K. Singh
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Density Functional ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Functional Theory ◽  
Melting Temperatures ◽  
Bonding Characteristics

AbstractThe present work describes the structural stability and electronic and mechanical properties of transition metal nitrides (TmNs: B1 cubic structure (cF8, Fm $$\overline 3 $$ m)) using first principles density functional theory (DFT) within generalized gradient approximation (GGA). The lattice constant of TmNs increases with increasing the atomic radii of the transition metals. Stability of the TmNs decreases from IVB to VIB groups due to increase in formation energy/atom. The bonding characteristics of these nitrides have been explained based on electronic density of states and charge density. All the TmNs satisfy Born stability criteria in terms of elastic constants except CrN and MoN that do not exist in equilibrium binary phase diagrams. The groups IVB and V–VIB nitrides are associated with brittle and ductile behaviour based on G/B ratios, respectively. The estimated melting temperatures of these nitrides exhibit reasonably good agreement with calculated with B than those of the C11 for all nitrides.

scholarly journals First-Principles Calculation of Transition Metal Hyperfine Coupling Constants with the Strongly Constrained and Appropriately Normed (SCAN) Density Functional and its Hybrid Variants

2019 ◽  
Vol 5 (4) ◽  
pp. 69 ◽  
Author(s):  
Dimitrios A. Pantazis
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Density Functional ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
First Principles Calculation ◽  
Chemical System ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Hyperfine Coupling Constants

Density functional theory (DFT) is used extensively for the first-principles calculation of hyperfine coupling constants in both main-group and transition metal systems. As with many other properties, the performance of DFT for hyperfine coupling constants is of variable quality, particularly for transition metal complexes, because it strongly depends on the nature of the chemical system and the type of approximation to the exchange-correlation functional. Recently, a meta-generalized-gradient approximation (mGGA) functional was proposed that obeys all known exact constraints for such a method, known as the Strongly Constrained and Appropriately Normed (SCAN) functional. In view of its theoretically superior formulation a benchmark set of complexes is used to assess the performance of SCAN for the challenging case of transition metal hyperfine coupling constants. In addition, two global hybrid versions of the functional, SCANh and SCAN0, are described and tested. The values computed with the new functionals are compared with experiment and with those of other DFT approximations. Although the original SCAN and the SCAN-based hybrids may offer improved hyperfine coupling constants for specific systems, no uniform improvement is observed. On the contrary, there are specific cases where the new functionals fail badly due to a flawed description of the underlying electronic structure. Therefore, despite these methodological advances, systematically accurate and system-independent prediction of transition metal hyperfine coupling constants with DFT remains an unmet challenge.

First-Principles Calculations of the Structure and Magnetic Phases of FeAs2 Compound under Pressure

SPIN ◽  
2018 ◽  
Vol 08 (04) ◽  
pp. 1850016 ◽  
Author(s):  
O. Sebaa ◽  
Y. Zaoui ◽  
K. O. Obodo ◽  
H. Bendaoud ◽  
L. Beldi ◽  
...  
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Density Functional ◽  
Stable Phase ◽  
Spin Orbit Coupling ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Functional Theory ◽  
Spin Ordering

Understanding of different magnetic configurations for the FeAs2 iron pnictide compound is carried out using first-principles studies based on spin density functional theory (DFT) within the generalized gradient approximation (GGA), including the spin–orbit coupling (SOC). The calculated stable phase is in the marcasite (Pnnm) with nonmagnetic spin-ordering. We find that the FeAs2 compound in the nonmagnetic (NM) marcasite phase undergoes pressure-induced phase transition to the antiferromagnetic (AFM1) marcasite phase at 12[Formula: see text]GPa, then to the AFM CuAl2 ([Formula: see text]4/mcm) phase at 63[Formula: see text]GPa. The phase transition is also accompanied by semiconducting (marcasite phase) to metallic (CuAl2 phase) transition. The calculated electronic density of states profile shows the hybridization of the Fe-3[Formula: see text] and As-4[Formula: see text] orbitals plays an important role in determining the electronic and magnetic characters of this compound. The associated phase transition results in increased Fe-3d orbitals around the Fermi energy level.

FIRST PRINCIPLES STUDY OF HCN ADSORPTION ON GRAPHENE DOPED WITH 5D TRANSITION METAL

2016 ◽  
Vol 23 (01) ◽  
pp. 1550095 ◽  
Author(s):  
HAI-KUAN DONG ◽  
YONG-PING WANG ◽  
LI BIN SHI
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Hydrogen Cyanide ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
B3lyp Method ◽  
Before And After ◽  
C And N

Hydrogen cyanide (HCN) adsorption on graphene doped with 5d transition metal (TM) is investigated by the first principles based on density functional theory. It is observed that Hg atom cannot be doped into graphene due to saturated valence electron configurations of 5d106s2. Three kinds of HCN adsorption configurations are investigated, in which H, C and N in HCN are close to the adsorption site, respectively. The most stable adsorption configuration is obtained by total energy optimization. HCN adsorption can be studied by adsorption energy and electron density difference. HCN can only be physisorbed on Ir, Pt and Au-doped graphenes, while chemisorption is observed for Lu, Hf, Ta, W, Re and Os-doped graphenes. The band structure is calculated by B3LYP and Generalized gradient approximation (GGA) functionals. It is observed from B3LYP method that the conductivity of Lu, Hf, Re and Os-doped graphenes does not obviously change before and after HCN adsorption. Ta and W-doped graphenes change from semiconductor to metal after adsorption of HCN molecule. The results indicate that Ta and W-doped graphenes may be a promising sensor for detecting HCN. This study provides a useful basis for understanding of a wide variety of physical properties on graphene.

Theoretical study on the structural, electronic and physical properties of layered alkaline-earth-group-4 transition-metal nitrides AEMN2

RSC Advances ◽  
2014 ◽  
Vol 4 (60) ◽  
pp. 31981-31987 ◽  
Author(s):  
Esther Orisakwe ◽  
Bruno Fontaine ◽  
Duncan H. Gregory ◽  
Régis Gautier ◽  
Jean-François Halet
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
Functional Theory ◽  
Group 4 ◽  
Structural And Electronic Properties

Thermodynamic, structural, and electronic properties of the layered ternary nitrides AEMN2 (AE = alkaline-earth; M = group 4 transition metal) both with the KCoO2 and α-NaFeO2 structure-types are examined within density-functional theory.

Site preference and atomic ordering in the ternary Rh5Ga2As: first-principles calculations

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nilanjan Roy ◽  
Sucharita Giri ◽  
Harshit ◽  
Partha P. Jana
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Density Functional ◽  
Structure Type ◽  
Site Preference ◽  
X Ray Diffraction ◽  
Atomic Ordering ◽  
Functional Theory ◽  
The Stability ◽  
Bonding Characteristics

Abstract The site preference and atomic ordering of the ternary Rh5Ga2As have been investigated using first-principles density functional theory (DFT). An interesting atomic ordering of two neighboring elements Ga and As reported in the structure of Rh5Ga2As by X-ray diffraction data only is confirmed by first-principles total-energy calculations. The previously reported experimental model with Ga/As ordering is indeed the most stable in the structure of Rh5Ga2As. The calculation detected that there is an obvious trend concerning the influence of the heteroatomic Rh–Ga/As contacts on the calculated total energy. Interestingly, the orderly distribution of As and Ga that is found in the binary GaAs (Zinc-blende structure type), retained to ternary Rh5Ga2As. The density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) are calculated to enlighten the stability and bonding characteristics in the structure of Rh5Ga2As. The bonding analysis also confirms that Rh–Ga/As short contacts are the major driving force towards the overall stability of the compound.

Flexoelectricity in atomic monolayers from first principles

Nanoscale ◽  
2020 ◽  
Author(s):  
Shashikant Kumar ◽  
David Codony ◽  
Irene Arias ◽  
Phanish Suryanarayana
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Functional Theory ◽  
Group Iii ◽  
Flexoelectric Effect ◽  
Metal Dichalcogenides

We study the flexoelectric effect in fifty-four select atomic monolayers using ab initio Density Functional Theory (DFT). Specifically, considering representative materials from each of Group III monochalcogenides, transition metal dichalcogenides...

Oxygen-evolution reactions (OER) on transition-metal-doped Fe3Co(PO4)4 iron-phosphate surfaces: a first-principles study

2021 ◽  
Author(s):  
Yogeshwaran Krishnan ◽  
Sateesh Bandaru ◽  
Niall J. English
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Oxygen Evolution ◽  
First Principles ◽  
Density Functional ◽  
Iron Phosphate ◽  
Functional Theory ◽  
First Principles Study ◽  
Metal Doped ◽  
Catalyst Surfaces

A series of transition-metal-doped Fe1−xMxCo(PO4)4(010) and Fe3Co1−xMx(PO4)4(010) electro-catalyst surfaces (with M = Mn, Os, Ru, Rh and Ir) have been modelled via density-functional theory (DFT) to gauge their oxygen-evolution reactions (OER).

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