Elastic and Electronic Properties of Mg2Ca and Mg2Y Phases

2011 ◽  
Vol 233-235 ◽  
pp. 2231-2238 ◽  
Author(s):  
Meng Xue Zeng ◽  
Bi Yu Tang ◽  
Li Ming Peng ◽  
Wen Jiang Ding
Keyword(s):  
Mechanical Properties ◽  
Electronic Properties ◽  
Structural Stability ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Underlying Mechanism ◽  
Point Of View ◽  
Electronic Density ◽  
Energetic Point ◽  
Two Phases

Elastic and electronic properties of Mg2Ca and Mg2Y phases were investigated from first-principles calculations based on density functional theory. The optimized lattice parameters were found to be in excellent agreement with the available experimental value, and the structural stability was also studied from the energetic point of view. The five independent elastic constants were calculated, then the bulk modulus B, shear modulus G, Young’s modulus E and Poisson’s ratio ν of polycrystalline aggregates were derived, and the relevant mechanical properties Mg2Ca and Mg2Y phases were also further discussed. The elastic anisotropy of the two phases was also discussed in details. Finally, the electronic density of states and charge density distribution were also calculated to reveal the underlying mechanism of structural stability and mechanical properties.

Stability, Mechanical Properties and Electronic Properties of X3Si (X=V, Nb, Cr, Mo and W) from First Principles Calculations

2018 ◽  
Vol 913 ◽  
pp. 596-606
Author(s):  
He Wei ◽  
Yin Li Chen ◽  
Lan Su
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Transition Metal ◽  
Electronic Properties ◽  
Density Functional ◽  
Metal Silicide ◽  
Electronic Density ◽  
Temperature Oxidation ◽  
Transition Metal Silicide ◽  
Metastable Structure

The transition metal silicide X3Si (X = V, Nb, Cr, Mo and W) was characterized by its low density, high melting point, high temperature hardness, high temperature resistance to wear, high temperature oxidation resistance and corrosion resistance in this paper. For the fields such as aerospace, gas turbine etc, with the application of a new generation of high temperature structural materials, transition metal silicide will be one of their candidate materials. The stability, crystal structure, mechanical properties, electronic properties, Debye temperature and hardness of X3Si(X=V, Nb, Cr, Mo and W) compounds were calculated employing electronic density functional theory (DFT) and the generalized gradient approximation (GGA). The results show that the remaining silicides have stable structures except that W3Si is a metastable structure in X3Si compounds. Based on the stress-strain theory, the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of Cr3Si and Mo3Si were estimated by Voigt-Reuss-Hill method: 248.7 GPa, 158.9 GPa, 393.0 GPa, 0.24 and 249.2 GPa, 134.6 GPa, 342.1 GPa, 0.27. According to the state density (DOS) analysis, we can see that the valence band of X3Si compound is a combination of covalent bond and metal bond. The temperature of Debye of Cr3Si (645.1 K) in X3Si compound is the highest. The hardness of these silicon compounds is evaluated using a semi empirical hardness theory and the result shows that Cr3Si (10.96 GPa) is the hardest compound among them.

scholarly journals Photochemistry of 1-Phenyl-4-Allyl-Tetrazol-5-One: A Theoretical Study Contribution towards Mechanism Elucidation

2021 ◽  
Vol 11 (9) ◽  
pp. 4045
Author(s):  
Amilcar Duque-Prata ◽  
Carlos Serpa ◽  
Pedro J. S. B. Caridade
Keyword(s):  
Density Functional ◽  
Reaction Pathway ◽  
Intramolecular Proton Transfer ◽  
Polarizable Continuum Model ◽  
Uv Spectra ◽  
Point Of View ◽  
Basis Set ◽  
Pathway Evolution ◽  
Photodegradation Mechanism ◽  
Energetic Point

The photodegradation mechanism of 1-phenyl-4-allyl-tetrazol-5-one has been studied using (time-dependent) density functional theory with the M06-HF, B3LYP, and PBE0 functionals and the VDZ basis set. All calculations have been carried out using the polarizable continuum model to simulate the solvent effects of methanol. The reaction pathway evolution on the triplet state has been characterised to validate a previously postulated experimental-based mechanism. The transition states and minimums have been initially located by local scanning in partial constrained optimisation, followed by a fully relaxed search procedure. The UV spectra has shown to be better described with PBE0 functional when compared with the experimental results, having the M06-HF a shift of 40 nm. From the energetic point of view, the postulated mechanism has been validated in this work showing a concerted photoextrusion of the N2 molecule. The intramolecular proton transfer occurs at a later stage of the mechanism after cyclization of the allyl group on a triplet biradical intermediate. The photoproduct observed experimentally, a pyrimidinone, has been characterised. The infrared spectroscopic reaction profile has also been proposed.

Germanene: a new electronic gas sensing material

RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 102264-102271 ◽  
Author(s):  
Sanjeev K. Gupta ◽  
Deobrat Singh ◽  
Kaptansinh Rajput ◽  
Yogesh Sonvane
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Electronic Properties ◽  
Structural Stability ◽  
Density Functional ◽  
Gas Sensing ◽  
Functional Theory ◽  
Adsorption Characteristics ◽  
Sensing Material ◽  
Gas Molecules

The structural stability and electronic properties of the adsorption characteristics of several toxic gas molecules (NH3, SO2 and NO2) on a germanene monolayer were investigated using density functional theory (DFT) based on an ab initio method.

Structural, Elastic and Electronic Properties of γ˝ Phase Precipitate in Mg-Gd-Zn Alloy

2019 ◽  
Vol 41 (6) ◽  
pp. 932-932
Author(s):  
Mengmeng Wu Mengmeng Wu ◽  
Rongkai Pan Rongkai Pan ◽  
Jilei Liang Jilei Liang ◽  
Guohai Zhou Guohai Zhou ◽  
Li Ma and Chunyu Zhang Li Ma and Chunyu Zhang
Keyword(s):  
Density Functional ◽  
Elastic Anisotropy ◽  
Poisson Ratio ◽  
Covalent Bond ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Functional Theory ◽  
Full Relaxation ◽  
Principle Density Functional Theory ◽  
Zn Alloy

The γ˝ phase (Mg4GdZn) precipitate in Mg-Gd-Zn alloy was calculated via first-principle density functional theory within the generalized gradient approximation. Through structure optimization of full relaxation, the lattice parameters were theoretically obtained, and the calculated Mg4GdZn is the most energetically stable in view of the formation energy. Independent elastic constants were also calculated, illustrating the calculated Mg4GdZn is mechanically stable. The shear modulus, polycrystalline bulk modulus, Poisson ratio, and Young’s modulus of Mg4GdZn were calculated via the Voigt-Reuss-Hill approximation. Elastic anisotropy and ductility were analyzed in details. Seen from their charge density distribution and electronic density of states, both metallic bond and covalent bond were found in Mg4GdZn.

Structural, electronic, and mechanical properties of anatase titanium dioxide

2019 ◽  
Vol 15 (2) ◽  
pp. 306-316 ◽  
Author(s):  
Debashish Dash ◽  
Chandan Kumar Pandey ◽  
Saurabh Chaudhary ◽  
Susanta Kumar Tripathy
Keyword(s):  
Mechanical Properties ◽  
Titanium Dioxide ◽  
Electronic Properties ◽  
Density Functional ◽  
Paper Industry ◽  
Ground Level ◽  
Basis Set ◽  
Indirect Transition ◽  
Content Type ◽  
Valence Region

PurposeThe purpose of this paper is to analyze various properties of anatase titanium dioxide (TiO2) nanoparticles. Further, it proposes to implement Linear Combinations of Atomic Orbitals (LCAO) basis set under the framework of density functional theory and outline how LCAO is able to provide improved results in terms of various mechanical properties rather than plane wave and other theoretical results.Design/methodology/approachThis paper provides an exploratory study on anatase TiO2by implementing OLCAO–DFT–LDA–LBFGS–EOS–PZ algorithms to find out various ground-level properties. The data so obtained are complemented by various analysis using mathematical expressions, description of internal processes occurred and comparison to others’ analytical results.FindingsThe paper provides some empirical insights on how mechanical properties of anatase TiO2improved by implementing LCAO methodology. From the analysis of electronic properties, it is seen that the anatase TiO2supports the inter band indirect transition from O-2p in valence region to Ti-3d in the conduction region.Research limitations/implicationsMost of the electronic properties are underestimated because a single exchange-correlation potential is not continuous across the gap. This gap can be enhanced by implementing Green’s function in place of DFT and the other way is to implement self-interaction correction.Practical implicationsThe use of anatase TiO2is primarily used for catalytic applications. This is also used to enhance the quality of paper in the paper industry. Additionally, this is used as a prime ingredient in cosmetic industry.Originality/valueThis paper fulfills an identified need to study how LCAO, another basis set, plays an important role in improving material properties.

Structural, Thermodynamic, Elastic, and Electronic Properties of α-SnS at High Pressure from First-Principles Investigations

2015 ◽  
Vol 70 (11) ◽  
pp. 949-960 ◽  
Author(s):  
Chun Mei Liu ◽  
Chao Xu ◽  
Man Yi Duan
Keyword(s):  
Experimental Data ◽  
Electronic Properties ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Energy Relation ◽  
Potential Density ◽  
Functional Theory ◽  
Free Energy Relation ◽  
Similar Growth ◽  
Pseudo Potential

AbstractSnS has potential technical applications, but many of its properties are still not well studied. In this work, the structural, thermodynamic, elastic, and electronic properties of α-SnS have been investigated by the plane wave pseudo-potential density functional theory with the framework of generalised gradient approximation. The calculated pressure-dependent lattice parameters agree well with the available experimental data. Our thermodynamic properties of α-SnS, including heat capacity CP , entropy S, and Gibbs free energy relation of –(GT –H0) curves, show similar growth trends as the experimental data. At T=298.15 K, our CP =52.31 J/mol·K, S=78.93 J/mol·K, and –(GT –H0)=12.03 J/mol all agree very well with experimental data CP =48.77 J/mol·K and 49.25 J/mol·K, S=76.78 J/mol·K, and –(GT –H0)=12.38 J/mol. The elastic constants, together with other elastic properties, are also computed. The anisotropy analyses indicate obvious elastic anisotropy for α-SnS along different symmetry planes and axes. Moreover, calculations demonstrate that α-SnS is an indirect gap semiconductor, and it transforms to semimetal with pressure increasing up to 10.2 GPa. Combined with the density of states, the characters of the band structure have been analysed in detail.

Feasibility study of hydrogen-bonded nucleic acid base pairs in gas and water phases — A theoretical study

2011 ◽  
Vol 89 (11) ◽  
pp. 1403-1409 ◽  
Author(s):  
S. Arshadi ◽  
A.R. Bekhradnia ◽  
A. Ebrahimnejad
Keyword(s):  
Hydrogen Bonding ◽  
Nucleic Acid ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Biological Properties ◽  
Point Of View ◽  
Basis Set ◽  
Base Pairs ◽  
Bonding Properties ◽  
Energetic Point

To investigate the base pair binding probabilities for nucleic acid bases, numerous models were studied for contacts between adenine, thymine, guanine, cytosine, and uracil using density functional theory (DFT) in combination with the 6–311G* basis set. We obtained an assessment for the energy given by our calculations in gas and aqueous phases, which showed that it should be incorporated into hydrogen bonding and propeller rotational energies. The 42 complexes of base pairs (5 regular and 37 irregular base pairs) were proposed and their hydrogen-bonding (H-bonding) properties were verified. The hydrogen bonds in some irregular base pairs, including CC, UU, and TT (series 1), were stronger than in regular GC and AT base pairs. Also, the strength of the hydrogen bonds in the proposed base pairs, including CU, GG, GU, and TU (series 2), were similar to regular base pairs from an energetic point of view. The propeller rotations revealed a higher rotational barrier energy (6–7.5 kcal/mol; 1 cal = 4.184 J) for irregular base pairs (series 1 and 2) than regular GC and AT ones (1–3 kcal/mol). Nevertheless, the trend in these affinities of the complex contact probabilities and their biological properties were confirmed by our calculations.

Structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) intermetallic compounds and their hydrides: An ab initio study

2014 ◽  
Vol 28 (17) ◽  
pp. 1450105 ◽  
Author(s):  
Reza Sarhaddi ◽  
Hadi Arabi ◽  
Faiz Pourarian
Keyword(s):  
Electronic Properties ◽  
Intermetallic Compounds ◽  
Enthalpy Of Formation ◽  
Structural Stability ◽  
Electronic Structures ◽  
Density Functional ◽  
Site Preference ◽  
Hydrogen Atoms ◽  
The Stability ◽  
The Enthalpy Of Formation

The structural, stability and electronic properties of C15- AB 2 ( A = Ti , Zr ; B = Cr ) isomeric intermetallic compounds were systematically investigated by using density functional theory (DFT) and plane-wave pseudo-potential (PW-PP) method. The macroscopic properties including the lattice constant, bulk modulus and stability for these compounds were studied before and after hydrogenation. For parent compounds, the enthalpy of formation was evaluated with regard to their bulk modules and electronic structures. After hydrogenation of compounds at different interstitial tetrahedral sites ( A 2 B 2, A 1 B 3, B 4), a volume expansion was found for hydrides. The stability properties of hydrides characterized the A 2 B 2 sites as the site preference of hydrogen atoms for both compounds. The Miedema's "reverse stability" rule is also satisfied in these compounds as lower the enthalpy of formation for the host compound, the more stable the hydride. Analysis of microscopic properties (electronic structures) after hydrogenation at more stable interstitial site ( A 2 B 2) shows that the H atoms interact stronger with the weaker (or non) hydride forming element B   (Cr) than the hydride forming element A  ( Ti/Zr ). A correlation was also found between the stability of the hydrides and their electronic structure: the deeper the hydrogen band, the less stable the hydride.

Sign in / Sign up

Export Citation Format

Share Document