First-principles study of intermetallic compounds In CrMnFeCoNiZr system high-entropy alloy

Conversion of carbon-di-oxide into selective hydrocarbon using stable catalyst remains a holy-grail in catalysis community. The high overpotential, stability, and selectivity in use of a single metal-based catalyst still remain a challenge. In current work, instead of using pure noble metals (Ag, Au, and Pt) as the catalyst, a novel nanocrystalline high entropy alloy (HEA: AuAgPtPdCu) has been used for conversion of CO2 into gaseous hydrocarbons. Utilizing an approach of multi-metallic HEA, a Faradaic efficiency of about 100% towards gaseous products is obtained. The reason behind the superior catalytic activity of high entropy alloy (HEA) was established through first-principles based density functional theory (DFT) by comparing it with pristine Cu (111) surface. This is attributed to the reversal in adsorption trends for two out of the total eight intermediates - *OCH3 and *O on Cu(111) and HEA surfaces.

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Nobel Metal Based High Entropy Alloy for Conversion of Carbon Dioxide (CO2) to Hydrocarbon

10.26434/chemrxiv.9777218 ◽

2019 ◽

Author(s):

Subramanian Nellaiappan ◽

Nirmal Kumar ◽

Ritesh Kumar ◽

Arko Parui ◽

Kirtiman Deo Malviya ◽

...

Keyword(s):

First Principles ◽

Density Functional ◽

Noble Metals ◽

High Entropy Alloy ◽

Functional Theory ◽

Faradaic Efficiency ◽

High Entropy ◽

Gaseous Products ◽

Gaseous Hydrocarbons ◽

Carbon Dioxide Co2

Conversion of carbon-di-oxide into selective hydrocarbon using stable catalyst remains a holy-grail in catalysis community. The high overpotential, stability, and selectivity in use of a single metal-based catalyst still remain a challenge. In current work, instead of using pure noble metals (Ag, Au, and Pt) as the catalyst, a novel nanocrystalline high entropy alloy (HEA: AuAgPtPdCu) has been used for conversion of CO2 into gaseous hydrocarbons. Utilizing an approach of multi-metallic HEA, a Faradaic efficiency of about 100% towards gaseous products is obtained. The reason behind the superior catalytic activity of high entropy alloy (HEA) was established through first-principles based density functional theory (DFT) by comparing it with pristine Cu (111) surface. This is attributed to the reversal in adsorption trends for two out of the total eight intermediates - *OCH3 and *O on Cu(111) and HEA surfaces.

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Energetics and Structural Investigation of Double-Walled Carbon and Silicon Nanotubes

MRS Proceedings ◽

10.1557/proc-633-a13.41 ◽

2000 ◽

Vol 633 ◽

Author(s):

Solange B. Fagan ◽

Daniela S. Sartor ◽

R. Mota ◽

R. J. Baierle ◽

Antônio J. R. da Silva ◽

...

Keyword(s):

Density Functional Theory ◽

Monte Carlo ◽

First Principles ◽

Density Functional ◽

Structural Investigation ◽

First Principles Calculations ◽

Functional Theory ◽

Empirical Potential ◽

Silicon Nanotubes ◽

Cohesive Energies

AbstractUsing two different approaches: Monte Carlo simulations with Tersoff empirical potential and first principles calculations, the energetics and the structural properties of double-walled carbon and silicon nanotubes are investigated. Through Tersoff potential, the changes on cohesive energies for the Si and C systems are determined for several outer tubules for a fixed inner tube. Adopting first principles calculations, based on density functional theory, the trends, in terms of the cohesive energies, are compared with the corresponding obtained results using Tersoff empirical potential. The structures, specially of the most stable double-walled nanotubes, are discussed.

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Hydrogen Isotopic Effects of Uranium Hydrides: First-Principles Calculations

Materials Science Forum ◽

10.4028/www.scientific.net/msf.817.675 ◽

2015 ◽

Vol 817 ◽

pp. 675-684 ◽

Cited By ~ 1

Author(s):

Hai Yan Lu

Keyword(s):

Raman Spectrum ◽

First Principles ◽

Density Functional ◽

Coulomb Repulsion ◽

Local Spin Density Approximation ◽

Functional Theory ◽

Lattice Constants ◽

Isotopic Effects ◽

Typical Frequency ◽

Good Agreement

In this paper, we study the ground-state and lattice dynamical properties of β-UH--3by means of the first-principles density functional theory within the local spin-density approximation (LSDA)+Uformulism. The lattice constants and electronic structure are correctly described by taking into account the strong on-site Coulomb repulsion among the 5felectrons localized on uranium atoms. Good agreement with experiments is achieved by tuning the effective Hubbard parameter at around 4 eV. The phonon band structure confirms the dynamical stability of β-UH--3, and the Raman-active modes are consistent with Raman spectrum measurements. The substitution of the deuterium (tritium) atom for hydrogen atom makes significant variations in the typical frequency of Raman-active modes. It is found that the Raman-active mode frequency is approximately inversely proportional to the square root of the hydrogen isotope mass. We conclude that Raman spectrum provides a powerful method for detecting hydrogen isotopic effects.

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First-principles study on electronic, optic, elastic, dynamic and thermodynamic properties of RbH compound

International Journal for Simulation and Multidisciplinary Design Optimization ◽

10.1051/smdo/2015006 ◽

2015 ◽

Vol 6 ◽

pp. A6 ◽

Cited By ~ 5

Author(s):

Sinem Erden Gulebaglan ◽

Emel Kilit Dogan ◽

Mehmet Nurullah Secuk ◽

Murat Aycibin ◽

Bahattin Erdinc ◽

...

Keyword(s):

Thermodynamic Properties ◽

Band Gap ◽

Lattice Constant ◽

First Principles ◽

Density Functional ◽

Temperature Dependent ◽

Functional Theory ◽

Salt Structure ◽

Elastic Lattice ◽

Good Agreement

We performed first-principles calculations to obtain the electronic, optical, elastic, lattice-dynamical and thermodynamic properties of RbH compound with rock salt structure. The ground-state properties, i.e., the lattice constant and the band gap were investigated using a plane wave pseudopotential method within density functional theory. The calculated lattice constant, bulk modulus, energy band gap and elastic constants are reported and compared with previous theoretical and experimental results. Our calculated results and the previous results which are obtained from literature are in a good agreement. Moreover, real and imaginary parts of complex dielectric function, reflectivity spectrum, absorption, extinction coefficient and loss function as a function of photon energy and refractive index with respect to photon wavelength were calculated. In addition, temperature dependent thermodynamic properties such as Helmholtz free energy, internal energy, entropy and specific heat have been studied.

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Atomistic Simulation and Density Functional Analysis of Ni(111)-ZrO2(100)(Cubic) and NiO(111)-Ni(111)-ZrO2(100)(Cubic) Interfaces

MRS Proceedings ◽

10.1557/proc-654-aa4.5.1 ◽

2000 ◽

Vol 654 ◽

Cited By ~ 3

Author(s):

Chang-Xin Guo ◽

Donald E. Ellis ◽

Vinayak P. Dravid ◽

Luke Brewer

Keyword(s):

First Principles ◽

Atomistic Simulation ◽

Density Functional ◽

Depth Profiling ◽

Interface Plane ◽

Functional Theory ◽

Spatially Resolved ◽

Microscopy Data ◽

Energy Profiling ◽

Good Agreement

AbstractThe atomic arrangement and electronic structure in the vicinity of Ni(111)- ZrO2(100)(Cubic) and NiO(111)-Ni(111)-ZrO2(100)(Cubic) interfaces have been studied by atomistic simulation and by first-principles Density Functional theory. “Depth Profiling” is carred out in both methodologies, to determine modifications of cohesive energy and electron distribution of atomic layers from the interface plane. The energy profiling results show the interface consists of only a few atomic layers. Simulation results and electron density analyses are in good agreement with High Resolution Spatially Resolved Electron Microscopy data.

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Study on Electronic and Optical Properties of Al-Doped ZnS from Density Function Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.734-737.2405 ◽

2013 ◽

Vol 734-737 ◽

pp. 2405-2410 ◽

Cited By ~ 1

Author(s):

Ai Ling Wu ◽

Li Guan ◽

Ting Kun Gu ◽

Pei Yuan Feng

Keyword(s):

Optical Properties ◽

Absorption Spectra ◽

Density Functional ◽

Systematic Investigation ◽

Al Doping ◽

Functional Theory ◽

Electronic And Optical Properties ◽

Calculation Results ◽

Plane Wave Approximation ◽

Good Agreement

Using ab-initio ultrasoft pseudopotential plane wave approximation method based on density functional theory (DFT), a systematic investigation on electronic and optical properties of ZnS with and without Al-doping has been performed. Calculation results show that Al-doping narrows the band gap of ZnS systems and Al-doped ZnS system changes from semiconductor into metal through the Mott transition. Moreover, with Al-doping increasing, the increase of absorption coefficient and redshift of absorption spectra are obtained. Absorption spectra of pure ZnS and Al-doped ZnS are in good agreement with the experimental results.

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Composition and Strain Dependence of the Piezoelectric Coefficients in Semiconductor Alloys

MRS Proceedings ◽

10.1557/proc-1017-dd04-11 ◽

2007 ◽

Vol 1017 ◽

Author(s):

T. Hammerschmidt ◽

M. A. Migliorato ◽

D. Powell ◽

A. G. Cullis ◽

G. P. Srivastava

Keyword(s):

First Principles ◽

Density Functional ◽

Piezoelectric Coefficient ◽

Tight Binding ◽

Tight Binding Model ◽

Semiconductor Alloys ◽

Binding Model ◽

Functional Theory ◽

Photo Current ◽

Good Agreement

AbstractWe propose a tight-binding model for the polarization that considers direct and dipole contributions and employs microscopic quantities that can be calculated by first-principles methods, e.g. by employing Density Functional Theory (DFT). Applying our model to InxGa1-xAs alloys allows us to settle discrepancies between the values of e14 as obtained from experiments and from linear interpolations between the values of InAs and GaAs. Our calculated piezoelectric coefficient is in very good agreement with photo current measurements of InAs/GaAs(111) quantum well samples.

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Solid State and Electronic Structure of Rare Earth Metal Intercalated Graphite from First-principles Theory

Zeitschrift für Naturforschung B ◽

10.1515/znb-2007-0715 ◽

2007 ◽

Vol 62 (7) ◽

pp. 971-976 ◽

Cited By ~ 5

Author(s):

Chang-Ming Fang ◽

Joseph Bauer ◽

Jean-Yves Saillard ◽

Jean-Francois Halet

Keyword(s):

Rare Earth ◽

First Principles ◽

Density Functional ◽

Rare Earth Metals ◽

Earth Metal ◽

Generalized Gradient ◽

Functional Theory ◽

Intercalated Graphite ◽

Generalized Gradient Approximation ◽

Cohesive Energies

Abstract The structural arrangements of the graphite intercalates LnC6 (Ln = La, Ce, Nd and Yb) were investigated using Density Functional Theory (DFT) within the Generalized Gradient Approximation (GGA). The EuC6-type structure (AαAβ AαAβ AαA stacking) is slightly energetically preferred for La and Ce, whereas with the other rare earth metals almost the same cohesive energies are found for the three different atomic arrangements AαAαAαAαAαA. . ., AαAβ AαAβ AαA. . ., and AαAβ AγAαAβ A. . . A rather important charge transfer occurs from the metals to the carbon sheets, with the electrons partially occupying the bottom of the carbon π* band. As a consequence, a lengthening of the C-C bond lengths of ca. 0.02 Å is computed with respect to the C-C bonds in graphite. Two-dimensional metallic character is expected for LaC6 according to its band structure.

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