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R. D. Eithiraj

Bio: R. D. Eithiraj is an academic researcher from VIT University. The author has contributed to research in topics: Lattice constant & Ground state. The author has an hindex of 7, co-authored 18 publications receiving 212 citations. Previous affiliations of R. D. Eithiraj include Guangdong University of Technology & Anna University.

Papers
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TL;DR: In this article, first principles were performed to investigate the electronic structure and ground-state properties of alkali-metal sulfides using the tight-binding linear muffin-tin orbital (TB-LMTO) method.
Abstract: First-principles calculations have been performed to investigate the electronic structure and ground-state properties of alkali-metal sulfides Li2S, Na2S, K2S and Rb2S using the tight-binding linear muffin-tin orbital (TB-LMTO) method. At ambient conditions these compounds are found to crystallize in the cubic antifluorite (anti-CaF2-type) structure. The exchange correlation energy is described in the local density approximation (LDA) using the von-Barth and Hedin parameterization scheme. The calculated ground-state properties of these compounds such as equilibrium lattice parameter and bulk modulus are in agreement with the other theoretical calculations and experiment results. From the results of the electronic-structure calculations, we find that Li2S, K2S and Rb2S are indirect bandgap semiconductors, whereas Na2S is found to be a direct bandgap semiconductor. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

59 citations

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TL;DR: In this paper, the first principles tight-binding linear muffin-tin orbital method within the local density approximation (LDA) has been used to calculate the ground-state properties, structural phase stability and pressure dependence of the band gap of NaZnX (X = P, As, Sb).
Abstract: The first-principles tight-binding linear muffin-tin orbital method within the local density approximation (LDA) has been used to calculate the ground-state properties, structural phase stability and pressure dependence of the band gap of NaZnX (X = P, As, Sb). All three compounds are found to crystallize in the tetragonal Cu2Sb-type (C38) structure. NaZnAs is also found to crystallize in the zinc-blende-type related structure, i.e. the MgAgAs (order CaF2)-type structure. By interchanging the position of the atoms in the zinc-blende structure, three phases (α, β and γ) are formed. The energy–volume relations for these compounds have been obtained in the Cu2Sb-type and cubic α, β and γ phases of the zinc-blende-type related structure. Under ambient conditions these compounds are more stable in the Cu2Sb-type structure and are in agreement with experimental observations. At high pressure, these compounds undergo a structural phase transition from the tetragonal Cu2Sb-type to cubic α (or β) phase, and the transition pressures were calculated. The equilibrium lattice parameter, bulk modulus and the cohesive energy for these compounds have also been calculated and are compared with the available results. In the Cu2Sb-type structure, NaZnP is found to be a direct-band-gap semiconductor, NaZnAs shows a very small direct band gap and NaZnSb is found to be a metal. In the α and β phases, NaZnP is found to be a direct-band-gap semiconductor, whereas NaZnAs and NaZnSb are found to be semi-metallic. In the γ-phase, all three compounds are found to exhibit metallic behaviour. However, this phase is energetically unfavourable.

31 citations

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TL;DR: In this article, self-consistent scalar-relativistic band structure calculations have been performed to investigate the electronic structure and groundstate properties of alkali-metal oxides Li2O, Na2O and Rb2O in cubic antifluorite structure using the linear muffin-tin orbital in its tight-binding representation (TB-LMTO) method.
Abstract: Self-consistent scalar-relativistic band structure calculations have been performed to investigate the electronic structure and groundstate properties of alkali-metal oxides Li2O, Na2O, K2O and Rb2O in cubic antifluorite (anti-CaF2-type) structure using the linear muffin-tin orbital in its tight-binding representation (TB-LMTO) method. The calculated ground-state properties of these compounds such as equilibrium lattice parameter and bulk modulus are in agreement with the other theoretical calculations and experimental results. The results of the electronic structure calculations show that Li2O, K2O and Rb2O are indirect band gap semiconductors, whereas Na2O is found to be a direct band gap semiconductor. r 2007 Elsevier B.V. All rights reserved.

28 citations

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TL;DR: In this paper, the magnetic and electronic properties of WC-, MnP-, NaCl- and zinc blende (ZB)-type Mo and W based group V compounds, TMX (TM=Mo and W; X = N, P, As, Sb and Bi), using the tight-binding linear muffin-tin orbital (TB-LMTO) method, were analyzed.

26 citations

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TL;DR: In this article, a combined experimental and theoretical study of the local chemistry of cerium oxide films and islands on Ru(0001) is presented based on intensityvoltage low-energy electron microscopy [$I(V)$-LEEM] and resonant x-ray photoemission spectroscopy.
Abstract: A combined experimental and theoretical study of the local chemistry of cerium oxide films and islands on Ru(0001) is presented. Based on intensity-voltage low-energy electron microscopy [$I(V)$-LEEM] and resonant x-ray photoemission spectroscopy, we establish a one-to-one correspondence between the local oxidation state of ${\mathrm{Ce}}^{3+}$ [cubic Ce${}_{2}$O${}_{3}$(111)] and ${\mathrm{Ce}}^{4+}$ [cubic CeO${}_{2}$(111)] and their respective spatially resolved $I(V)$ curves. Ab initio scattering theory explains the difference between the $I(V)$ curves in the low-energy range in terms of the ${k}_{\ensuremath{\parallel}}=0$ projected band structure arising from the different structure of the Ce 5d states in fully oxidized and reduced ceria. The theoretical analysis unambiguously attributes the LEEM contrast observed for chemically reduced cerium oxide to a variation in oxidation state on the nanometer scale, which is not present for the as-grown islands.

22 citations


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TL;DR: Based on advanced first-principles calculations, this paper found that nitrogen is actually a deep acceptor, with an exceedingly high ionization energy of 1.3 eV, and hence cannot lead to hole conductivity in ZnO.
Abstract: Based on electronic structure and atomic size considerations, nitrogen has been regarded as the most suitable impurity for p-type doping in ZnO. However, numerous experimental efforts by many different groups have not resulted in stable and reproducible p-type material, casting doubt on the efficacy of nitrogen as a shallow acceptor. Based on advanced first-principles calculations we find that nitrogen is actually a deep acceptor, with an exceedingly high ionization energy of 1.3 eV, and hence cannot lead to hole conductivity in ZnO. In light of this result, we reexamine prior experiments on nitrogen doping of ZnO.

315 citations

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TL;DR: Several studies with model ceria catalysts have shown the importance of strong metal-support interactions and a substantial body of knowledge has been acquired and concepts have been developed for a more rational approach to the design of novel technical catalysts containing ceria.
Abstract: Model metal/ceria and ceria/metal catalysts have been shown to be excellent systems for studying fundamental phenomena linked to the operation of technical catalysts. In the last fifteen years, many combinations of well-defined systems involving different kinds of metals and ceria have been prepared and characterized using the modern techniques of surface science. So far most of the catalytic studies have been centered on a few reactions: CO oxidation, the hydrogenation of CO2, and the production of hydrogen through the water–gas shift reaction and the reforming of methane or alcohols. Using model catalysts it has been possible to examine in detail correlations between the structural, electronic and catalytic properties of ceria–metal interfaces. In situ techniques (X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, infrared spectroscopy, scanning tunneling microscopy) have been combined to study the morphological changes under reaction conditions and investigate the evolution of active phases involved in the cleavage of C–O, C–H and C–C bonds. Several studies with model ceria catalysts have shown the importance of strong metal–support interactions. In general, a substantial body of knowledge has been acquired and concepts have been developed for a more rational approach to the design of novel technical catalysts containing ceria.

285 citations

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TL;DR: In this article, the authors examined the potential and the challenges of designing an ultrathin reverse osmosis (RO) membrane from graphene, focusing on the role of computational methods in designing, understanding, and optimizing the relationship between atomic structure and RO performance.

206 citations

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TL;DR: It is suggested that the oxygen vacancies and their defect states provide hopping channels, which are comparable to experimental observations and could be responsible for hole conduction in the "leaky" TiO2 recently discovered for the photochemical water-splitting applications.
Abstract: The amorphous titanium dioxide (a-TiO2) has drawn attention recently due to the finding that it holds promise for coating conventional photoelectrodes for corrosion protection while still allowing the holes to transport to the surface. The mechanism of hole conductivity at a level much higher than the edge of the valence band is still a mystery. In this work, an amorphous TiO2 model is obtained from molecular dynamics employing the "melt-and-quench" technique. The electronic properties, polaronic states and the hole conduction mechanism in amorphous structure were investigated by means of density functional theory with Hubbard's energy correction (DFT + U) and compared to those in crystalline (rutile) TiO2. The formation energy of the oxygen vacancy was found to reduce significantly (by a few eV) upon amorphization. Our theoretical study suggested that the oxygen vacancies and their defect states provide hopping channels, which are comparable to experimental observations and could be responsible for hole conduction in the "leaky" TiO2 recently discovered for the photochemical water-splitting applications.

185 citations

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TL;DR: In this paper, nanocomposites of selenium (Se) and ordered mesoporous silicon carbide-derived carbon (OM-SiC-CDC) were used as cathodes for lithium-selenium (Li-Se) batteries.
Abstract: Nanocomposites of selenium (Se) and ordered mesoporous silicon carbide-derived carbon (OM-SiC-CDC) are prepared for the first time and studied as cathodes for lithium-selenium (Li-Se) batteries. The higher concentration of Li salt in the electrolytes greatly improves Se utilization and cell cycle stability. Se-CDC shows significantly better performance characteristics than Se-activated carbon nanocomposites with similar physical properties. Se-CDC also exhibits better rate performance and cycle stability compared to similarly produced sulfur (S)–CDC for Li/S batteries.

143 citations