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To overcome environmental problems and the energy crisis, water splitting through solar energy for the production of hydrogen fuel is a promising technique. Efficient and low-cost photocatalyst are highly desired. In the recent era, van der Waal (vdW) heterostructures have gained considerable attention due to their promising properties. Hybrid density functional theory is used to calculate the electronic and photocatalytic properties of BX-MSSe (X = P, As and M = Mo, W) vdW heterostructures. Most stable stacking is figured out among different stacking from their relaxation energy. The stability of the stable stacking is confirmed through phonon calculations. Calculated band structure shows that BAs-MoSSe and BP-WSSe have direct band gap nature while the BP-MoSSe and BAs-WSSe have indirect band gap nature. BAs-MoSSe has Type-I band alignment while BP-MoSSe, BAs-WSSe and BP-WSSe have type-II band alignment. The creation of heterostructures broadened the optical absorption from the infrared to the ultraviolet region of the solar spectrum. To tune the properties of these heterostructures compressive and tensile strain is applied. Switching in band alignment is predicted in these heterostructures with the applications of strain. Based on valence and conduction band edges potentially the photocatalytic behavior for pH = 0 is investigated, which confirms that in unstrained conditions BP-MSSe (M = Mo, W) heterostructures are efficient photocatalyst. [ABSTRACT FROM AUTHOR]

In this paper, the structural, elastic, and electronic properties of RIn3 and RSn3 (R = Sm, Eu, Gd) compounds have been investigated using the full potential linearized augmented plane wave plus local orbital method within the density functional theory. The structural properties are investigated using the LDA, GGA, and the band correlated LDA+U and GGA+U schemes. The lattice parameters are in good agreement with the available experimental results and the divalent state of Eu is also verified. The spin-orbit coupling is included in order to predict the correct electronic properties and splitting of 4f states of the rare earth elements is also incorporated. We calculated Bulk modulus, shear modulus, Young's modulus, anisotropic ratio, Kleinman parameters, Poisson's ratio, Lame's co-efficient, sound velocities for shear and longitudinal waves, and Debye temperature. We also predict the Cauchy pressure and B/G ratio in order to explore the ductile and brittle behaviors of these compounds. [ABSTRACT FROM AUTHOR]

• P-doped fullerene selectively removed CO 2 from N 2 /CO 2 mixture. • CO 2 physisorbed in the absence of electric field. • Applied electric field transforms physisorption to chemisorption. • CO 2 is easily recovered by removing electric field. In this work adsorption of CO 2 on P-doped fullerene is explored through density functional theory in the presence and absence of an electric field. The calculated adsorption energy reveals physisorption in the absence of electric field, which changes to chemisorption by the application of field. Hence, adsorbent can be recovered easily for reuse by removing the electric field. It is further revealed that P-doped fullerene is an ideal adsorbent for the removal of CO 2 from the N 2 /CO 2 mixture. [ABSTRACT FROM AUTHOR]

In this theoretical study we investigate the electronic, optical, and photocatalytic properties of monolayer titanium dioxide (TiO2), nickel dioxide (NiO2), and germanium dioxide (GeO2), as well as the effects of strain and stacking on these monolayers. The first principle calculations were performed using density functional theory (DFT) to determine the band structure, density of states, and optical properties of the monolayers. The photocatalytic activity of the monolayers was evaluated based on the water-splitting reaction. The results showed that the electronic and optical properties of the monolayers were significantly affected by strain and stacking. Specifically, the bandgap of TiO2, NiO2, and GeO2 decreased under tensile strain, while it increased under compressive strain. Furthermore, the stacking order of the monolayers affected their electronic and optical properties. The photocatalytic activity of the monolayers was found to be highest for TiO2. This study provides a valuable insight into the properties of monolayer oxides TiO2 and GeO2 and their van der Waal heterostructure GeO2–TiO2 as a potential candidate for photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

The structural, mechanical and vibrational properties of Ru2TiZ (Z = Si, Ge, Sn) Full Heusler Alloys (FHAs) are computed using PBE-GGA as an exchange-correlation functional in Kohn–Sham equations. The calculated lattice constants of these alloys in L21 phase deviate from experimental values upto 0.85 % which shows a good agreement between the model and the experiments. These lattice constants are then used to compute the second order elastic constants C11, C12 and C44 with Wien2k-code. Elastic moduli and mechanical parameters are also calculated by these three independent elastic constants. Mechanical parameters Pugh's and Poisson's ratio indicate non-brittle nature of these alloys. Furthermore, the Debye temperature where the collective vibrations shift to an independent thermal vibration, longitudinal and transverse sound velocities, melting temperatures, and thermal conductivities are also obtained to investigate the phonon modes of oscillation. These phonon modes confirm the stability of these alloys as there exists no imaginary phonon frequency in the phonon-dispersion curves. [ABSTRACT FROM AUTHOR]

We studied the thermo-elastic properties of Ru2Fe Z ( Z=Si, Ge, Sn) Heusler alloys within the framework of density functional theory. Thermo-elastic properties corresponding to elastic modulus, anisotropy, phase stability, elastic wave velocities, thermal stability, Debye temperature, melting temperature, thermal conductivity and formation energy are calculated. The elastic constants C predict the structural and dynamical stabilities while the formation energies show thermal stability of the alloys at 0 K. Pugh's and Poisson's ratios display the ductile nature of alloys. All alloys are anisotropic and we also observed that Ru2FeSn is the hardest material than Ru2FeSi and Ru2FeGe. Moreover, longitudinal mode of vibrations are also observed and are maximum along [100], [110] and [111] directions than the transverse mode of vibrations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive calculation and analysis of defect properties in the corundum, monoclinic, and orthorhombic Ga 2 O 3 phases are presented. • The Ga-rich growth environment in all Ga 2 O 3 phases favors the spontaneous formation of oxygen vacancies with concentrations that can reach as high as 1021 cm−3. • The antisite defects contribution in intrinsic defect density is not negligible in an O-rich environment, and can reach a concentration of 1014 cm−3. • The charge transition levels in all phases are at deep levels within the bandgap. • Raman spectroscopy in an as-grown β-Ga 2 O 3 and a high temperature annealed β-Ga 2 O 3 reveals an increase in point defect concentration, correlating the defect formation energies to experimental observation. Ultrawide bandgap gallium oxide (Ga 2 O 3) is a promising material for power semiconductor devices and deep ultraviolet (UV) solar-blind photodetectors. Understanding the properties of point defects in Ga 2 O 3 is necessary to realize better-performing devices. A comprehensive study based on density functional theory (DFT), using the generalized gradient approximation (GGA): Perdew-Burke-Ernzerhof (PBE) exchange–correlation functional, of point defects in corundum (α), monoclinic (β), and orthorhombic (ε) phases of Ga 2 O 3 is presented. The point defects include vacancies, interstitials, antisites, and extrinsic impurities in various phases of Ga 2 O 3. Defect formation energies, charge transition energy levels, and defect concentrations variation with temperature are listed and presented under both gallium-rich (Ga-rich) and oxygen-rich (O-rich) growth conditions. The formation energy diagrams predict that the Ga 2 O 3 phases favor the formation of Ga and O vacancies and the incorporation of extrinsic impurities. The calculations also show that the charge transition levels are deep inside the bandgap regardless of the Ga 2 O 3 phase and growth environment. The impacts of temperature on the intrinsic point defects are analyzed by probing the vibrational modes of β-Ga 2 O 3 thin films grown in a metal–organic chemical vapor deposition (MOCVD) system at 700 °C temperature and annealed at 1100 °C in an O-rich environment. [ABSTRACT FROM AUTHOR]

In this paper, thermoelectric properties of carbon and nitrogen based twenty metallic antiperovskites MXY 3 (M=Al, Ga, Ir, Mg, Pd, Pt, Rh; X=C, N; Y=Mn, Ni, Sc, Ti, Cr, Fe) using ab-initio density functional theory and post-DFT Boltzmann's techniques are investigated. The electronic properties of these compounds are also discussed. We find high values of Seebeck coefficient and small values of electronic thermal conductivity for AlCTi 3 , AlNSc 3 , AlCNi 3 , AlNTi 3 , GaCCr 3 and MgCNi 3 between −0.25 and 0.25 eV chemical potential. These results show high dimensionless figure of merit in metallic materials and therefore, we predict these materials can be potential candidates for low temperature thermoelectric applications. [ABSTRACT FROM AUTHOR]

In the present study we explore the structural, electronic and thermoelectric properties of IV-VI semiconductors using first principle calculations based on the density functional theory. Generalized gradient approximation (GGA-PBEsol) is used as an exchange-correlation functional for the structural properties of the different crystal phases of these semiconductors. The compounds SnS, SnSe, GeS and GeSe favor orthorhombic structure, lead chalcogenides (PbS, PbSe and PbTe) are stable in the cubic rocksalt structure, while SnS 2 and SnSe 2 exist in hexagonal structure. For band structures additional to GGA, modified Becke and Johnson (mBJ) exchange potential is used. These compounds are narrow band gap semiconductors in the energy range 0.2–2.8 eV. These binary IV-VI chalcogenides have direct band gap nature in cubic crystals while indirect in the orthorhombic phases. The post-DFT (BoltzTraP) calculations are performed to estimate Seebeck coefficient, electric and thermal conductivities, power factor and figure of merit of these compounds to check their applicability in thermoelectric devices. Spin orbit coupling effect influences the electronic and thermoelectric properties of these compounds due to the large size of the constituent elements. Further, the total thermal conductivity is computed using ad-hoc calculation with the experimental results. The calculated values of figure of merit for PbS, PbSe, PbTe and SnTe are in the range 0.68–0.77 at room temperature. [ABSTRACT FROM AUTHOR]

Ternary palladium and platinum oxides NaPd3O4 and NaPt3O4 are studied theoretically using DFT. The calculated structural parameters and geometry are found consistent with the experiments. The mechanical properties analysis show that both compounds are elastically stable; anisotropic and reveal the ductile nature. Electronic cloud explain that the chemical bond between Na and Pd/Pt is ionic, whereas between O and Pd/Pt is covalent. The electronic band structures and densities of states demonstrate that these compounds are metals. The d-state splitting explains the origin of the electronic behaviour of these oxides. The optimised magnetic phase energies and magnetic susceptibility confirm that these oxides are paramagnetic metals. [ABSTRACT FROM AUTHOR]

DFT studies are performed to investigate the structural, mechanical and magneto-electronic properties of the TlTF 3 (T=Fe, Co and Ni) perovskites for the first time using GGA, GGA+U and hybrid density functional theory (HF). Our calculations show that HF give better results than GGA and GGA+U and more consistent with the experiments. The comparison of the lattice constants calculated by HF with experiments shows a maximum underestimation less than 0.2%. The chemical bonding between different ions in these compounds is explained on the bases of electronic clouds, which reveals that in TlFeF 3 , Fe has more ionic character with F than the rest. The mechanical properties explain the hardness of these compounds and show that TlFeF 3 is more ductile. Spin-dependent electronic band profiles show that TlFeF 3 and TlCoF 3 are metallic, whereas TlNiF 3 is pseudo direct wide bandgap semiconductor. The stable magnetic phase optimizations and the calculated magnetic susceptibility confirm that TlFeF 3 and TlNiF 3 are ferromagnetic whereas TlCoF 3 is anti-ferromagnetic material. [ABSTRACT FROM AUTHOR]

In the present density functional studies, structural, mechanical and magneto-electronic properties of CaTaO 3, SrTaO 3 and BaTaO 3 perovskites have been investigated. The calculated structural parameters by DFT and analytical methods are found consistent with the experiments. The analytically calculated tolerance factors of these compounds as well as their mechanical properties show that they are stable in the cubic phase. Furthermore elastic properties show that these materials are ductile in nature and confirm that BaTaO 3 is harder than the rest compounds. The calculated spin dependent magneto-electronic properties reveal the paramagnetic metallic nature of these compounds. The electrical conductivity curve demonstrates significant conductivity above room temperature. On the basis of the presented properties it is expected that these compounds could be efficient electrode materials and need experimental investigations. [ABSTRACT FROM AUTHOR]

Ferromagnetic metallic inverse-perovskite (Eu 3 O)In is studied using hybrid functional theory (HF) in the frame work DFT. The calculated structural parameters and geometries of the material are calculated by different exchange correlation potentials and found that HF results are closed to the experiments. Electronic charge density explains the bond nature and polarization. The spin polarized electronic band profiles and density of states reveal the metallic nature of the compound. The Eu f-state splitting show that the valance bands are dominated mainly by f-[a 2 ], f-[x(T 1 )], f-[y(T 1 )] and f-[z(T 1 )] states. The ground state magnetic phase of the compound is optimized. The optimum energy and magnetic susceptibility confirm the ferromagnetic nature of the compound. On the basis of different properties presented it is predicted that this compound is magnetoresistive material. [ABSTRACT FROM AUTHOR]

In this article we report novel penta-like M 4 P 4 X 2 Y 2 (M = Pd, Pt; X≠Y S, Se, Te) Janus monolayers. The structural stability of the monolayers is double checked by using the phonon spectra and AIMD simulations. After confirming the thermodynamic stability of the monolayers, their structural, mechanical, electronic, and optical properties are systematically explored using the density functional theory (DFT). The calculated results demonstrate indirect bandgap for these monolayers, ranging from 1.57 to 2.58 eV. Furthermore, the photocatalytic investigations show that M 4 P 4 X 2 Y 2 Janus monolayers exhibit the capability of oxidizing H 2 O/O 2 to O 2 , while reducing H+ to H 2. These findings strongly indicate the potential of M 4 P 4 X 2 Y 2 monolayers as photocatalysts for water splitting reaction. [ABSTRACT FROM AUTHOR]

• Nitrous oxide is dissociated over a single Si atom decorated nitrogen doped fullerene • The catalyst shows highly catalytic activity towards CO + O* reaction • The N 2 O + CO reaction is more prominent than CO + O 2 reaction N 2 O have very noxious effects on environment as greenhouse gas in stratosphere and ozone depleting catalyst in lithosphere and CO is a fatal gas. In this study we used spin polarized density functional theory calculations to investigate the possible action of the Si-coordinated nitrogen doped (Si@C 54 N 4) fullerene as potent catalyst for N 2 O reduction and CO oxidation. Our computed results suggest that Si atom is strongly trapped in the N 4 -cavity of the C 54 N 4 with larger negative adsorption energy of -8.06 eV. The N 2 O molecule dissociates into O* and N 2 , where O* remains adsorb over the Si@C 54 N 4 surface. The carbon monoxide on the surface of the catalyst reacts with oxygen forming CO 2 and the energy barrier for the elimination of the adsorbed O* by CO molecule is 0.47 eV. The catalytic reduction of N 2 O and oxidation of CO take place in the presence of O 2 molecule. This process can be used effectively for the mitigation of N 2 O and CO pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

Selective, reversible and tailored adsorption of CO 2 from gas mixture is always demanded to control global warming. We for the first time used P-decorated C 24 N 24 fullerene for selective separation of CO 2 from N 2 /CO 2 mixture in the presence of an electric field by using density functional theory methods. The computed geometrical parameters evince that the binding distances and bond angles (O C O) are remarkably reduced in electric field and that transformed the physisorption to chemisorption by increasing the field from 0.012 to 0.013 au. The adsorption/desorption of CO 2 over the substrate can be easily controlled by switching on and off the electric field. This study reveals that P@C 24 N 24 is a selective adsorbent of CO 2 from N 2 /CO 2 mixture and will help the future synthesis of selective, controllable and regenerable adsorbent for the CO 2 separation from gas mixture in presence of electric field. Image 1 • Adsorption of CO 2 onto P@C 24 N 24 fullerene is explored using DFT calculations. • CO 2 is chemisorbed with the help of electric field. • Adsorbed CO 2 can be easily desorbed by switching off electric field. • P@C 24 N 24 fullerene selectively adsorb CO 2 from N 2 /CO 2 mixture. [ABSTRACT FROM AUTHOR]

In this work porous covalent triazine based frame-work (CTF) is investigated for the removal of emerging pollutants methyl- and propylparaben (MeTP and ProP) using density functional theory approach. Various adsorption configurations of these pollutants over the CTF are evaluated by computing geometrical parameters, adsorption energies (E ad), thermodynamic parameters, total density of states (TDOS), atom in molecule (AIM), natural bonding orbital (NBO), reduced density gradient (RDG) and noncovalent interaction (NCI) analysis. The E ad ranges from −5.92 kcal/mol to −11.70 in gas phase and − 2.50 kcal/mol to −9.57 kcal/mol in solvent phase for MeTP@CTF while −7.04 kcal/mol to −10.23 kcal/mol and − 5.34 kcal/mol to −7.37 kcal/mol is noticed for ProP@CTF, respectively. The negative values of E ad , ∆ H (−3.90 to −9.30 kcal/mol) and Δ G (−2.96 to −8.91 kcal/mol) for all the adsorption configurations confirm the energetic favorable, exothermic and hence spontaneous/feasible nature of the process. The reduction in the energy gap (E gap) shown by TDOS results described the sensitivity of CTF towards the MeTP and ProP. The higher sensitivity of CTF towards both molecules is shown in adsorption configuration 2. The results of AIM, NBO, RDG and NCI analysis are in agreement with the TDOS analysis and confirm that the adsorption occurred through intermolecular hydrogen bonds. These results suggest that CTF can be used as a potent adsorbent for the purification of water from these emerging pollutants. Unlabelled Image • CTF was investigated as adsorbent for emerging pollutants using DFT study • Intermolecular H-bonds are exist between the adsorbent and emerging pollutants • Negative adsorption energies reveals higher adsorption capacity of CTF • Density of states analysis evince the sensitivity of the CTF towards the pollutants [ABSTRACT FROM AUTHOR]

Structural, electronic, magnetic and mechanical properties of the perovskites BiFeO3 (BFO) and BaTiO3 (BTO) are investigated using density functional theory (DFT). Structural and mechanical parameters are calculated using generalized gradient approximation (GGA) and the results consistent with the available literature. The stable magnetic phases are achieved by optimizing total energies versus volumes of the cells in different magnetic configurations such as nonmagnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM). BTO is found to be NM while BFO favors G-type AFM (G-AFM) phase. The electronic properties are investigated using GGA, GGA with Hubbard potential (GGA + U) and modified Becke–Johnson (GGA-mBJ) exchange–correlation functionals. BFO is found to be a direct bandgap semiconductor having gap energy value 3.0 eV whereas BTO is an indirect semiconductor with bandgap energy 2.9 eV. Spin–orbit coupling effect is dominant in BFO due to the larger size of A-site cation. The electrical polarization shows that both the compounds are ferroelectric materials with significant spontaneous polarization of 144.1  μ C/cm2 and 27.9  μ C/cm2 for BFO and BTO respectively. [ABSTRACT FROM AUTHOR]

Magnesium ion batteries (MIBs) are one of the vital strategies for the next-generation energy needs and computational simulations can accelerate this search many folds. In this paper, we suggest a novel cathode material, quinone functionalized hexahydroxytriphenylene (HHTP) and diphenylbutadiynebis (boronic acid) (DPB) based porous polymer (QHHTP-DPB), for Mg-ion batteries. The material is stable with highly porous structure and strong affinities for Mg ions to attach to C=O sites of the quinone rings. The single unit of the polymer layer can be fully loaded with Mg ions at various active sites exhibiting a specific theoretical-capacity of 720.48 mAhg−1 and positive low open-circuit voltage of 0.39 V. No structural variation is observed in QHHTP-DPB and a larger decrease in the HOMO-LUMO gap occurs after Mg ions adsorption onto the polymer, reflecting the better cycling performance and high capacity for Mg ion batteries. These results show that our designed quinone functionalized HHTP-DPB porous polymer could be a futuristic cathode material for MIBs and needs further theoretical and experimental investigations. [Display omitted] • QHHTP-DPB based porous polymer is studied for Mg-ion batteries. • The QHHTP-DPB polymer significantly stored a maximum of 10 Mg ions. • The QHHTP-DPB has high specific capacity of 720.48 mAh/g. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have demonstrated outstanding electronic, optical, and photocatalytic characteristics. In this article, the physical properties of pentagonal-like structure penta-PtPX (X = S, Se, Te) monolayers are systematically investigated by employing density functional theory. Phonon spectra and ab initio molecular dynamics simulations confirmed that these systems are thermodynamically stable. The hybrid HSE06 functional demonstrated that the PtPX monolayers are indirect band gap semiconductors, having band gap of 2.85 eV, 2.69 eV, and 2.14 eV for PtPS, PtPSe, and PtPTe respectively. The optical properties calculated using GW 0 +BSE approach reveal strong anisotropic absorption along x- and y-directions and the optical transitions are dominated by excitons. High absorbance in the visible and ultraviolet light region is observed, and the excitonic peaks are red shifted for heavy chalcogens. Furthermore, the photocatalytic study show that the PtPX monolayers can oxidize H 2 O/O 2 to O 2 and reduce H+ to H 2 , similar to the PdPX (X = S, Se, Te) monolayers. Our results suggest that the PdPX and PtPX (X = S, Se, Te) monolayers have potential for optoelectronic and photovoltaic devices, and are promising photocatalysts for water splitting reaction. [Display omitted] • Square-planar pentagonal structure of penta-PdPS, -PdPSe, -PdPTe, -PtPS, -PtPSe, -PtPTe monolayers. • Electronic and optical properties penta-PtPX and -PdPX (X = S, Se, Te) monolayers. • High visible light absorbance by penta-PtPX and -PdPX (X = S, Se, Te monolayers. • Water splitting ability of penta-PtPX and -PdPX (X = S, Se, Te monolayers. [ABSTRACT FROM AUTHOR]

In this paper, structural, electronic and magnetic properties of the aluminum-rich intermetallic alloy Al13Fe4 are investigated using full potential linearized augmented plane waves (FPLAPW) approach in the frame work of density functional theory (DFT). The calculated structural parameters are consistent with the experimentally reported data. In this alloy, Fe atoms possess different coordination numbers with Al atoms, i.e., Fe(1) and Fe(2) have the same coordination number 5, whereas Fe(3), Fe(4) and Fe(5) have 4, 7 and 9 coordination numbers, respectively. The compound is found metallic and ferromagnetic in nature. Post-DFT (BoltzTraP code) calculations confirm the ferromagnetic and anisotropic behavior. The Fe(5) atom plays a central role in the electronic and magnetic properties of the alloy due to the large coordination with Al atom as compared to the rest Fe atoms. [ABSTRACT FROM AUTHOR]

The structural, magnetic and elastic properties of orthorhombic phase of RAu 2 compounds (R = La, Ce, Pr and Eu) are reported theoretically for the first time using full potential linearized augmented plane waves method within the density functional theory. The structural properties are investigated by treating the exchange and correlation energies with the generalized gradient approximation, PBEsol. Our computed lattice constants are found consistent with the reported experimental results. Our data reveal that they are stable in orthorhombic CeCu 2 type structure. Their mechanical properties such as Young, Shear and bulk moduli, Poisson and anisotropic ratio, Cauchy pressure and B o /G ratio are explored using the PBEsol to evaluate the importance of these compounds in various types of engineering applications. One of the striking features of their mechanical properties is their ductile nature. Magnetically all these intermetallics are antiferromagnetic. [ABSTRACT FROM AUTHOR]

In this paper, we explore the structural, electronic, thermoelectric and elastic properties of intermetallic compounds ScTM (TM = Cu, Ag, Au and Pd) using density functional theory. The produced results show high values of Seebeck coefficients and electrical conductivity for these materials. High power factor for these materials at room-temperature shows that these materials may be beneficial for low-temperature thermoelectric devices and alternative energy sources. Furthermore, elastic properties of these compounds are also calculated, which are used to evaluate their mechanical properties. The Cauchy's pressure and B/ G ratio figure out that these compounds are ductile in nature. The calculated results also predict that these compounds are stable against deforming force. [ABSTRACT FROM AUTHOR]

We have calculated the NMR shielding, structural properties and optoelectronic spectra of XTe 3 O 8 (X = Ti, Zr, Sn and Hf) compounds. The full potential linearized augmented plane wave (FP-LAPW) method and the modified Becke-Johnson (mBJ) are used by density functional theory schemes. The calculated shielding and measured shifts are arranged in a straight line and the tensors of magnetic shielding have a low symmetry and the shielding along the x direction is greater than the y and z directions. Obtained results show that the X ions have the most important influence on the 125 Te chemical shift. Calculated chemical shielding components (σ ii ) decrease from Ti to Sn then increases from Sn to Hf so that these behaviors are vice versa for 125 Te isotropic chemical shift ( δ iso ). Density of states spectra show that the X- p and d states play key role in the optical and NMR calculations. Optical results illustrate that there is a direct relation between the chemical shielding components for Te atom and the static dielectric function, refractive index and Plasmon energies. [ABSTRACT FROM AUTHOR]

The electronical and optical properties of CdGa2S4 under high pressures were studied using the full potential linearized augmented plane wave (FP-LAPW) method within the GGA and mBJ exchange correlation potentials from 0.0 to 16.92 GPa. The obtained results show that the lattice constants, bandgap values, and optoelectronic properties are sensitive to applied external pressures. The mBJ results indicate that the bandgap increases and the static dielectric constants decrease with increasing the pressure. The two none zero dielectric tensor components show considerable anisotropy between the perpendicular and parallel components. The maximum absorption for x direction in all pressures takes place in vacuum UV region. Also, the plasma frequency shifts to the higher energies with increasing the pressure for application in optical devices. The calculated results by mBJ are in close agreement with the experimental values. [ABSTRACT FROM AUTHOR]

In this paper we explore the electronic nature and thermoelectric properties of filled skutterudites AFe 4 Sb 12 (A Ca, Sr and Ba) by DFT and post-DFT techniques. The calculated results show that the filling of Ca, Sr, and Ba at the empty crystal sites enhances the thermoelectric performance of the host material. This increase is a consequence of the coupling between the guest and the host atoms, which affects the electronic density at different symmetry points that increases the density of states of the valence bands. The valence band edge is almost independent of the guest atoms, i.e., the s-bands of Ca, Sr and Ba have negligibly small contribution to the valence band edge. In these compounds, the maximum value of thermoelectric PF/τ of 42.43 × 10 14 μW/cmK 2 s and 33.57 × 10 14 μW/cmK 2 s for the n-type of SrFe 4 Sb 12 in the spin-up and down states respectively. The striking feature of these compounds is their effectiveness at the low chemical potential values for the best thermoelectric performance. [ABSTRACT FROM AUTHOR]

In this article we explore the electronic and magnetic properties of RAu intermetallics (R=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) for the first time. These properties are calculated by using GGA, GGA+ U and hybrid density functional theory (HF) approaches. Our calculations show that HF provides superior results, consistent to the experimentally reported data. The chemical bonding between rare-earth and gold atoms within these compounds are explained on the basis of spin dependent electronic clouds in different planes, which shows predominantly ionic and metallic nature between Au and R atoms. The Cohesive energies of RAu compounds show direct relation with the melting points. Spin-dependent electronic band structure demonstrates that all these compounds are metallic in nature. The magnetic studies show that HoAu and LuAu are stable in non-magnetic structure, PrAu is stable in ferromagnetic phase and CeAu, NdAu, SmAu, GdAu, TbAu, DyAu, ErAu, TmAu, YbAu are anti-ferromagnetic materials. [ABSTRACT FROM AUTHOR]

We have investigated the structural, electronic, magnetic, phononic and thermoelectric properties of rare earth multiferroic manganite RMnO 3 (R = Gd and Tb) compounds by the density functional theory within the spin polarized GGA, LDA and mBJ + U + SOC. The full-potential linearized augmented plane wave and pseudopotential methods are used. The combined mBJ + U + SOC study indicates that the obtained results for the band gap are in close agreement with the experimental results. The Bader analysis show that the ionic nature of the Mn O bonds cause the large charge transfer from Mn to O atoms. Obtained band gaps are different for two spin channels therefore we have calculated the spin polarization dependence of transport properties. The directional thermoelectric study shows that these compounds are anisotropic. We have also presented the phononical properties such as Raman spectra and Born effective charges. [ABSTRACT FROM AUTHOR]

Ternary palladates CaPdO and SrPdO have been studied theoretically using density functional theory approach. The calculated structural properties are consistent with the experimental findings. Mechanical properties show that these compounds are elastically stable, anisotropic and ductile in nature. The electronic properties reveal that they are narrow band gap semiconductors with band gaps 0.12 and 0.10 eV, correspondingly. Both materials are optically active in the infrared ranges of the electromagnetic spectrum. Narrow band gap semiconductors are efficient thermoelectric (TE) materials; therefore, TE properties are also studied and discussed. Furthermore, DFT and post-DFT calculations confirm the paramagnetic nature of these compounds. [ABSTRACT FROM AUTHOR]

In this report, a systematic density functional theory based investigation to explain the character of nitrogen vacancies in structural, electronic and magnetic properties of Ce doped wurtzite AlN is presented. The work demonstrates the modification in the properties of the material upon doping thereby addressing dopant concentration and inter-dopant distance. The presence of anionic vacancy reveals spin polarization and introduction of magnetic character in the structure. The doping produced the magnetic character in the material which was of ferromagnetic nature in most cases except the situation when dopants separated by largest distance of 5.873 Å. The calculated values of total energy and exchange energy suggested the configuration including Ce Al –V N complex is more favorable and exhibits ferromagnetic ordering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Benzoquinone-based microporous polymer is designed as cathode for magnesium-ion batteries that exhibits high stability. • Strong anchoring capability of magnesium ions with polymer have larger binding energies. • The polymer has high storage capacity i.e. twelve Mg ions without any structure distortion/volume change. • The material has high specific capacity of 467.038 mAh/g versus previously reported cathode materials for magnesium-ion batteries. Rechargeable magnesium-ion batteries (MIBs) can fulfill large-scale energy storage needs due to the abundance of Mg but technical challenges due to complexity of its chemistry results uncertainties about their commercialization. We for the first report benzoquinone-based microporous conjugated polymer (BQMCP) as cathode material for MIBs using density functional theory. It is dynamically and thermodynamically stable with a strong affinity for Mg-ions. The Mg ions strongly attaches to the C O group (redox-active sites) than π-bonds of BQMCP. The binding energy demonstrates that the interaction of the 2 Mg-ion system (BE = −47.32 kcal.mol−1) is stronger than the mono-Mg ion system (BE = −39.57 kcal.mol−1). The attachment of first Mg2+ to the BQMCP facilitate the attachment of another Mg ion. The BQMCP shows higher positive redox potential, which decreases with the increase of Mg atoms with the high storage capacity of twelve Mg ions/ BQMCP unit at redox-active sites without any structure distortion. Mg ions successfully entraps in bulk porous stacked BQMCP layers with higher negative binding energy values. The results demonstrates that the BQMCP is a promising cathode material for magnesium ion batteries in future. [ABSTRACT FROM AUTHOR]

We communicate theoretical results of the structural, electronic, and optical properties of ZnOxTe1-x (0≤x≤1) in the zincblende structure. The calculations are performed using full potential linearized augmented plane waves (FP-LAPW) method, based on density functional theory (DFT). The structural properties are calculated with simple GGA (PBEsol), while the electronic and optical properties are calculated using mBJ-GGA. The mBJ-GGA is used to properly treat the active d-orbital in their valence shell. The ZnOTe alloy is highly lattice mismatched and consequently the lattice constants and bulk moduli largely deviate from the linear behavior. The calculated bandgaps are in agreement with the experimentally measured values, where the nature of bandgaps is direct for the whole range of x except at x=0.25. We also calculate the bandgap bowing parameter from our accurate bandgaps and resolve the existing controversy in this parameter. [ABSTRACT FROM AUTHOR]

Osmium based perovskites AOsO 3 (A=Ca, Sr and Ba) have been studied theoretically using density functional theory approach. These studies show that CaOsO 3 and SrOsO 3 are orthorhombic and BaOsO 3 is cubic and are consistent with the experiments. The electronic band structures demonstrate that these compounds are metals. The magnetic studies verify the experimental observations at low temperature, where the spin effects are canceled by the orbitals. The stable magnetic phase optimizations and magnetic susceptibilities calculations by the post-DFT treatment confirm that CaOsO 3 and SrOsO 3 are weak ferromagnetic whereas BaOsO 3 is a paramagnetic material. The directional magnetic study shows that these compounds are magnetically anisotropic, and reveals that the easy magnetization axis is [001] direction. [ABSTRACT FROM AUTHOR]

The electronic properties of complex binary skutterudites, MX 3 (M = Co, Rh, Ir; X = P, As, Sb) are explored, using various density functional theory (DFT) based theoretical approaches including Green's Function (GW) as well as regular and non-regular Tran Blaha modified Becke Jhonson (TB-mBJ) methods. The wide range of calculated bandgap values for each compound of this skutterudites family confirm that they are theoretically as challenging as their experimental studies. The computationally expensive GW method, which is generally assume to be efficient in the reproduction of the experimental bandgaps, is also not very successful in the calculation of bandgaps. In this article, the issue of the theoretical bandgaps of these compounds is resolved by reproducing the accurate experimental bandgaps, using the recently developed non-regular TB-mBJ approach, based on DFT. The effectiveness of this technique is due to the fact that a large volume of the binary skutterudite crystal is empty and hence quite large proportion of electrons lie outside of the atomic spheres, where unlike LDA and GGA which are poor in the treatment of these electrons, this technique properly treats these electrons and hence reproduces the clear electronic picture of these compounds. [ABSTRACT FROM AUTHOR]

In this work, spin-polarized density functional theory calculations are conducted to evaluate the possible applicability of a single Si atom doped boron nitride graphyne-like nansoheet (Si@BN-yne) for reduction of nitrous oxide (N 2 O). The calculations show that Si-doping in BN graphene is energetically favorable, and the resulting Si@BN-yne is both dynamically and thermodynamically stable. According to our findings, N 2 O spontaneously dissociates when it interacts with the Si@BN-yne from its O site without the need for an energy barrier, releasing 2.89 eV of energy. The adsorption energy of CO molecule on the Si@BN-yne is less negative than that of N 2 O, implying that N 2 O will predominately occupy the catalyst surface. The CO + O ad reaction is used to remove the remaining oxygen atom (O ad) from the Si@BN-yne surface. The calculations show that the reaction proceeds through a low energy barrier of 0.05 eV, which is much lower than the previously reported catalysts. This demonstrates the high catalytic activity of Si@BN-yne nanosheet. Furthermore, the adsorption of H 2 O and O 2 species on the Si@BN-yne nanosheet is investigated. The results show that the presence of these species has no effect on the catalytic activity of the Si@BN-yne for N 2 O reduction. These results show that the proposed novel Si@BN-yne catalyst can be regarded as an efficient material in the development of promising active catalysts for N 2 O elimination from the environment. [Display omitted] • Si-doping modifies the electronic structure of BN-yne. • N 2 O interacts weakly with the pristine BN-yne. • N 2 O dissociates spontaneously over Si@BN-yne. • The activation barrier for removing O ad from Si@BN-yne is 0.05 eV. [ABSTRACT FROM AUTHOR]

We present a review on the research developments on the theoretical electronic properties of the antiperovskite materials. The antiperovskite materials have perovskite type structure with the positions of cations and anions interchanged. The electronic structures are used to explain different physical properties of materials; therefore it is crucial to understand band structures and densities of states of materials for their effective use in technology. The theoretical results of the electronic structure of antiperovskites were discussed and compared with the available experimental results to measure the accuracy of the research done so far on these materials. The important physical properties of these compounds like magnetic properties and superconductivity are also highlighted. Nevertheless the thermoelectric properties of these materials are still unexplored except for a few reports which suggest that antiperovskite materials may be potential candidates for thermoelectric generators. [ABSTRACT FROM AUTHOR]

DFT calculations are used to investigate the CO oxidation over Al-decorated C 24 N 24 fullerene using the Langmuir Hinshelwood (LH) and Eley Rideal (ER) mechanisms. The Al atom is strongly attached to the surface of C 24 N 24. The ER mechanism is energetically more favorable for CO oxidation than the LH mechanism and the recovery of catalyst is a barrier-free process. [Display omitted] Recently, there has been a lot of interest in single atom catalysts for removing CO from the environment. Using density functional theory, the reaction pathways and activation barriers for CO oxidation over Al-decorated C 24 N 24 fullerene (Al@C 24 N 24) are investigated. The results demonstrate that Al incorporation in C 24 N 24 is energetically favorable and serves as the active site for catalytic activity. The CO and O 2 molecules bind strongly to the Al atom. For CO oxidation, two potential reaction routes are investigated: the Langmuir Hinshelwood (LH) and Eley Rideal (ER). Comparison of barrier energies reveals that the oxidation process proceeds through the ER mechanism. The CO + O* reaction occurs fast over the Al@C 24 N 24 surface, with no requirement for an energy barrier, reveals high catalytic activity of the studied catalyst. These findings suggest that the proposed catalyst might be useful in developing innovative noble metal-free catalysts for CO removal from the environment. [ABSTRACT FROM AUTHOR]

Mg-rich intermetallic NdNiMg 5 in orthorhombic phase with space group Cmcm (No. 63) has been studied theoretically using hybrid functional (HF–B3PW91) within the frame work of density functional theory (DFT). The calculated structural parameters and geometries are found in good agreement with the experiments. The electronic properties of the material reveal the metallic nature. Nd 4f-states splitting show that A 2 , y[t 1 ] and z[t 1 ] contributed in the valence band; x[t 1 ], ksi[t 2 ] and eta[t 2 ] in conduction band; where zeta[t 1 ] state completely lay at the Fermi level make the compound metallic. The electrical properties show that the material has significant conductivity above the room temperature. The stable magnetic phase of the compound is optimized which show that the material is stable in G-type antiferromagnetic (AFM) phase and Nd–Ni direct magnetic exchange interactions are involved. The calculated effective magnetic moments of Nd is 3.70 μ B per unit cell. The post-DFT calculations also confirm the AFM phase of the compound with Neel temperature (T N) = 25 K and Curie-Weiss constant (θ) = −23 K. Based on the above physical properties it is expected that this intermetallic could be used in spin valve and magnetic memory devices. • Mg-rich intermetallic NdNiMg 5 has been investigated theoretically using hybrid density functional theory. • The electronic properties of the material reveal the metallic nature. • The electrical properties show that the material has significant conductivity above the room temperature. • Stable magnetic phase of the compound is G-type anti-ferromagnetic phase. • The post-DFT calculations also confirm the AFM phase of the compound. [ABSTRACT FROM AUTHOR]

AMn 3 V 4 O 12 (A = Ca, Ce and Sm) quaternary perovskites are studied in the domain of density functional theory using various potentials. Generalized gradient approximation along with Hubbard U and hybrid density functional schemes are found effective tools for the treatment of these compounds. Changing of A-site cation, affects the physical properties due to the valence distributions Ca+2Mn+2 3 V+4 4 O 12, Ce+3Mn+2 3 V+3.75 4 O 12 and Sm+3Mn+2 3 V+3.75 4 O 12 respectively. Cohesive energy and enthalpy show that these compounds are thermodynamically stable. Electronic and electrical properties reveal the semi-metallic nature of these compounds. It is observed that in these compounds Aʹ-site (Mn) 3d electrons are localized and responsible for the magnetic properties whereas B-site (V) 3d electrons are delocalized, contributed in the electronic behavior. The elastic properties also confirm the stability and demonstrate that these compounds are ductile in nature. DFT as well as post−DFT treatments verify the anti-ferromagnetic nature of these compounds with the dominant Mn+2―O−2―Mn+2 super exchange interactions. • Cohesive energy and enthalpy show that these perovskites are thermodynamically stable. • Elastic properties confirm the stability and demonstrate that these compounds are ductile. • Electronic band profiles and electrical properties reveal the semi-metallic nature of the compounds. • These compounds are anti-ferromagnetic with the dominant Mn+2―O−2―Mn+2 super exchange interactions. [ABSTRACT FROM AUTHOR]