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The investigation of interface residual stress and interface elastic moduli tensors plays a crucial role in enhancing the conventional theory of elasticity. These considerations allow us to account for size effects and eliminate nonphysical singularities near defects. The primary objective of this study is to comprehensively calculate interface energy, residual stress components, and interface elastic moduli tensors for various interfaces between non-magnetic fcc metals using density functional theory (DFT). We achieve this by performing ab initio DFT calculations to determine the interface energies for different coherent interfaces among these metals. Subsequently, these energies are integrated into the corresponding formulations within surface/interface elasticity theory, enabling us to derive the residual stress and interface elastic constants specific to the target interface. Additionally, we identify and analyze unstable interfaces that exhibit phase transformations, cleavage, and mixing instabilities. Validation is also made with the available laboratory experimental results. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, the electronic, optical, and photovoltaic properties of the two double perovskites were determined, represented, and interpreted using ab initio calculations. The calculations were based on the generalized gradient of Perdew, Burke and Ernzerhof and Tran-Blaha-modified Becke-Johnson approximations within the framework of density functional theory. Quantities that predict the use of dual perovskites in photovoltaic, such as external quantum efficiency, open-circuit voltage and short-circuit current were calculated. These quantities were calculated based on optical properties, in particular the dielectric function, reflectivity, and absorption coefficient. Based on the electronic properties, the gap values obtained with TB-mBJ are 2.13 eV and 1.65 eV, while those obtained with GGA-PBE are 1.48 eV and 1.07 eV for Cs 2 AgBiBr 6 and Cs 2 AgSbBr 6 , respectively. The variations in external quantum efficiency and optical absorption coefficient show a strong evolution around the range of energies making up the visible spectrum. This makes them promising materials for the photovoltaic industry. We will apply various pressure values, ranging from 0 to 30GPa, to our structures in order to gain an improved comprehension of the effect of pressure on the energy loss function. [ABSTRACT FROM AUTHOR]

Assembling two dimensional (2D) materials in vertical heterostructures is one of the main techniques for tuning electronic and optical properties. In most cases, known as van der Waals heterostructures (vdWHs), the interlayer distances are larger than typical covalent bond lengths resulting in weak interlayer interactions. It has been shown that reducing the distance between the layers can significantly alter the properties of separated layers, which is not so noticeable in vdWHs and thus creates a new platform for controlling the physical properties of 2D materials. Motivated by enhanced properties of 2D vertical heterostructures, employing ab-initio calculations based on density functional theory we examined CdO/SnC systems in four different configurations. Our results reveal that in spite of thermodynamic and mechanical stabilities of all considered structures, according to the calculated phonon frequencies, only the structure formed by placing the Sn atom on the O atom and the C atom on the Cd atom is dynamically stable at zero temperature. This structure has an interlayer distance of 2.52 Å which is smaller than the interlayer distance in typical vdWHs. We investigated the electronic and optical properties of this dynamically stable structure utilizing GW approximation and solving Bethe–Salpeter equation. Unlike the monolayer CdO which possesses a single optical absorption peak close to the red light energy, the considered CdO/SnC structure has an optical band gap of 1.14 eV, and it can absorb 13% of incident light in the blue light region. [ABSTRACT FROM AUTHOR]

This study employs density functional theory (DFT) and density functional tight-binding theory (DFTB) to determine the adsorption properties of carbon dioxide (CO 2), methane (CH 4), and dihydrogen (H 2) in carbophenes functionalized with carboxyl (COOH), amine (NH 2), nitro (NO 2), and hydroxyl (OH) groups. We demonstrate that carbophenes are promising candidates as adsorbents for these gasses. Carbophenes have larger CO 2 and CH 4 adsorption energies than other next-generation solid-state capture materials. Yet, the low predicted desorption temperatures mean they can be beneficial as air scrubbers in confined spaces. Functionalized carbophenes have H 2 adsorption energies usually observed in metal-containing materials. Further, the predicted desorption temperatures of H 2 from carbophenes lie within the DOE Technical Targets for Onboard Hydrogen Storage for Light-Duty Vehicles (DOEHST) operating temperature range. The possibility of tailoring the degree of functionalization in combination with selecting sufficiently open carbophene structures that allow for multiple strong interactions without steric hindrance (crowding) effects, added to the multiplicity of possible functional groups alone or in combination, suggests that these very light materials can be ideal adsorbates for many gases. Tailoring the design to specific adsorption or separation needs would require extensive combinatorial investigations. • CO 2 and CH 4 adsorption energies larger than other solid-state capture materials. • CO 2 and CH 4 desorption temperatures mean they may be beneficial in confined spaces. • H 2 adsorption energies usually observed in metal-containing materials. • Desorption temperatures of H 2 lie within the government indicated ranges. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-diffusion coefficients for the fastest mechanisms are evaluated. • Ti diffuses along the c axis faster than in the perpendicular direction. • Self-diffusion is dominated by Ti on its own sublattice. • Doping with transition metals reduces the Ti diffusion rate. The mechanisms of the Ti and Si self-diffusion in the Ti 5 Si 3 compound are investigated by using the projector augmented-wave method within the density functional theory. The migration and activation energies for Ti and Si atoms were calculated for both vacancy and interstitial mechanisms. It is shown that the smallest migration energy of Ti atom corresponds to the interstitial mechanism, whereas it is by 0.08 eV lower for the Si own-sublattice mechanism than for interstitial one. The concentration of initial point defects within canonical formalism is calculated and the most preferred defects are determined. The temperature-dependent self-diffusion coefficients along two crystallographic directions are calculated. It is shown that Ti atom diffuses faster than Si one. The influence of metals of IVB–VIIB groups on the Ti migration energy is estimated. It is shown that almost all considered impurities increase the migration energy and can lead to a decrease in Ti diffusivity in Ti 5 Si 3. [ABSTRACT FROM AUTHOR]

Pt 2 Ga and Pd 2 Ga monolayers are high-efficiency multifunctional electrocatalytic materials. [Display omitted] • We theoretically report two novel 2D electrocatalysts with low Pt loading. • The HER activity of Pd 2 Ga monolayer is higher than that of currently commercialized Pt. • Pt 2 Ga monolayer possesses extremely lower overpotentials for OER and ORR, which can act as high-performance multifunctional electrocatalysts. • We provide an effective guidance for the rational design of multifunctional electrocatalysts. Developing multifunctional electrocatalysts with high performance for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is still a challenging task. In this work, the electrocatalytic activities of Pt 2 Ga and Pd 2 Ga monolayers are systematically investigated based on first-principles calculations. The high dynamic and thermal stabilities of Pt 2 Ga and Pd 2 Ga monolayers are confirmed by phonon dispersion calculations and ab initio molecular dynamics (AIMD) simulations, respectively. In addition, the Pd 2 Ga free energy for H adsorption is predicted to be −0.03 eV, implying its extremely high activity for HER. Furthermore, the Pt 2 Ga overpotential for OER and ORR are estimated to be 0.48 and 0.42 V, correspondingly, indicating its high catalytic performance. This work provides adequate guidance for designing multifunctional electrocatalysts with high performance for OER, ORR and HER. [ABSTRACT FROM AUTHOR]

[Display omitted] The reactions of the γ-U (0 0 1) and (1 1 0) surfaces in contact with O 2 were investigated by density functional theory (DFT), ab initio thermodynamic methods and ab initio molecular dynamics simulations (AIMD). The adsorption of the O atom and O 2 molecule on the (0 0 1) and (1 1 0) surfaces and subsurface are first studied, which provides insights into the adsorption, dissociation, and diffusion of O 2 on the surfaces. Furthermore, the effects of coverages on surface adsorption are considered to help us further understand surface oxidation corrosion. Based on the above research, we can speculate on the initial process of surface corrosion: 1. O 2 molecules in the atmosphere first approach the U surface in the form of physical adsorption; 2. O 2 molecules dissociate into O atoms on the surface; 3. O atoms diffuse on the surface after overcoming a small energy barrier and eventually occupy hollow (H) sites; 4. O atoms penetrate from the H sites to the subsurface; 5. The diffusion of O atoms inside the metal is more likely to be carried out by octahedral interstitial sites. Moreover, the adsorption phase diagrams indicate that O 2 will readily react with U even under ultra-high vacuum conditions, which is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The effects of pressure on the structural, electronic and mechanical properties of tetragonal NbAl 3 and cubic Nb 3 Al have been investigated using first-principles density functional theory approach within the generalized gradient approximation. The calculated structural parameters of two compounds were in good agreement with previous theoretical and experimental data, which linearly decreased with the increasing pressure. The electronic properties of two compounds under pressure have been analyzed. The enhanced covalence under pressure was found due to the increased hybridization between Nb-4d and Al-3p states. The independent elastic constants and mechanical properties have been calculated under pressure. We found that the pressure had a very important influence on mechanical properties. Finally, the ductile/brittle character and mechanical stability of two compounds have been discussed. [ABSTRACT FROM AUTHOR]

We examine the structural and electronic properties of BiNiO 3 and La-substituted BiNiO 3 of triclinic structure (space group P -1) with the use of DFT + U calculations. Both LSDA + U and GGA + U approaches predict the insulating ground state of BiNiO 3 system with G-type antiferromagnetic structure in the range 5 < U < 8 eV. The best agreement with experiment is found for GGA + U with U = 7 eV. Special attention is paid to changes in the calculated Ni O Ni bond angles in BiNiO 3 and La-substituted BiNiO 3 imposed by +U correction. The calculated electron localization function qualitatively reveals the charge disproportionation at Bi sites (Bi 3+ and Bi 5+ ) in the triclinic phase of BiNiO 3 . The total energy calculations of La-substituted BiNiO 3 in the triclinic phase with La replacing Bi 5+ ion show that the G-AFM ordering has the lowest energy for the system containing 25% of La. [ABSTRACT FROM AUTHOR]

Nanoalloys have been investigated for a wide range of applications, however, our atomistic understanding of the physical-chemistry properties is still far from complete as quantum-size effects play an important role for particles with about 1 nm diameter. In this work, we employed density functional theory calculations to investigate the structural, energetic and electronic properties of 55-atom A 55- n B n nanoalloys, where A , B = Al, Cu, Zn, and Ag. For structure generation, we combined clustering algorithm techniques with design principles, which yields a wide range of conformations. From the analyses of the excess energy results, we found that the CuAl, CuAg, CuZn, and AlAg systems are the most energetically favorable, in particular, the Al 42 Cu 13 and Al 42 Ag 13 compositions (onion-like and core–shell structures, respectively). Through Spearman's correlation analysis, we found that the structural properties (number of under coordinated atoms, effective coordination number, average bond lengths, and chemical order parameter) are the most important descriptors correlated with the energy stability of the nanoalloys (excess energy). Several properties such as the particle volume, binding energy, and average bond length show a linear dependence as a function of composition. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) based first-principles investigation has been performed to study the cohesive, elastic and electronic properties of Fe–Zr binary intermetallics across the composition range. Our initial calibration of underlying DFT approximations provides good agreement of lattice parameters and bulk moduli with experimental results. Ground state stability analysis indicates C15-Fe 2 Zr Laves phase to be the most stable and t-FeZr 2 to be more stable than c-FeZr 2 . All Fe–Zr intermetallics are mechanically stable as estimated from their calculated elastic constants. The calculated elastic moduli, in general, decrease with increasing Zr concentration. Anisotropies in bulk, shear and Young moduli are also presented. All the binary intermetallic phases exhibit G/B value of less than 0.57 and hence are ductile due to the presence of dominant metallic bonding arising from Fe d –Zr d interactions with a small component of covalent character. [ABSTRACT FROM AUTHOR]

In this work, the effects of small ternary additions to B2 NiTi structures was investigated through DFT calculations. The analysis considered deviations from stoichiometry arising from either simple substitution of host atoms in a given sublattice or from the formation of anti-sites. The calculations enabled the determination of the site preference of X ternary additions. Moreover, the results suggest that ternary additions located in the central region of the transition metal group across all periods tend to occupy Ni sites due to favorable X–Ti nearest neighbor (NN) interactions. This occupancy is achieved through substitution or through the generation of anti-site defects. On the other hand, ternary additions at both ends of a given transition metal row tend to occupy Ti sites due to favorable X–Ni NN interactions. Once site preferences are determined, the effect of alloying on the thermodynamic and mechanical properties of B2 NiTi–X structures are presented and trends are discussed. [ABSTRACT FROM AUTHOR]

Elastic and thermodynamic properties for the stable phases in the Nb–Al system were studied with the first-principles pseudo-potential plane-wave method based on density functional theory. The temperature dependence of the enthalpy of formation for the NbAl 3 and Nb 2 Al intermetallics are reported for the first time using the quasi-harmonic approximation. The elastic properties of Nb 2 Al and the linear thermal expansion coefficient and the elastic properties versus temperature of the Nb 3 Al are reported for the first time. The calculations would suggest that the NbAl 3 is the stiffest and most brittle of the Nb–Al intermetallics. [ABSTRACT FROM AUTHOR]

Understanding the iron adsorption on the surface of particles is important to predict their nucleation activity and find efficient precipitates. Ab initio calculations of adsorption energy for Fe on the (0 0 1) MX surface ( M = Ti, V, Nb, Zr, Hf or Ta and X = C or N) were performed to study the initialization of Fe nucleation. We find that the trends in Fe adsorption as dependent on the M and X atoms do not follow the lattice parameter or surface energy of MX , but are closely related to the number of the M and X valence electrons. The strongest binding was predicted for Fe on (0 0 1)NbC, and this carbide should have the high nucleation potential at early stage that is consistent with the observed grain refinement of ferritic and austenitic steels with NbC. In order to establish the alloying effect, we studied the adsorption of 3 d atoms ( M = Ti, V, Cr, Mn, Co, and Ni) on (0 0 1)NbC and concluded that Cr and Mn may compete with Fe in adsorption. The calculations of Fe adsorption on the NbC surface covered with 3 d atoms demonstrated that the initial layer of the Cr or Mn atoms enhances the subsequent Fe adsorption. [ABSTRACT FROM AUTHOR]

A robust, modular, and ab initio high-throughput workflow is presented to automatically match and characterize solid–solid interfaces using density functional theory calculations with automatic error corrections. The potential energy surface of the interface is computed in a highly efficient manner, exploiting the high-symmetry points of the two mated surfaces. A database is automatically populated with results to ensure that already available data are not unnecessarily recomputed. Computational parameters and slab thicknesses are converged automatically to minimize computational cost while ensuring accurate results. The surfaces are matched according to user-specified maximal cross-section area and mismatches. Example results are presented as a proof of concept and to show the capabilities of our approach that will serve as the basis for many more interface studies. [Display omitted] • A workflow to compute potential energy surfaces of hetero-interfaces is presented. • Computational parameters and slab thicknesses are converged automatically. • The slabs are matched and strained according to their relative stiffness. • The PESs are sampled by utilizing unique combinations of high-symmetry positions. • Results are collected in an easily shareable and query-able database. [ABSTRACT FROM AUTHOR]

The behavior of atomic hydrogen in osmium dioxide and ruthenium dioxide is investigated through ab initio calculations using density functional theory. Interstitial hydrogen behaves as a donor in both metal oxides and only has one stable interstitial position, bonding with an O atom to form an OH O defect. The rates of diffusion parallel to the c -axis are estimated to be 3.95 × 10 − 7 exp(−0.793/ k B T ) m 2 /s and 3.64 × 10 − 7 exp(−0.659/ k B T ) m 2 /s in OsO 2 and RuO 2 , respectively. The rates of diffusion perpendicular to the c -axis are estimated to be 1.80 × 10 − 6 exp(−0.941/ k B T ) m 2 /s and 1.10 × 10 − 6 exp(−1.21/ k B T ) m 2 /s in OsO 2 and RuO 2 , respectively. Additionally, the binding energy of multiple H atoms in (O, Os, Ru) vacancies have been calculated. High binding energies of hydrogen in metal vacancies result in multiple H atoms associating with a single metal vacancy. In RuO 2 , the binding energy of multiple H atoms outweighs the formation energy of a single Ru vacancy as well as that of a Ru–O divacancy. [ABSTRACT FROM AUTHOR]

In the present work, five different atomic configurations of fully hydrogenated silicene/graphene hybrid sheet, namely chair, boat, zigzag, armchair and table have been studied. Using DFT-based calculations method, it was found that the arrangement of the absorbed hydrogen atoms influences significantly the structural and electronic properties of the hybrids. It was also demonstrated that the five structures are stable and that full hydrogenation of SiC in different configurations are exothermic adsorptions, except in table conformer. Charge density calculations revealed that a large amount of electric charge is condensed around C atoms, whose orbitals contribute mainly, with regard to H and Si atoms, in the energy gap of silicane–graphane conformers. The overall results of this work show that silicane–graphane hybrids is a promising potential candidate not only for nano-electronic applications but also for hydrogen storage. [ABSTRACT FROM AUTHOR]

[Display omitted] Ab initio calculations were used to determine physical properties of AlN(0001) surface under Al coverage. It was shown that Al atoms are adsorbed in T4 sites for very low Al coverage, up to θ Al = 1 / 4 monolayers (ML). For higher Al coverage, θ Al = 1 / 4 M L up to θ Al = 1 M L the adlayer becomes disordered and corrugated vertically. In this coverage range ( 0 < θ Al ≤ 1 M L) the Al bonding energy is independent on the coverage and equal to E ads DFT ≅ 5.0 e V. For higher coverage, 1 M L ≤ θ Al ≤ 7 / 6 M L , the Al adlayer becomes ordered and atomically flat. The Al adsorption energy in this range is E ads DFT ≈ 6.0 e V , i.e. much higher. For higher coverage, θ Al > 1.25 M L , the Al adatoms are located in the second layer. The adsorption energy is reduced to E ads DFT = 3.97 e V at θ Al = 1.25 M L and linearly increasing to E ads DFT = 4.88 e V for the coverage increase up to θ Al = 2 M L. Full thermodynamic analysis identified two regions in equilibrium with Al vapor: first at very low pressures where θ Al ≤ 10 - 3 M L and the second for higher pressures which is 1 M L ≤ θ Al ≤ 7 / 6 M L. The second region is relevant for physical vapor transport (PVT) AlN growth. The nitrogen adsorption process, important for PVT AlN growth, takes place at single or double Al layer covered AlN(0001) surface. [ABSTRACT FROM AUTHOR]

[Display omitted] Mayenite (12CaO · 7Al 2 O 3 or generally named C12A7) and its electride form (C12A7 : 4 e −) have drawn intensive attention because of a variety of promising applications including display devices, catalysis, and transistors. C12A7 is a transparent insulator and it can be controllably engineered to a conductor or superconductor upon introducing oxygen vacancies and substitutional anionic impurities. However, the influence of external pressure on electronic and optical properties of C12A7 remains intriguingly less explored. On the basis of the density functional theory (DFT) and ab initio molecular dynamics, this work presents the variations of electronic and optical properties of C12A7 via the immense external pressure. The findings reveal that the applied pressure induces the structural deformation until it is energetically amorphised at pressure greater than 17.94 GPa. Such deformation consequently creates the gradual reduction in the electronic band gap because of the intensified overlap of electronic bands among the framework Ca-3 d , O-2 p , and the in-cage extra-framework O-2 p states. Furthermore, the drop in the band gap yields the remarkable enhancement in the optical absorbance in the visible and UV regions. Our findings unveil the underlying influences of the external pressure on the C12A7 properties which are of fundamental interests and functional design for applications. [ABSTRACT FROM AUTHOR]

First principles based calculations reveal that Xe/Kr separation abilities of SBMOF-2 are determined by structural and electronic nature of the pore channels. • SBMOF-2 yields good uptake capacity and selectivity for Xe/Kr separation. • Effect of structural and chemical characteristics of pore channels on noble gas adsorption. • A new efficient SBMOF-2 with Mg as central metal atom is suggested. • The adsorption trend from our simulations match with experimental observations. • The ligand functionalization improves the Xe/Kr adsorption properties significantly. Radioactive Xe and Kr released from nuclear reactors and spent nuclear fuel reprocessing plants can be converted in to useful ones after the radioactive decay. The adsorption techniques employing porous materials are a cost effective solution for the capture of these volatile radionuclides compared to expensive cryogenic distillation process. Among various porous materials, metal-organic frameworks (MOFs) show excellent storage and separation properties. In this paper, we investigate the Xe and Kr adsorption properties of recently reported SBMOF-2 using van der Waals corrected density functional theory. In particular, SBMOF-2 has two types of pores with distinct linker groups along pore channels. Our studies show that Xe is preferred over Kr in both the pore channels, which are in complete agreement with experimental observations. The adsorption energies obtained for SBMOF-2 is comparable to other efficient MOFs reported in the literature for Xe/Kr separation. The two pore channels show slightly different binding energies depending on their linker groups and pore characteristics. The impact of central metal atom on adsorption properties is evaluated. A new SBMOF-2(Mg) with magnesium as central metal atom shows Xe/Kr adsorption behavior similar to the experimentally studied SBMOF-2(Ca). Next, we have investigated the effect of polarizable groups in the pore channels where linker hydrogen atoms are substituted with halogen atoms. There is a significant increase in the adsorption energy of noble gases in the halogenated pore channels. Due to the presence of halogen atoms, electron charge density redistribution takes place in the MOF network leading to permanent dipoles. Accordingly, the adsorption energies increase with the polarizability of halogen atoms. The ab initio calculations performed in this study suggest that Xe/Kr separation properties of MOFs depend upon many competing interactions, which originate from their structural and chemical properties. [ABSTRACT FROM AUTHOR]