Search

Metal fluorides are ionic compounds with intriguing properties and a wide range of industrial and technological applications. In this paper, we present the results of an extensive first-principles study of the electronic band structure of nineteen mono-, di-, and tri-fluorides. Four approaches are employed in this study: LDA, pseudopotential and all-electron modified Becke–Johnson (mBJLDA@PP and mBJLDA@AE) potentials, and Yukawa Screened Hybrid Functional (YS-PBE0). The mBJLDA and YS-PBE0 band gaps are in good overall agreement with the available G 0 W 0 results and experimental data, which ensures the reliability of the provided predictions for systems where accurate band gaps are lacking. The LDA and YS-PBE0 upper valence band (UVB) widths are very close to each other, and these results are, in general, slightly smaller than the G 0 W 0 results and experimental data. It is shown that the band gap and UVB width vary with F F distance, and distinct trends are identified. The LDA density of states of the UVB for the alkali and alkaline-earth fluorides are analyzed and compared to the available XPS and XES spectra. It is found that the LDA approach provides accurate results for peak intensities as well as satellite peak positions relative to the main peak. A strong correlation is demonstrated between the adopted crystal structures of the considered fluorides and their bond ionicity. • Four approaches are used to study the electronic structure of 19 metal-fluorides. • For several of the fluorides considered, reliable predictions have been made. • Band gaps and upper valence band widths are found to exhibit clear trends. • The bonding mechanisms of fluorides are discussed in detail. • A correlation is established between bond ionicity and crystal structure. [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]

We calculated electronic structure of Ce 2 Rh 3 Ga 9 , Ce 2 Ru 3 Ga 9 , La 2 Ir 3 Al 9 and Ce 2 Ir 3 Al 9 compounds and we found that Ce 2 Ir 3 Al 9 may exhibit strong topological insulator state according to Z 2 index estimation based on parity algorithm and shape of band structure near Fermi level. The same algorithm shows strong topological insulator state for La 2 Ir 3 Al 9 and Ce 2 Rh 3 Ga 9 compounds, but their band structure near Fermi level is more like semimetallic one. Ce 2 Ru 3 Ga 9 is a normal metal. Our calculations show no magnetic ordering for studied compounds. We also measured the XPS (X-ray Photoelectron Spectroscopy) spectra for these materials, and compared the valence band with simulated spectra, where good agreement was found. Core level states were also investigated and compared with Mulliken population analysis results. According to our measurements and calculations, the highest Ce valence is observed for Ce 2 Ir 3 Al 9 whereas for Ce 2 Rh 3 Ga 9 and Ce 2 Ru 3 Ga 9 the Ce valence is smaller. Hybridization between conduction electrons and 4 f states is very small, and for Ce 2 Ru 3 Ga 9 essentially negligible. [Display omitted] • The first electronic structure calculations with FPLO method of Ce 2 Rh 3 Ga 9 , Ce 2 Ru 3 Ga 9 , La 2 Ir 3 Al 9 and Ce 2 Ir 3 Al 9 have been reported. • The calculations show, that in the case of Ce 2 Ir 3 Al 9 the hour glass-like structure is visible at Γ point, but this structure is visible slightly above the ϵ F. • We found that Ce 2 Ir 3 Al 9 may exhibit strong topological insulator state. • Our calculations show no magnetic ordering for studied compounds. • Moreover, we also found that hybridization of 4 f and conduction electrons is small for Ce 2 Ir 3 Al 9 and Ce 2 Rh 3 Ga 9 and close to zero for Ce 2 Ru 3 Ga 9. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methodology of spin-polarised ab-initio calculations is revisited. • Ferromagnetic HoN requires an unusually high number of unoccupied electronic states. • Electronic structure and crystal characteristics depend on magnetisation. • Capturing the experimental magnetic moment requires a large simulation cell. • Preferred spin distribution in rare-earth nitride HoN is predicted. Rare-earth mononitrides such as HoN exhibit a wide range of useful properties leading to potential applications as magnetic semiconductors, spintronic half-metals, or magnetocaloric refrigerants in hydrogen liquefaction systems. First-principle calculations of electronic structures and related properties of such materials should correctly reproduce their magnetic moment. First, we identify the unusually high number of unoccupied electronic states which guarantees that the energy minimum identified is the global one. Second, we develop a method which allows the experimentally relevant magnetisation to constitute an energy minimum, emphasising the favourable distribution of the spins in an exceptionally large simulation cell. Third, we examine the dependence of selected HoN characteristics on the cell size and on the magnetisation. The results provide a theoretical insight into the spin structure of rare-earth nitrides and allow one to use the correct methodology of similar calculations of properties of strongly correlated materials. [ABSTRACT FROM AUTHOR]

Graphical abstract The maximum absorption exists in the visible light region for all the phases studied; making In-doped AlFeO 3 suitable for energy harvesting applications. Highlights • Electron effective mass is smaller than that of holes for Al 1−x In x FeO 3. • Effective electron mass tensor is fairly isotropic; hole mass is not so. • High dielectric-constants of Al 1−x In x FeO 3 indicate promise for charge separation. • Reflectivity peaks for all the phases is found near IR and UV region. • Absorption-spectra indicate relevance for visible light harvesting. Abstract Electronic and optical properties of AlFeO 3 and Al 1−x In x FeO 3 (x = 0.25, 0.5, 0.75) are studied using ab-initio calculations. Electronic structure in the vicinity of the conduction band minimum (CBM) and valence band maximum (VBM), the effective masses of holes and electrons at the gamma point are calculated. The calculated effective masses of electrons is smaller than that of holes (m c1 ⊥, m c1 ‖ (m e *) < m v1 ⊥, m v1 ‖, m v2 ⊥, m v2 ‖ (m h *)), for all values of x; this is expected to contribute to the desirable photocatalytic performance. Effective mass tensor for electrons is found to be isotropic (unlike holes). The optical constants such as static dielectric constant, refractive index, extinction coefficient and absorption coefficient are comparable with that Si. The maximum absorption exists in the visible light region for all the phases studied; making In-doped AlFeO 3 suitable for energy harvesting applications. We noted from our previous work (Sudha Priyanga and Thomas, 2018) that the computed band gap values could be underestimated by as large as ∼0.5 eV. Even so, the reported phases would be relevant for light harvesting. [ABSTRACT FROM AUTHOR]

A design map in regard to the generalized-stacking fault (GSF) energy is plotted for Ti 5 Si 3 (Ti 60 Si 36 ) alloying with 12 ternary elements in { 1 1 ¯ 00 } [ 0001 ] slip system. Hereinto, alloying elements occupy preferable Ti sites near slip planes. The elements with a larger radius difference from Ti tend to reduce the GSF energies more dramatically. Moreover, the elements smaller than Ti are more prone to decreasing GSF energies than those larger than Ti. Accordingly, the addition of ternary elements, like Ni, Cu and Co, will lead to an obvious decrease in GSF energies by 18.0%, 16.7% and 13.4% respectively, and therefore may facilitate the initiation of prismatic stacking faults and furthermore enhance ductility. Note that the decline of GSF energies is attributed to the weakening covalent bonds between slip planes with the introduction of ternary elements. Our calculations provide a guide to experiments on the design of Ti 5 Si 3 compounds with tailored properties. [ABSTRACT FROM AUTHOR]

[Display omitted] Monolayer Indium Selenide (ML-InSe) is studied for 4x4 supercell structure through ab initio calculations. The electronic and optical properties of ML-InSe for both pristine and substitutional doped ML-InSe with Palladium (Pd), Platinum (Pt), Silver (Ag), and Gold (Au) atoms have been calculated. With substitutional doping, ML-InSe has been observed to have a spin-dependent electronic structure. The flat energy bands near the Fermi level are observed in ML-InSe with doping elements placed in In site. The flat bands of d orbitals of some noble metal atoms are formed by the projected density of states (PDOS). The PDOS calculations show that the s-orbital of In and p-orbital of Se form the conduction band edge. The energetically favorable position of doping atoms is found to be the Pt In substitution atom according to formation energy calculations. For each studied structure, the bond length of the first neighbor of doping atoms in doped ML-InSe, static dielectric constant (ε 0), refractive index, and energy band gap have been calculated. In the structure ML-InSe with Au Se , ε 0 reaches ∼ 8.15. Another important result is that substitutional doping induces some peaks in the lower energy region of the imaginary part of the dielectric function. These peaks mainly refer to the absorption in related regions and may be important for the optoelectronic properties of ML-InSe. [ABSTRACT FROM AUTHOR]

Spin–orbit coupling (SOC) drives interesting and non-trivial phenomena in solid-state physics, ranging from topological to magnetic to transport properties. A thorough study of such phenomena often requires effective models where the SOC term is explicitly included. However, the estimation of SOC strength for such models mostly depends on the spectroscopy experiments which can only provide a rough estimate. In this work, we provide a simple yet effective computational approach to estimate the onsite SOC strength using a combination of the ab initio and tight-binding calculations. We demonstrate the wider applicability and high sensitivity of our method by estimating SOC strength of materials with varying SOC strengths and the number of SOC active ions. As examples, we consider strongly correlated, topological, and semiconducting materials. We show that the estimated strengths agree well with the proposed values in the literature lending support to our methodology. This simplistic approach can readily be applied to a wide range of materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Understanding high-temperature superconductivity is nowadays a challenge in the area of quantum materials and presents major unsolved problems. The recent discovery of superconductivity in infinite-layer nickelates has provided a new platform for studying unconventional superconductivity. Although the nickelates are analogous to the cuprates high-temperature superconductors, many theoretical analyses indicate that the nickelates do not precisely mirror the cuprates. For instance, hybridization between Ni 3 d x 2 − y 2 and O 2 p is weak, which presents a high contrast to the hybridization between Cu 3 d and O 2 p in the cuprates. The similarities and differences between the nickelates and the cuprates provide great opportunities to reveal the origin of high-temperature superconductivity. In this study, with the employment of first-principles density-functional-theory calculations, we determine and analyze the electronic structure of the undoped infinite-layer nickelate NdNiO 2. By performing phonon calculations and estimating the strength of the electron–phonon coupling, we find that this latter is weak, which indicates that the conventional BCS theory alone cannot explain the observed superconductivity in this material. Consequently, other still-unknown mechanisms may be at play. Moreover, we show from electronic band calculations that another conduction band crosses the Fermi level in addition to the Ni 3 d x 2 − y 2 band. This non-Ni conduction electron band is mainly composed of three orbitals: Nd 5 d 3 z 2 − r 2 , Nd 5 d x y , and another s -like orbital that does not belong to any specific atom. This interstitial s -like orbital is located around the (0,0,0.5) site. The rare-earth orbital Nd 5 d 3 z 2 − r 2 mixes with Ni 3 d x 2 − y 2 at the Fermi level, which causes some holes from the Nd 5 d band to be (self-) doped into the Ni 3 d x 2 − y 2 orbitals. [Display omitted] • DFT electronic structure of NdNiO 2 is calculated. • Electron–phonon coupling in NdNiO 2 is weak. • Ni 3 d x 2 − y 2 , Nd 3 d 3 z 2 − r 2 / 3 d x y contribute to the Fermi surface. • A new s -like orbital centered at (0,0,0.5) also contributes to the Fermi surface. [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]

[Display omitted] • Calculations of phonon spectrum, mechanical properties, and thermodynamic properties. • α-(Al 0.75 Cr 0.22 Si 0.03) 2 O 3 compound is thermodynamically unstable. • α-(Al 0.75 Cr 0.22 Me 0.03) 2 O 3 exhibits semiconductor characteristics. • Changes in properties are influenced by the differences in electronic structures. α-(Al x Cr 1-x) 2 O 3 thin films have a wide application prospect due to their thermodynamic stable corundum structure and excellent mechanical and thermodynamic properties. In this study, theoretical investigations on the crystal structure, electronic structure, mechanical and thermodynamic properties of quaternary corundum structured α-(Al 0.75 Cr 0.22 Me 0.03) 2 O 3 (Me: Si, Fe, Mn, Ti, V, and Y) compounds have been explored by using ab-initio calculations. Results show that all compounds remain in the corundum structure, with stable mechanical and thermodynamic properties except for α-(Al 0.75 Cr 0.22 Si 0.03) 2 O 3 compound, which exhibits thermodynamic instability. Among all compounds, α-(Al 0.75 Cr 0.22 Fe 0.03) 2 O 3 exhibit the best mechanical properties with the highest modulus and hardness value, H V[TIAN] of 16.65 GPa. Changes in mechanical properties of the compounds result from the varied bonding and antibonding states around the E F. All compounds exhibited excellent semiconductor characteristics with indirect band gaps ranging from 0.03 to 1.51 eV. [ABSTRACT FROM AUTHOR]

• The stability of the M-segregated surface is higher than that of the non-segregated and Cu-segregated surfaces under vacuum condition; • The stability of the non-segregated surface is the highest at the CO coverage of 1/4 ML; • The surface-adsorbate binding strength directly affects the surface segregation tendency in a reactive environment. Segregation on the surface of metal alloys has a great influence on their electrochemical and catalytic properties. We have used ab initio calculations based on density-functional theory to study the surface segregation phenomena of Cu 3 M(1 1 1) (M = Au, Ag, and Zn) alloy systems with chemisorbed CO. The calculated results show that the chemical adsorption of CO can substantially change the segregation tendency of Cu 3 M(1 1 1) surface. The stability of the M-segregated surface is higher than that of the non-segregated and Cu-segregated surfaces under vacuum condition, while the stability of the non-segregated surface is the highest at the CO coverage of 1/4 ML. Moreover, the analysis of the CO adsorption behavior and the surface electronic structure indicates that the surface-adsorbate binding strength directly affects the surface segregation tendency in a reactive environment. This study provides a theoretical basis for the practical application of copper-based alloys as CO 2 reduction catalysts. [ABSTRACT FROM AUTHOR]

The ab-initio electronic structure calculations are used to investigate the half-metallic property, structural stability, spin dependent density of states and magnetism of transition metal (V, Cr, Mn, Fe, Co) substituted Zn 3 P 2 . Our results show the half-metallic ground state and ferromagnetic (antiferromagnetic) stability for small concentrations (2.5% and 5%) of transition metal atom substitution considered in our study. The structural and magnetic stability of the substituted compounds have been investigated through the calculation of the heat of formation and analyzing the minimum total energies corresponding to the ferromagnetic, antiferromagnetic and nonmagnetic phases. The substituted transition metal atom is found to give rise to magnetism of these compounds and half-metallic property is observed in many cases. We have used the spin, orbital and atom projected density of states to investigate this point and studied the nature of bonding in these systems using the charge density contours. We have observed from our calculations, magnetically stable phases and large values of the magnetic moments in these compounds and it suggests that these compounds may be useful materials for semiconductor spintronic devices. We have further calculated the theoretical X-ray diffraction pattern of these compounds. [ABSTRACT FROM AUTHOR]

The effects of zinc segregation on intergranular corrosion of the outermost surface layer of the AlΣ5 (0 1 2)/[1 0 0] grain boundary (GB) in an aluminium alloy have been investigated based on first-principles density functional calculations. It is demonstrated that the outermost surface of an Al GB with Zn atom segregation is less stable than that of the pure Al GB, and the first or second nearest-neighbour Al atom of a segregated Zn atom is more prone to corrosion dissolution than those in other sites. The electronic structure analysis shows that a charge reduction region forms along the grain boundary, which causes a more negative electrode potential shift than the pure Al GB. The Zn–Al bond has a metallic character that is similar to the Al–Al bond regardless of the degree of Zn segregation. It is confirmed that the corrosion of the outermost surface of the Al grain boundary with Zn segregation is enhanced because of the charge depletion among Al atoms and Zn atoms. This work contributes to our understanding of the comprehensive effects of Zn segregation on stress corrosion cracking of aluminium alloys. [ABSTRACT FROM AUTHOR]

First principles calculations are performed to investigate the structural stability, electronic and mechanical properties of ZnN and CdN for various structures: NaCl, CsCl, zinc blende, and NiAs. The local density and generalized gradient approximations are used for exchange and correlation effects. Our calculations indicate that zinc blende (ZB) phase is the lowest energy phase for ZnN while it is the NaCl phase for CdN at normal pressure. A pressure induced structural phase transition from zinc blende to NiAs phase is predicted in ZnN, whereas NaCl to zinc blende phase and then zinc blende to NiAs phase is observed in CdN. The ground state properties like lattice parameters, bulk modulus and cohesive energy are calculated. Electronic structure reveals that both ZnN and CdN are metallic. The computed elastic constants show that these nitrides are mechanically stable in their most stable phase. The shear modulus, Young’s modulus, Poisson’s ratio and Debye temperature are also calculated. The low bulk modulus value indicates that ZnN and CdN are more compressible compared to other transition metal nitrides. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electronic structure and thermodynamic properties of In1−x B x P alloys have been studied [•] The lattice parameters of the In1−x B x P alloys decrease with B-concentration. [•] The bulk modulus of the In1−x B x P alloys increases with composition x. [•] Band gap shows a transition from ΓΓ to ΓΔ at x =0.611(0.566) for LDA(PBE) functional. [•] Results indicate that In1−x B x P alloys are only stable at unusual high temperatures. [Copyright &y& Elsevier]

Abstract: Theoretical calculations of Ga1- x Mn x P and Ga1- x Mn x As (x =0.125) in the zinc blende phase are presented. The electronic structure and magnetic properties of these compounds are calculated and their correlation is investigated with the lattice compressions. The results show that, both the compounds hold their half-metallic nature, conductor for spin up state and semiconductor for spin down state, with their lattice compressions up to certain critical lattice constants. An abrupt change in the electronic and magnetic properties is observed at these robust transition lattice constants (RTLCs). These compounds loss their integer magnetic moments (4μβ) and tremendous decrease in the bandgaps (spin down states) start at these critical lattice constants and hence the materials transform from half-metals to degenerate semiconductors. The calculated RTLC for Ga0.875Mn0.125P is 5.14 Å and for Ga0.875Mn0.125As is 5.25 Å. The possible compression in the lattice constants from their relaxed states, while maintaining their half-metallic nature, is up to 6% for Ga0.875Mn0.125P and 8% for Ga0.875Mn0.125As. The feasibility of the growth of these compounds on different substrates on the basis of the variation in the lattice constants is also discussed. [Copyright &y& Elsevier]

Abstract: The electronic, elastic and mechanical properties of eight binary B 2 – type intermetallic compounds of Ag and Au (AgX and AuX, X=Mg, Sc, Zn and Cd) have been studied systematically using first principles density functional theory within generalized gradient approximation. Ground state properties such as lattice constant (a 0), bulk modulus (B), its pressure derivative (B′) and elastic constants are calculated. The present results are in good agreement with the experimental and other available theoretical results. Poisson’s ratio (σ), Young’s moduli (E), shear moduli (GH ) and the ratio of elastic anisotropy factor (A) are also estimated. Ductility for these compounds is further analysed by calculating the ratio of B/GH and Cauchy pressure (C 12–C 44). Amongst all the intermetallics AuZn is found to be most ductile due to the presence of strong metallic bonding, and AgZn is least ductile in all the Au and Ag intermetallic compounds. [Copyright &y& Elsevier]

Abstract: We have implemented the calculation of optical matrix elements with and without the inclusion of a real-space cutoff in the open-source software package ABINIT. We have also included the possibility to add the contribution arising from the non-local term of the pseudopotential operator. The implementation has been tested successfully for atoms, bulk silicon, and an oxidized silicon surface. [ABSTRACT FROM AUTHOR]

Abstract: To investigate the structural, elastic, and lattice dynamical properties of the germanium diiodide, we have performed the first-principles calculations by using the local density approximation method based on density-functional theory. Some basic physical parameters such as lattice constant, bulk modulus and its first derivatives, elastic constants, shear modulus, Young’s modulus, and Poisson’s ratio are calculated. The phonon dispersion curves, electronic band-structures, and total and partial density of states have also been calculated for ground state C6 phase of GeI2. Our results show that this structure has got 1.72eV direct band gap. Our secondary results on the temperature-dependent behavior of thermodynamical properties such as entropy, heat capacity, internal energy, and free energy are also presented for the same compounds. The obtained results are in good agreement with the available experimental and other theoretical data. [ABSTRACT FROM AUTHOR]

Abstract: Using first principles calculations, we have investigated the pressure effect on the structural properties of unexplored M2AC compounds, relevant to the so called MAX phases, with M=V or Nb and A=P or As. Band structure and bonding properties of these compounds were studied at 0 GPa. Our results for the lattice parameters a, c and the equilibrium volume v are in good agreement with the available experimental data. Relative change of the volumes, lattice parameters, M–C and M–A bonds length are studied up to 40 GPa. The bulk modulus was deduced from the Birch–Murnaghan equation of state. A systematic study on the effect of both M and A elements on the bulk modulus B, shows that the bulk modulus is more affected by the substitution of A atoms (P→As) than by the substitution of M atoms (V→Nb). We have also found that the band structure shows a metallic character of the investigated compounds. From the total and partial density of states, we could notice that the conductivity is mostly assured by the d electrons of the transition metal (M=V, Nb). The charge densities are presented and the chemical bonding are discussed and compared to the available data in the literature. [Copyright &y& Elsevier]

[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]

• Negative formation energies of alloyed Ti-Al/Al 2 O 3 systems were observed. • The alloying elements will enhance the adhesion of α 2 -Ti 3 Al/Al 2 O 3 interfaces. • There are connections between the stability, adhesion and the electronic structures. The influence of V, Cr, Nb, Mo, Ta, and W alloying elements on the stability and adhesion properties of γ-TiAl(111)/Al 2 O 3 (0001) and the α 2 -Ti 3 Al(0001)/Al 2 O 3 (0001) interfaces are studied via first principles calculations. All the considered alloying elements prefer to substitute for the Ti site in both the γ-TiAl(111) and the α 2 -Ti 3 Al(0001) surfaces, with occupation energy differences of more than 0.2 eV and 1.0 eV lower than Al site, respectively. The interfaces studied here own negative formation energy except the Cr alloyed γ-TiAl/Al 2 O 3 system. The alloying elements will enhance the bonding interactions of the α 2 -Ti 3 Al/Al 2 O 3 interfaces and maintain the strength of the γ-TiAl/Al 2 O 3 interfaces, most of the alloyed interfaces own work of adhesion of lower than −2.5 J/m2. Different charge transfer behaviors between Al 2 O 3 scale and Ti-Al intermetallics is probably the major factor that enhancing the adhesion of the considered systems. [ABSTRACT FROM AUTHOR]

• Ab initio calculation of formation enthalpy of Nd-Fe-B compounds with GGA + U method. • Phonon calculation of compounds to obtain heat capacity for 300 < T < 3000 K. • Re-optimization of binary Nd-B phase diagram using ab initio calculation results. • Improvement especially from results for NdB 6 compound. In this work, we report the results of ab initio calculations of thermochemical properties of several compounds in the Fe-Nd, B-Nd and B-Fe-Nd systems. We have performed DFT + U calculations to compute the enthalpy of formation of the compounds NdB 6 , NdB 4 , Nd 2 B 5 , Nd 2 Fe 17 and Nd 5 Fe 2 B 6 . It was found that the values obtained with an effective Hubbard U correction have better agreement with the experimental data. We have also computed the vibrational contribution to the heat capacity ( C p ) of the compounds as a function of temperature was computed using the quasiharmonic approximation. For most of the compounds these properties have not been experimentally determined until now. Electronic contribution to the heat capacity has been calculated as well from electronic structure calculations. A part of the results in this work has been applied to the re-optimization of the binary Nd-B phase diagram. [ABSTRACT FROM AUTHOR]