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Halide perovskites are an intriguing renewable energy materials that may assist in addressing the world's energy scarcity. The Goldsmith tolerance factor (0.99 and 1.00) and negative formation energy guarantee the examined materials' structural and thermodynamic stabilities. The Poisson's and Pugh's ratio proves the reviewed materials' ductile nature. K/RbOsCl 3 has electronic band gaps of 1.37 eV/1.39 eV and the highest light absorption in the ultraviolet and visible areas, enhancing its efficacy for solar cells and other optoelectronics technologies. The highest Seebeck coefficient and electrical conductivity render these materials feasible for thermoelectric properties. KOsCl 3 and RbOsCl 3 exemplify figures of merit of 0.89 and 0.88, respectively, at the ambient temperature. Additionally, the Debye model was implemented to figure out thermodynamic parameters such as heat capacity, thermal expansion, Debye temperature, and Grüneisen parameter., (© 2024. The Author(s).)

The Electronic and optical properties of InGeX 3 (X = Cl, Br) were examined by adopting the density functional theory (DFT) approach. We applied the GGA + Trans-Blaha modified Becke-Johnson (TB-mBJ) technique to acquire the precise bandgap of 1.52 and 0.98 eV of the compounds InGeX 3 (X = Cl, Br) respectively which suggests the direct bandgap at (M-M). The stability of the material is confirmed by the formation energy (- 2.83 = Cl; - 2.35 = Br) and Mechanical stability. Primarily elastic constants were extracted for each of the materials under scrutiny, and these values then served to gauge all of the materials' mechanical properties. The assessed Poisson's and Pugh's ratios for the materials InGeCl 3 and InGeBr 3 were verified to identify the degree of ductility. The quasi-harmonic Debye model additionally covers the temperature and pressure dependence on thermodynamic parameters, particularly volume, specific heat capacity (Cv) at constant volume, and the Gruneisen parameter (γ) in the range of 0-800 K and 0-5 GPa. It is anticipated that InGeCl 3 and InGeBr 3 will have static dielectric constants of 4.01 and 5.74, respectively. InGeX3(X = Cl, Br) also reveals significant absorption in the high UV spectrum. The thermoelectric properties have also been calculated vdata-element-id="9QNfR3VHbcMHX_W0fJCYp" data-element-type="html" style="display: initial; visibility: initial; opacity: initial; clip-path: initial; position: relative; float: left; top: 0px; left: 0px; z-index: 1 !important; pointer-events: none;" />ia boltztrap2 code using a k mesh of around 1,50,000 points., (© 2024. The Author(s).)

Here, we have investigated properties of caesium based halide perovskites with the help of density functional theory. We employed the generalized gradient approximation (GGA) functional to determine the structural characteristics. Conversely, for evaluating the electronic and thermoelectric properties of these materials we utilized the modified Becke and Johnson (mBJ) potential functional. Our findings indicate that these materials exhibit semiconducting properties. Furthermore, our analysis of the transport properties using the Boltzmann transport equation indicates that the studied perovskites are well-suited for thermoelectric applications., Competing Interests: The authors have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The present work employs density functional theory to explore the structural, optoelectronic, and thermoelectric attributes of the halide-based double perovskite A 2 GeSnF 6 (A = K, Rb, and Cs) compounds. The stable phonon dispersion spectrum affirms dynamical stability, whereas the enthalpy of formation and tolerance factor evaluated collectively verify structural stability. Considering the Tran Blaha modified Becke Johnson potentials (mBJ), the predicted direct band gaps along the symmetry point are 3.19 eV for K 2 GeSnF 6 , 3.16 eV for Rb 2 GeSnF 6 and 3.12 eV Cs 2 GeSnF 6 . According to an in-depth examination of the optoelectronic features, A 2 GeSnF 6 (A = K, Rb, and Cs), double perovskites are assuring contenders for optoelectronic devices due to their suitable bandgap. The extremely high figure of merit values (0.94-0.97) obtained from the numerical calculation of power factor and thermal conductivity suggest the intriguing prospects of these compositions for thermoelectric devices. These studies offer a perceptive comprehension of the materials for their potential applications in the future., (© 2024. The Author(s).)

The investigation of binary and filled skutterudite structures, particularly PtSb 3 and GdPt 4 Sb 12 , has gained significant attention, becoming a focal point in scientific research. This comprehensive report delves into the intrinsic characteristics of these structures using Density Functional Theory (DFT). Initially, we assess the structural stability of PtSb 3 and GdPt 4 Sb 12 by examining their total ground state energy and cohesive energy, employing the Brich Murnaghan equation of state to determine stability in various configurations. Further insights are gained by exploring second-order elastic constants (SOEC's) to extend our understanding of structural stability. The electronic structures are then meticulously defined through a quantum mechanical treatment, employing a combination of two distinct spin-polarized approximation schemes: Perdew-Burke-Ernzerhof Generalised Gradient Approximation (PBE-GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ). The resulting band structures reveal a symmetry in electronic behavior, showcasing spin-magnetic moments of 3 μB and 7.58 μB per formula unit, with the primary contributions emanating from the Pt 3d and Pt 4+ 3d-transition elements. To gauge thermal stability, we evaluate the phonon-dependent Grüneisen parameter ( γ ) across specific temperature ranges. The study extends to exploring transport properties as a function of chemical potential ( μ - E F ) at various temperatures. The findings suggest that these designed materials hold substantial potential for diverse applications, particularly in conventional spin-based and thermoelectric technologies. The comprehensive insights obtained through this investigation pave the way for a deeper understanding and broader implications in various technological domains., Competing Interests: All authors declare that no known financial or personal interest has been involved that may come forward at a later stage to influence the work reported in this manuscript., (This journal is © The Royal Society of Chemistry.)

Here, we present systematic investigation of the structural and mechanical stability, electronic profile and thermophysical properties of f-electron based XNPO 3 (X = Na, Cs, Ca, Ra) perovskites by first principles calculations. The structural optimization, tolerance factor criteria depicts the cubic structural stability of these alloys. Further, the stability of these materials is also determined by the cohesive and formation energy calculations along with mechanical stability criteria. The electronic structure is explored by calculating band structure and density of states which reveal the well-known half-metallic nature of the materials. Further, we have calculated different thermodynamic parameters including specific heat capacity, thermal expansion, Gruneisen parameter and their variation with temperature and pressure. The thermoelectric effectiveness of these materials is predicted in terms of Seebeck coefficient, electrical conductivity and power factor. All-inclusive we can say that calculated properties of these half-metallic materials extend their route in spintronics, thermoelectric and radioisotope generators device applications., (© 2024. The Author(s).)

By using density functional theory, we have explored the structural, electro-mechanical, thermophysical and thermoelectric properties of CoZrSi and CoZrGe Heusler alloys. The ground state stability was determined by optimising the energy in various configurations like type I, II, and III. It was found that these alloys stabilized in the ferromagnetic phase in type I. We employed the Generalised Gradient Approximation and modified Becke-Johnson potentials to explore the electronic structure. The band structures of each of these Heusler alloys exhibit a half-metallic nature. Additionally, the computed second-order elastic parameters reveal their ductile nature of them. To understand the stability of the alloys at different pressures and temperatures, we investigated various thermodynamic parameters using the Quasi-Harmonic Debye model. We obtained the transport coefficients using the Boltzmann theory. Our findings indicate that these alloys can be used in spintronics and thermoelectric domains., (© 2023. The Author(s).)

Through intricate calculations, the density functional theory (DFT) implemented in the Wien2k code was employed to comprehensively investigate a wide range of material characteristics. Our study encompasses an exhaustive analysis of structural stability, electronic properties, magnetic behaviors, transport phenomena, mechanical responses, and thermodynamic profiles of two notable instances of filled Skutterudites, namely, CeNi 4 P 12 and DyCo 4 Sb 12 , which have been thoroughly explored. These computations were performed using the WIEN 2K code, combining local orbitals and the full-potential linearized augmented plane-wave approach. The findings provided insight into the wide range of properties of these materials. In this methodology, the exchange-correlation potential relies on the local-density approximation. We conducted the calculations with and without incorporating spin-orbit interactions. The results obtained provide information about the lattice constant, bulk modulus, and pressure derivative. The stability, as indicated by the P-V graphical plot, suggests that there are no structural phase transitions from the cubic symmetry structure. Notably, our work includes an examination of Curie temperatures, which are pivotal in understanding magnetic phase transitions. The validated elastic properties further support the material's stability and corroborate its ductile nature. These alloys should be considered for spintronic and thermoelectric applications due to their estimated transport characteristics and the observed ductile nature. To enhance our understanding of the thermal stability of antimony-based compounds, we have made reliable estimations of the thermophysical characteristics. By integrating theoretical insights with practical implications, we bridge the gap between fundamental understanding and material design applications. Using DFT in the Wien2k framework, we discover connections and patterns among different properties, showing how to create materials with specific functions and better performance. This approach not only advances our fundamental comprehension of materials but also promises innovation across various technological domains., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

We conducted a comprehensive analysis of the fundamental properties of CoHfSi and CoHfGe half-Heusler alloys using density functional theory simulations implemented in Wien2k. To begin, structural optimization revealed that both alloys effectively adopt a cubic C 1b structure, with Y1 as the dominant ferromagnetic phase. Electronic properties were computed using various approximation schemes, including the Generalized Gradient Approximation and the modified Becke-Johnson potential. The examination of electronic band structures and their accompanying density of states using the modified Becke-Johnson functional approach unveiled their half-metallic nature. In this context, the spin-up channel exhibited semiconductor behaviour, while the spin-down channel displayed metallic characteristics. Additionally, the spin-splitting observed in their resulting band structures contributed to a net magnetism within their lattice structure, making them promising candidates for spintronic applications. We also scrutinized Seebeck coefficients, electrical conductivity, thermal conductivity, and power factor to gain a better understanding of their thermoelectric properties., Competing Interests: There are no conflict to declare., (This journal is © The Royal Society of Chemistry.)

Here, we investigated the structural, mechanical, electronic, magnetic, thermodynamic and thermoelectric properties of Strontium based simple perovskites SrMO 3 (M = Pa, Np, Cm, Bk) by using density functional theory. First and foremost, the ground state stability of these perovskites was initially evaluated by optimizing their total ground state energies in distinct ferromagnetic and non-magnetic configurations. The structural stability in terms of their ground state energies defines that these alloys stabilize in ferromagnetic rather than competing non-magnetic phase. From the understandings of mechanical parameters these alloys are characterized to be ductile in nature. After that, two approximation schemes namely Generalized Gradient approximation and Tran-Blaha modified Becke-Johnson potential have been used to find their intimate electronic structures which displays the half-metallic nature of these alloys. Further, we have verified temperature and pressure effect on these alloys. Finally, the transport properties have been evaluated within the selected temperature range of 150-900 K. In view of this, the different transport parameters along with half-metallic nature advocate their possible applications in thermoelectric and spintronics devices., (© 2023. Springer Nature Limited.)

Using the density functional theory methodology, we have thoroughly examined KRu 4 As 12 and KRu 4 Sb 12 skutterudites, including their structural, electronic, mechanical, transport, and thermodynamic properties. First and foremost, using the Birch-Murnaghan equation of state, the structural stability has been calculated in terms of their total ground state and cohesive energies. With the use of the approximation approaches GGA and GGA + mBJ, the electrical structure and density of the states reveal their metallic nature. This demonstration predicts the dominant ferromagnetic spin configuration of materials by considering their electronic behavior and magnetic interactions. The ductile behavior of these alloys is also addressed by their mechanical qualities, which indicate how they might be used in engineering and industrial settings. Moreover, the semi-classical Boltzmann transport theory has been employed to examine the Seebeck coefficient as well as the electric and thermal conductivities. The general tendency of these compounds demonstrates their various potential uses as electrode materials. The quasi-harmonic Debye approximation is a method used to analyze the stability of a system under high pressures and accounts for the temperature dependency of thermodynamics. It combines the quasi-harmonic approximation, which considers the anharmonicity of vibrations, with the Debye model, which describes the vibrational modes of a solid. This approach allows for a more accurate representation of the system's behavior at different temperatures and pressures. By implementing this approximation, researchers can gain insights into the stability and thermodynamic properties of materials under extreme conditions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The structural stability, optoelectronic and magnetic characteristics of K 2 NaMI 6 (M = Mn, Co, and Ni) halide double perovskites have been demonstrated to be explained using density functional theory computations. The prominent generalized gradient approximation and integration of the mBJ potential are implemented to estimate the exchange-correlation potential, which is the only unidentified parameter in the state-of-the-art formulism. The structural optimization, mechanical stability criteria, and tolerance factor demonstrate the reliability of the double perovskites in a cubic structure with Fm3m symmetry. The elastic constants facilitated mechanical stability and revealed the brittle nature of these double perovskites. The spin-polarized electronic band profile and the behaviour of the dielectric constant and absorption coefficient in the spin-up and down channels show the presence of half-metallic nature in these materials. Additionally, we examined magnetism and the genesis of the half-metallic gap in this article. The half-metallic and magnetic properties are attributed to the unpaired electrons in the split d-orbitals of the M-sited elements in the crystal field. The Mn-, Co-, and Ni-based double perovskites were found to possess total magnetic moments of 4 μB, 4 μB, and 1 μB, respectively, with the transition metal atoms comprising up the majority of this magnetic moment. The Fermi level's perfect spin polarisation promotes the potential application of double perovskites in spintronic technology., (© 2023. Springer Nature Limited.)

Herein, we have first reported the intrinsic properties, including structural, mechanical, electronic, magnetic, thermal, and transport properties of XTiBr 3 (X = Rb, Cs) halide perovskites within the simulation scheme of density functional theory as integrated into Wien2k. First and foremost, the structural stability in terms of their ground state energies has been keenly evaluated from their corresponding structural optimizations, which advocate that XTiBr 3 (X = Rb, Cs) has a stable ferromagnetic rather than the competing non-magnetic phase. Later on, the electronic properties have been computed within the mix of two applied potential schemes like Generalized Gradient Approximation (GGA) along with Trans-Bhala modified Becke Johnson (TB-mBJ), which thoroughly addresses the half-metallic behaviour with spin-up as metallic and in contrast to opposite spin-down channel signatures the semiconducting behaviour. Furthermore, the spin-splitting seen from their corresponding spin-polarised band structures offers a net magnetism of 2 µB which lends their opportunities to unlock the application branch of spintronics. In addition, these alloys have been characterised to show their mechanical stability describing the ductile feature. Moreover, phonon dispersions decisively certify the dynamical stability within the density functional perturbation theory (DFPT) context. Finally, the transport and thermal properties predicted within their specified packages have also been forwarded in this report., (© 2023. The Author(s).)

Heusler alloys have drawn the interest of researchers due to their possible technical significances and multifunctional use. Herein, a thorough theoretical analysis using "density functional theory (DFT)" is performed to investigate the general physical features of RbTaSi and RbTaGe alloys. The "generalised gradient approximation (GGA)" and "Tran-Blaha modified Becke-Johnson (TB-mBJ) potential" has been incorporated to model the electronic structures of RbTaSi and RbTaGe. The structural optimization results signify that these materials are stable in the ferromagnetic phase with a cubic F 4̄3 m structure, which is supported by the computed elastic parameters. In addition, cohesive energy and microhardness signify strong bonding. The spin-polarisation bands and density of states indicate the half-metallic nature of these materials. These materials have spin magnetic moment 2μ B , thereby emphasizing the use of these alloys for spintronic applications. Transport and thermodynamic properties have been calculated, and their temperature dependence is illustrated. The behavior of transport coefficients with temperature futher implies the presence of half-metallic nature., Competing Interests: There is no conflict of interest among the authors., (This journal is © The Royal Society of Chemistry.)

Since the unexpected accelerated discovery of half-metallic perovskites is continuously on the rise both from basic sciences and application-oriented sides. Herein, for the first time in this carried research work, we significantly delivered a detailed analysis on one of experimentally synthesized perovskite structure Ba 2 ErNbO 6 and in related to Ba 2 TmNbO 6 within the realm of unified density functional theory. Initially, the structural stability of two molecular perovskite structures were critically established interms of their total ground state and cohesive energies by the expendition of Brich Murnaghan equation of state. Also, the tolerance factor (τ) oversees the cubic structural stability without possessing any geometrical strains. More likely, the density functional perturbation theory (DFPT) has been calibrated to perceive the dynamical context of these layered structures. Also, from the understandings of second order elastic and mechanical parameters adresses their suitable ductile characteristics. The quantum mechanical refinement of their intrinsic electronic structures were systematically tuned by the exploitation of Generalised gradient approximation (GGA), on-site Hubbard scheme (GGA + U) selected to the strongly correlated electrons of particular angular momentum and modified Becke-Johnson (mBJ) potential. Moreover, the two-dimensional representation of asymmetric density of states (DOS) pinned around the Fermi-level (E F ) and the interpretation linked to their corresponding spin-polarised band structures signatures the well-known half-metallic nature. Subsequently, the transport properties especially the value of figure of merit ( Z T) equals to unity (1) along the selected chemical potential range at different temperatures. The summed-up properties and the overall tendency triggers the possibility of these materials to register their extending applications in spintronics, thermoelectrics, nanoengineering, and radioisotope generator perspectives., (© 2022. The Author(s).)

In the hunt for novel materials, we present self-consistent ab initio simulations of the structural stability, electronic profile, and transport properties of f-electron-based RbMO 3 (M = Np, Pu) perovskites within the context of density functional theory. The structural stability and thermodynamic concerns are fixed by relaxing the crystal structure and computing the energy of formation, respectively. Furthermore, the decisive physical features of given materials have been outlined using the optimised lattice constant retrieved from structural optimizations. The ground state magnetic phase stability is ascertained by minimizing Birch Murnaghan's equation of state in distinct magnetic phases, upholding the ferromagnetic phase (FM) as the ground state magnetic phase, which is further backed by positive Curie Wiess constant values. To specify the electronic structure, a mix of the two approximations GGA and GGA + mBJ has been executed, both of which assert the half-metallic character, culminating in 100% spin polarisation at the Fermi level. The study of the magnetic moment and Curie temperature of each material has further been assessed in the present study. Apart from half-metallicity, the thermoelectric response of the present materials is quantified by exploring the chemical potential dependency of several transport parameters like Seebeck coefficient, electrical and thermal conductivity, power factor, etc. Moreover, the thermoelectric competence has been tested using a zT calculation, adapting values of 1.01 and 0.987 at 300 K for RbNpO 3 and RbPuO 3 , respectively. The high electronic zT at encompassing temperatures uncovers the significant utility of these materials in both low-and high-temperature thermoelectric device applications. In essence, the comprehensive survey of these alloys could certainly open up their possibilities in spintronics, thermoelectric, and solid-state (RTG) device applications., (© 2022. The Author(s).)

Self-consistent DFT-based structural optimizations for understanding the cation effect on various properties of A 2 SnFeO 6 (A = Ca, Ba) perovskites have been figured out in this study. The two-dimensional spin-polarized band structures, along with their corresponding density of states within the mix of two calculation schemes Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA) and Hubbard correlation correction (PBE + U ), strongly appeals its half-metallic nature, which has been discussed in detail. The perfect occurrence of the half-metallic nature with high-spin subsystem corresponds to a metal-type spectrum and in contrast to the opposite-spin claims semiconducting behaviour. The effect of significant spin-polarisation creates a ferromagnetism of total 4 ( μ B ) mostly arising at (Fe). The induced magnetism of oxygen atoms is due to the overlapping between Fe-3d-O-2p orbitals. The mechanical strength is characterized from cubic elastic parameters that decide the capability of these materials against various external distortion forces displaying brittle nature. Apart from this, the semi-classical Boltzmann transport theory embedded in BoltzTraP package has been keenly addressed to turn out Seebeck coefficients, electrical and lattice thermal conductivities. The overall study creates a significant momentum in connection with the development of unlocking spintronics, spin dynamics and energy harvesting applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Explorations of stable lead-free perovskites have currently achieved substantial interest to overcome the instability and avoid toxicity related issue faced with the lead-based perovskites. In this study, we have comprehensively studied the stability, nature and origin of electronic, transport and optical properties of inorganic halide double perovskites, which could provide a better understanding of their possible potential applications. The density functional theory is used to investigate the different physical properties of these materials. The stability of these cubic materials is validated by optimizing the structure, tolerance factor, mechanical stability test. The materials are small band gap semiconductors with outshining optoelectronic performance. Due to high optical absorption, high conductivity and low reflectivity they have great potential to be used for optoelectronic application purpose. Because of small band gap we have also investigated the variation of various transport parameters with chemical potential. The semiconducting nature of materials results in ZT close to unity predicting its excellent application in thermoelectric technology.

Through the conventional DFT computation, we have designed new oxide double perovskites Ba 2 FeNiO 6 and Ba 2 CoNiO 6 . The structural and thermodynamic stabilities are predicted by optimizing the crystal structure and evaluation of enthalpy of formation, respectively. Then by using the optimized lattice constant, we have explored the different physical properties. The GGA + mBJ electronic band-structure illustrates Ba 2 FeNiO 6 is a half-metal with 100% spin polarization at the Fermi level. While Ba 2 CoNiO 6 shows a ferromagnetic semiconducting nature. The change in the electronic structure when Fe is replaced by Co is explained with the help of the orbital diagram and exchange interaction. The e g -e g hybridization that happens via O-p states is strong because Fe-O-Ni and Co-O-Ni bond angles are strictly 180°. The narrow bandgaps in the semiconducting channels prompted us to analyze the applicability of these materials towards thermoelectric technology. Besides this, we have investigated the dependency of transport properties on electronic band structure. The semiconducting nature in Ba 2 CoNiO 6 results in a significant ZT around 0.8 at room temperature makes it suitable for wasted-energy regeneration.

The hunt for high spin polarization and efficient thermoelectric materials has endured for decades. In this paper, we have explored the structural, mechanical stability, magneto-electronic, and thermoelectric properties of two new quaternary Heusler alloys, CoNbMnZ (Z = Ge, Sn), using first-principles simulation methods. The alloys are stable, showing a Y 1 -type phase and ferromagnetic nature. Based on a generalized gradient approximation method, the alloys exhibit metallic nature; upon employing a modified version of the Becke-Johnson potential, both alloys demonstrate half-metallic nature, with gaps of 0.43 and 0.45 eV, which is a precursor for high spin polarization in these alloys. The alloys also follow the necessary Slater-Pauling rule condition M T = Z T - 24 for half-metallicity and they have a total magnetic moment of 1 μ B . Elastic parameters convey the mechanical stabilities of these alloys, with Debye temperatures of 518 K and 445 K. These materials act as anisotropic media with respect to longitudinal and transverse sound velocities. Possible energy efficiency and thermoelectric applications were scrutinized via computing Seebeck coefficients, electrical and electronic lattice thermal conductivities, and, lastly, power factors. The highest S values for Ge- and Sn-based alloys are 60.43 and 68.2 μV K -1 , respectively, and the highest power factors are 32 and 35 μW K -2 cm -1 , respectively, suggesting potential efficient applications in thermoelectric power generation., Competing Interests: The authors hereby declare that we have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Herein, first principles computer-based simulations were performed to predict the ground-state structure, mechanical stability, and magneto-electronic properties of BaMO 3 (M = Mg and Ca) perovskites, which have not been experimentally synthesized to date. Structural optimization authenticate the stability in the cubic structure for BaMO 3 perovskites having symmetry of the Pm 3 m space group. The tolerance factor and cohesive energy further validate the stability of BaMO 3 in the cubic phase. Moreover, mechanical stability was confirmed by the positive elastic constants, satisfying the necessary stability conditions. The band structure and density of states at the optimized lattice constants revealed the ferromagnetic half-metallic character of BaMO 3 materials, with O-p states playing a prominent role. The half-metallic character originates from the partial filling of the O-p states in the spin-down channel. Spatial charge distribution indicated the dominant ionic character of bonding. No change in the magnetic moment of perovskites was observed upon changing the M-site atoms. Various elastic parameters suggested that these perovskites are ductile in nature with highly anisotropic character. The three-dimensional graphical representation of different elastic moduli revealed that the linear compressibility is isotropic, whereas the shear modulus, Young's modulus, and Poisson's ratio of these perovskites are highly anisotropic. The results obtained in this study are in agreement with those reported in the literature for other similar perovskites., Competing Interests: The authors declare that they have no conflict of interest for this work., (This journal is © The Royal Society of Chemistry.)

A cohesive study using density functional theory simulations is performed to reveal and understand the structural stability, optoelectronic and magnetic properties of Cs 2 NaMCl 6 (M = Mn, Co and Ni) halide double perovskites. The exchange-correlation potential, which is the only unknown parameter in the state-of-the-art formulism is determined through the well-known generalized gradient approximation and integration of the mBJ potential to it. The structural optimization, mechanical stability criteria and tolerance factor confirmed the stability of the double perovskites in a cubic structure with Fm 3̄ m symmetry. The elastic constants endorsed the mechanical stability and justify the brittle character of these double perovskites. The spin polarized electronic band profile and behaviour of the dielectric constant and absorption coefficient in the spin up and down channels revealed the presence of half-metallic nature in these materials. Moreover, herein, we have discussed the origin of the half-metallic gap and magnetism. The unpaired electrons in the crystal field splitted d-orbitals of the M-sited constituents are responsible for the half-metallic and magnetic character. The total magnetic moment was determined to be 4 μ B , 4 μ B and 1 μ B for the Mn-, Co- and Ni-based double perovskites, respectively, with main contributions solely coming from the transition metal atoms. The perfect spin polarization at the Fermi level suggests the application of double perovskites in spintronic technology., Competing Interests: The authors have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The structural, electronic, optical, thermodynamic and thermoelectric properties of double perovskites Ba 2 MTaO 6 (M = Er, Tm) have been studied. These alloys stabilize in cubic structure with paramagnetic phases and structural parameters that are in good agreement with experimental results. The elastic parameters reveal both materials as being super hard and brittle in nature. The band profile displays the direct bandgap semiconducting behavior of both compounds in the spin-up channels. The optical coefficients, viz. optical conductivity, reflectivity and electron energy loss, are intended for a photon energy of up to 14 eV to perceive the optical response. The effects of temperature and pressure on the thermodynamic properties have also been evaluated via the quasi-harmonic Debye model. Post-DFT treatment was performed to explore the thermoelectric properties; both perovskites exhibit a colossal power factor of 90 × 10 11 W m -1 K -2 s -1 and 5 × 85 × 10 11 W m -1 K -2 s -1 for Ba 2 TmTaO 6 and Ba 2 ErTaO 6 , respectively, at 800 K., Competing Interests: The authors have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The structural and mechanical stability of Fe 2 TaAl and Fe 2 TaGa alloys along with the electronic properties are explored with the help of density functional theory. On applying different approximations, the enhancement of semiconducting gap follows the trend as GGA < mBJ < GGA + U. The maximum forbidden gaps observed by GGA + U method are E g  = 1.80 eV for Fe 2 TaAl and 1.30 eV for Fe 2 TaGa. The elastic parameters are simulated to determine the strength and ductile nature of these materials. The phonon calculations determine the dynamical stability of all these materials because of the absence of any negative frequencies. Basic understandings of structural, elastic, mechanical and phonon properties of these alloys are studied first time in this report.

We have computed the electronic structure and transport properties of Fe 2 TaZ (Z = Al, Ga, In) alloys by the full-potential linearized augmented plane wave (FPLAPW) method. The magnetic conduct in accordance with the Slater-Pauling rule classifies them as non-magnetic alloys with total zero magnetic moment. The semiconducting band profile and the density of states in the post DFT treatment are used to estimate the relations among various transport parameters such as Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit. The Seebeck coefficient variation and band profiles describe the p-type behavior of charge carriers. The electrical and thermal conductivity plots follow the semiconducting nature of bands along the Fermi level. The overall measurements show that semi-classical Boltzmann transport theory has well-behaved potential in predicting the transport properties of such functional materials, which may find the possibility of their experimental synthesis for future applications in thermoelectric technologies., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Density functional theory (DFT)-based investigations have been put forward on the elastic, mechanical, and thermo-dynamical properties of BaPaO 3 . The pressure dependence of electronic band structure and other physical properties has been carefully analyzed. The increase in Bulk modulus and decrease in lattice constant is seen on going from 0 to 30 GPa. The predicted lattice constants describe this material as anisotropic and ductile in nature at ambient conditions. Post-DFT calculations using quasi-harmonic Debye model are employed to envisage the pressure-dependent thermodynamic properties like Debye temperature, specific heat capacity, Grüneisen parameter, thermal expansion, etc. Also, the computed Debye temperature and melting temperature of BaPaO 3 at 0 K are 523 K and 1764.75 K, respectively.

The structural, elastic and electronic properties of lutatium-pnictides (LuN, LuP, LuAs, LuSb, and LuBi) were analyzed by using full-potential linearized augmented plane wave within generalized gradient approximation in the stable rock-salt structure (B1 phase) with space group Fm-3m and high-pressure CsCl structure (B2 phase) with space group Pm-3m. Hubbard-U and spin-orbit coupling were included to predict correctly the semiconducting band gap of LuN. Under compression, these materials undergo first-order structural transitions from B1 to B2 phases at 241, 98, 56.82, 25.2 and 32.3 GPa, respectively. The computed elastic properties show that LuBi is ductile by nature. The electronic structure calculations show that LuN is semiconductor at ambient conditions with an indirect band gap of 1.55 eV while other Lu-pnictides are metallic. It was observed that LuN shows metallization at high pressures. The structural properties, viz, equilibrium lattice constant, bulk modulus and its pressure derivative, transition pressure, equation of state, volume collapse, band gap and elastic moduli, show good agreement with available data.

Fully relativistic pseudo-potential ab-initio calculations have been performed to investigate the high pressure phase transition, elastic and electronic properties of lead-chalcogenides including the less known lead polonium. The calculated ground state parameters, for the rock-salt structure show good agreement with the experimental data. PbS, PbSe, PbTe and PbPo undergo a first-order phase transition from rock-salt to CsCl structure at 19.4, 15.5, 11.5 and 7.3 GPa, respectively. The elastic properties have also been calculated. The calculations successfully predicted the location of the band gap at L-point of Brillouin zone and the band gap for each material at ambient pressure. It is observed that unlike other lead-chalcogenides, PbPo is semi-metal at ambient pressure. The pressure variation of the energy gap indicates that these materials metalize under pressure. The electronic structures of these materials have been computed in parent as well as in high pressure B2 phase.

The pressure-induced crystal properties of Eu chalcogenides were investigated using two different models: a modified charge-transfer potential model consisting of Coulomb screening due to the delocalization of the f electron of the rare earth atom, and modified by covalency and zero-point energy effects along with attractive and repulsive interactions; and a charge-transfer model that excluded the covalency and zero-point energy effects in the previous model. Both models were used to visualize the effect of covalency on the mechanism of interaction of the constituent atoms. Eu chalcogenides transform from the Fm3m to the Pm3m phase under the influence of sufficient pressure (P(T) = 39.52, 21.01, 14.31, and 10.58 GPa), and their equations of state indicated decreases in volume during this phase transition of 6.38, 12.32, 12.76, and 11.15%, respectively, for EuO, EuS, EuSe, and EuTe. The results obtained from the models were in good agreement with corresponding experimental data. The elastic constants and Debye temperatures were also computed at normal and high pressures. Both of the models were found to be capable of successfully explaining these properties.

The pressure induced structural and mechanical properties of nanocrystalline ZnO, ZnS, ZnSe, GaN, CoO, CdSe, CeO(2), SnO(2), SiC, c-BC(2)N, and β-Ga(2)O(3) with different grain sizes have been analyzed under high pressures. The molecular dynamics simulation model has been used to compute isothermal equation of state, volume collapse and bulk modulus of these materials in nano and bulk phases at ambient and high pressures and compared with the experimental data. It is evident from these calculations that the change in particle size affects directly the phase transition pressure and bulk modulus. The values of phase transition pressure and bulk modulus increase with decrease in grain size of the material. The equilibrium cell volume and volume collapse in parent phase is directly proportional to the grain size of the materials. Present results are in good agreement with experimental data. The model is able to explain these thermodynamic properties at varying temperatures and pressures successfully.