First-principles calculations of the stability and electronic properties of KHn under pressure

Calcium carbonate (CaCO3) is an inorganic compound which is widely used in industry, chemistry, construction, ocean acidification and biomineralization due to its rich constituent on earth and excellent performance, in which calcium carbonate hydrates are important systems. In Z.Y. Zou et al’s work (Science, 2019, 363, 396–400), they found a novel calcium carbonate hemihydrate phase, but the structure stability, optical and mechanical properties has not been studied. In this work, the stability, electronic, optical, and mechanical properties of novel calcium carbonate hydrates were investigated by using the first-principles calculations within density functional theory (DFT). CaCO3·xH2O (x=1/2, 1 and 6) are determined dynamically stable phases by phonon spectrum, but the Gibbs energy of reaction of CaCO3·1/2H2O is higher than other calcium carbonate hydrates. That’s why the CaCO3·1/2H2O is hard to synthesize in the experiments. In addition, the optical and mechanical properties of CaCO3·xH2O (x=1/2, 1 and 6) are expounded in detail. It shows that the CaCO3·1/2H2O has the largest bulk modulus, shear modulus, Young’s modulus with the values 60.51, 36.56 and 91.28 GPa with respect to other two calcium carbonate hydrates investigated in this paper. This work will provide guidance for experiments and its applications, such as biomineralization, geology, and industrial processes.

A hydrothermal method is considered to be convenient and is extensively used in preparing titanate architectures, but the intermediate and final products are complicated and variable. To date, it is accepted that intermediates are tri- and hexatitanates. Here, atomic structures, energetics, and correlations between stability and electronic properties of proton exchange in tri- and hexatitanates, i.e., Na2-xHxTi3O7 and Na2-xHxTi6O13, are investigated by first-principles calculations. We found that the bond length of Na-O bonds plays a significant role in determining the activity of tunnel oxygen atoms, while the proton substitution sites are closely related to the activity of tunnel O atom in titanates. As H+ concentration increases, the formation energy of Na2-xHxTi3O7 and Na2-xHxTi6O13 decreases first and then increases, suggesting that completely protonated titanates, i.e., H2Ti3O7 and H2Ti6O13, are unstable. However, we found that H+ substitution would take place even in an alkaline solution both for Na2Ti3O7 and Na2Ti6O13. With a decrease in the pH, the process of H+ exchange becomes more energetically favorable. Compared to Na2Ti3O7, Na+ ions are more easily exchanged by H+ ions in Na2Ti6O13 at the same pH value. We found that there is a strong correlation between stability and electronic properties during the Na+-H+ exchange process. Finally, hydrogen bonds are observed in H2Ti3O7 and Na2-xHxTi6O13 complexes, which make them more stable than Na2-xHxTi3O7 complexes without H-bonds. All of these findings provide insight into understanding the geometry of possible intermediates in the preparation of titanates and suitable conditions for the synthesis of titanates.

First-principles investigation of structural, mechanical and electronic properties for Cu–Ti intermetallics

This study presents a theoretical investigation into the phase stability, electronic, and optical properties of off-stoichiometric Zr_{x}Ti_{1-x}IrSb (x = 0, 0.0625, 0.1875, 0.25, 0.50, 0.75, 1) compounds. Using first-principles calculations, we explore how varying Zr and Ti concentrations can tune the electronic and optical properties of these half-Heusler alloys. The Structural, optical, and electronic properties were meticulously analyzed with both the GGA-PBE and Meta-GGA-SCAN approximations, as implemented in the Vienna Ab initio Simulation Package (VASP). The dynamical stability of these compounds was assessed using the Phonopy package. Our findings reveal that these alloys exhibit semiconductor behavior with tunable band gaps, and their optical properties show significant variation across different compositions, particularly in the visible light range. The compounds also demonstrate robust dynamical stability, indicating their potential for practical applications in electronic and optoelectronic devices. These results underscore the versatility of Zr_{x}Ti_{1-x}IrSb alloys and highlight their promise for next-generation technology.

The electronic structure, elastic properties, dynamical stability and thermoelectric properties of rock-salt and orthorhombic phases of CdS: First-principles calculations

Crystal structures, stability, electronic and elastic properties of 4d and 5d transition metal monoborides: First-principles calculations

Exploring phase stability, electronic and mechanical properties of Ce–Pb intermetallic compounds using first-principles calculations

First-principles prediction on the structural stability, electronic and mechanical properties of TixBy phases

Investigation of Iron-based double perovskite oxides on the magnetic phase stability, mechanical, electronic and optical properties via first-principles calculation

Electronic structure, phase stability, vibrational and thermodynamic properties of the ternary Nowotny-Juza materials LiMgSb and LiZnSb

The stability, electronic and optical properties of nonmetal doped g-GaN: A first-principles calculation

Theoretical prediction on stability, electronic and activity properties of single-atom catalysts anchored graphene and boron phosphide heterostructures

Nobel-metal based bimetallic nanoparticles (BNPs) are composed of two different metals presenting heteroatom interactions. In these nanomaterials it is possible to tune the relative composition that allows for the modulation of electronic and catalytic properties. They are of great interest for their technological and industrial applications due to their catalytic properties which may exceed those of their monometallic analogue structures. A theoretical perspective on the electronic, stability and reactivity related properties of gold, ruthenium and Au-Ru nanoparticles is presented herein. This analysis considered the use of first-principles methods and the cluster approach to get a physical insight into the novel properties that arise from the combination of two metals in the nano and sub-nano scale. Au-Ru BNPs may present a higher catalytic efficiency than the monometallic structures due to the synergy between the metals in the CO oxidation reaction. However, the effect of Ru over the Au-based NPs on their enhanced catalytic activity is not well understood. A density functional theory (DFT) study of one Au-Ru cluster model was performed to analyze its electronic properties and to gain a better understanding in the stability of structures with various metal compositions. Based on the computed mixing enthalpy, the Au-Ru cluster with a core-shell type morphology and a relative composition close to 1:0.75 was determined as the most stable one. Finally, a CO oxidation reaction pathway different from that determined for Au-NPs was presented for the free particle occurring in the Au-Ru interface. O2 may undergo adsorption on a Ru site through a dissociative process. The computed CO oxidation barrier height is lower than that found for the monometallic Ru clusters but is higher than that determined for Au clusters. This study will guide further research on this kind of model nanostructures in heterogeneous catalysis.

In this study, we explored the structural, electronic, optical, and transport properties of the GaN/perovskite heterostructures using density functional theory combined with non-equilibrium Green’s function calculations. Four interfacial configurations have been studied, and the interfacial properties were discussed on the basis of the optimal theoretical situation. The Ga-polar N-termination interface was found to be the most favorable interfacial configuration, with an interfacial cohesive energy of 0.4 eV/A2, whereas that of the other three heterostructures was less than 0.1 eV/A2. Results showed that the interfacial nitrogen atoms had a significant impact on the structural stability and electronic properties via interfacial hybridizations. Furthermore, the influence of segregated dopants at the interface on device performance was also studied. The interfacial doping strategy proposed in this study demonstrated improved optoelectronic properties. Therefore, these results provide theoretical guidelines for developing high-performance of GaN/perovskite heterostructures in perovskite solar cells. The atomic structure, electronic and optical properties of GaN (0001)/MAPbI3 (110) interfaces with a lattice mismatch less than 3% were analyzed using first-principles calculations.

Stability, electronic and magnetic properties of triangular graphene nanoflakes embedded in graphane (graphane-embedded TGNFs) are investigated by density functional theory. It is found that the interface between the embedded TGNF and graphane is stable since the diffusion of H atoms from the graphane region to the embedded TGNF is energetically unfavorable with high energy barriers. The electronic and magnetic properties of the system completely depend on the embedded TGNF. The band gaps of graphane-embedded ATGNFs (armchair-edged TGNFs) arise due to the quantum confinement, while the special characteristics of nonbonding states of graphane-embedded ZTGNFs (zigzag-edged TGNFs) play an important role in their electronic properties. As the edge sizes increase, the differences of band gaps between graphane-embedded TGNFs and the isolated ones decrease. Furthermore, owing to the partially paired p(z) orbitals of edge C atoms, graphane-embedded ZTGNFs exhibit a ferrimagnetic ground state with size-dependant total spin being consistent with Lieb's theorem. Our work provides a possible way to obtain TGNFs without physical cutting.