Codoped germanene with 3p and 4p elements elements.

Context: The relentless need for new materials to be used in electronic devices has opened new research directions in materials science. One of them involves using two-dimensional materials, among which there is current interest in using germanene. The heteroatom doping of germanene has been proposed as a possible approach to fine-tuning its electronic properties.

Novel Janus gamma-Pb XY monolayers with high thermoelectric performance X=S, Se and Y=Se, Te X Y.

The quest for efficient thermoelectric materials has intensified with the advent of novel Janus monolayers exhibiting exceptional thermoelectric parameters. In this work, we comprehensively investigate the structural, electronic, transport, phonon, and thermoelectric properties of novel Janus -Pb XY (X=S, Se; Y=Se, Te; X Y) monolayers using density functional theory combined with the Boltzmann transport equation. Our findings unveil the energetic, dynamic, thermal, and mechanical stability of these monolayers, along with their remarkable thermoelectric performance.

Covalent functionalization of germanene employing computational simulations.

Computational simulations through density functional theory in conjunction with M06-L and HSE functional have been carried out to investigate the chemical reactivity of the germanene monolayer. It is exceptionally reactive, with an average reaction energy of -60.4 kcal mol for the nineteen functional groups considered: H, F, Cl, Br, O, S, Se, Ge, OH, SH, CH, CF, NH, NH, CH, CH, CCl, CBr, and the azomethine ylide.

Theoretical Characterization of Germanene Doped with Main Group Elements.

Herein, using density functional calculations, we studied the substitutional doping in germanene with B, C, N, O, Al, Si, P, S, Ga, As, and Se. Nitrogen is the element that can be more easily incorporated into the germanene lattice, followed by silicon, carbon, and boron. Almost all dopants were efficient in opening a band-gap.

Novel octa-graphene-like structures based on GaP and GaAs.

Context: The discovery of graphene gave way to the search for new two-dimensional structures. In this regard, octa-graphene is a carbon allotrope consisting of 4- and 8-membered rings in a single planar sheet, drawing the research community's attention to study their inorganic analogs. Considering the promising properties of octa-graphene-like structures and the role of GaAs and GaP in semiconductor physics, this study aims to propose, for the first time, two novel inorganics buckled nanosheets based on the octa-graphene structure, the octa-GaAs and octa-GaP.

TopIso3D : Enhancing Topological Analysis through 3D Isosurfaces.

We present TopIso3D , a software with a user-friendly graphical interface, that generates three-dimensional maps to analyze descriptors based on the Quantum Theory of Atoms in Molecules (QTAIM), applied in periodic and nonperiodic systems. The software also automates the launching of topological analysis calculations through the Topond package and generates a report that facilitates the identification of the values of the calculated descriptors, in the Bond Critical Points (BCP) and Critical Points of the Laplacian of the electron density (LCP), facilitating the classification of chemical interactions. The map projects created can be stored in the form of HTML files, for later consultation through any type of browser.

Modeling of BN-Doped Carbon Nanotube as High-Performance Thermoelectric Materials.

Ternary BNC nanotubes were modeled and characterized through a periodic density functional theory approach with the aim of investigating the influence on the structural, electronic, mechanical, and transport properties of the quantity and pattern of doping. The main energy band gap is easily tunable as a function of the BN percentage, the mechanical stability is generally preserved, and an interesting piezoelectric character emerges in the BNC structures. Moreover, C@(BN)C double-wall presents promising values of the thermoelectric coefficients due to the combined lowering of the thermal conductivity and increase of charge carriers.

Unconventional Disorder by Femtosecond Laser Irradiation in FeO.

This paper demonstrates that femtosecond laser-irradiated FeO materials containing a mixture of α-FeO and ε-FeO phases showed significant improvement in their photoelectrochemical performance and magnetic and optical properties. The absence of Raman-active vibrational modes in the irradiated samples and the changes in charge carrier emission observed in the photocurrent density results indicate an increase in the density of defects and distortions in the crystalline lattice when compared to the nonirradiated ones. The magnetization measurements at room temperature for the nonirradiated samples revealed a weak ferromagnetic behavior, whereas the irradiated samples exhibited a strong one.

Ab Initio Modeling of MultiWall: A General Algorithm First Applied to Carbon Nanotubes.

A general, versatile and automated computational algorithm to design any type of multiwall nanotubes of any chiralities is presented for the first time. It can be applied to rolling up surfaces obtained from cubic, hexagonal, and orthorhombic lattices. Full exploitation of the helical symmetry permits a drastic reduction of the computational cost and therefore opens to the study of realistic systems.

Unveiling the Structural Behavior under Pressure of Filled MCoSb (M = K, Sr, La, Ce, and Yb) Thermoelectric Skutterudites.

Skutterudite-type compounds based on □CoSb pnictide are promising for thermoelectric application due to their good Seebeck values and high carrier mobility. Filling the 8 voids (in the cubic space group 3̅) with different elements (alkali, alkali earth, and rare earth) helps to reduce the thermal conductivity and thus increases the thermoelectric performance. A systematic characterization by synchrotron X-ray powder diffraction of different M-filled CoSb (M = K, Sr, La, Ce, and Yb) skutterudites was carried out under high pressure in the range ∼0-12 GPa.

Role of Surfaces in the Magnetic and Ozone Gas-Sensing Properties of ZnFeO Nanoparticles: Theoretical and Experimental Insights.

The magnetic properties and ozone (O) gas-sensing activity of zinc ferrite (ZnFeO) nanoparticles (NPs) were discussed by the combination of the results acquired by experimental procedures and density functional theory simulations. The ZnFeO NPs were synthesized via the microwave-assisted hydrothermal method by varying the reaction time in order to obtain ZnFeO NPs with different exposed surfaces and evaluate the influence on its properties. Regardless of the reaction time employed in the synthesis, the zero-field-cooled and field-cooled magnetization measurements showed superparamagnetic ZnFeO NPs with an average blocking temperature of 12 K.

Intra-octahedral distortion on lamellar potassium niobate KNbO: a periodic DFT study of structural, electronic and vibrational properties.

Structural, electronic and spectroscopic properties of the anhydrous KNbO niobate were investigated in the bulk phase using periodic density functional theory (DFT) calculations with global hybrid (B3LYP) and also including dispersion corrections (B3LYP-D3). The degree of native distortion of different niobium octahedra (here named [NbO], or [NbO]) were quantified in terms of the effective coordination number (ECoN) and of other classical descriptors of local deformation and were correlated with the electronic structure. The effect of intrinsic deformation was also examined using the quantum theory of atoms in molecules and crystals (QTAIMC), density of states and charge analyses.

Probing the Site-Selective Doping in SrSnO:Eu Oxides and Its Impact on the Crystal and Electronic Structures Using Synchrotron Radiation and DFT Simulations.

The impact of Eu doping at the Sr and Sn sites in SrSnO on its structural and electronic properties was studied and correlated with the photocatalytic efficiency. The compounds were synthesized using a modified Pechini method. Refinement of the synchrotron X-ray diffraction (S-XRD) data showed that the samples had an orthorhombic symmetry.

Quantitative evaluation of the surface stability and morphological changes of CuO particles.

CuO low-index surfaces periodic models have been simulated based on density functional theory. The calculated surfaces energies allowed estimating the morphology by means of the Wulff theorem as well as the investigation of possible paths of morphological changes. Therefore, systematic morphology diagrams and change paths according to the energy modulation in relation to the surfaces stabilizations were elaborated.

Piezoelectric Response of Porous Nanotubes Derived from Hexagonal Boron Nitride under Strain Influence.

A computational study via periodic density functional theory of porous nanotubes derived from single-layer surfaces of porous hexagonal boron nitride nanotubes (PBNNTs) and inorganic graphenylene-like boron nitride nanotubes (IGP-BNNTs) has been carried out with the main focus in its piezoelectric behavior. The simulations showed that the strain provides a meaningful improve in the piezoelectric response on the zigzag porous boron nitride nanotubes. Additionally, its stability, possible formation, elastic, and electronic properties were analyzed, and for comparison purpose, the porous graphene and graphenylene nanotubes were studied.

A quantum-mechanical investigation of oxygen vacancies and copper doping in the orthorhombic CaSnO perovskite.

In this study we explore the implications of oxygen vacancy formation and of copper doping in the orthorhombic CaSnO3 perovskite, by means of density functional theory, focusing on energetic and electronic properties. In particular, the electronic charge distribution is analyzed by Mulliken, Hirshfeld-I, Bader and Wannier approaches. Calculations are performed at the PBE and the PBE0 level (for doping with Cu, only PBE0), with both spin-restricted and spin-unrestricted formulations; unrestricted calculations are used for spin-polarized cases and for the naturally open-shell cases (Cu doping).

α-AgZnWO (0 ≤ x ≤ 0.25) Solid Solutions: Structure, Morphology, and Optical Properties.

A theoretical study was elaborated to support the experimental results of the Zn-doped α-AgWO. Theses α-AgZnWO (0 ≤ x ≤ 0.25) solid solutions were obtained by coprecipitation method.

Computational study of Th(4+) and Np(4+) hydration and hydrolysis of Th(4+) from first principles.

The aqueous solvation of Th and Np in the IV oxidation state was examined using cluster models generated by Monte Carlo simulations and density functional theory embedded within the COSMO continuum model to approximate the effect of bulk water. Our results suggest that the coordination number (CN) for both Th(IV) and NP(IV) should be 9, in accordance to some experimental and theoretical results from the literature. The structural values for average oxygen-metal distances are within 0.

Europium doped zinc sulfide: a correlation between experimental and theoretical calculations.

This paper presents the correlation among electronic and optical property effects induced by the addition of different concentrations of europium (Eu3+) in zinc sulfide (ZnS) by microwave-assisted solvothermal (MAS) method. A shift of the photoluminescence (PL) emission was observed with the increase of Eu3+. The periodic DFT calculations with the B3LYP hybrid functional were performed using the CRYSTAL computer code.

Theoretical insight into the mechanism for the inhibition of the cysteine protease cathepsin B by 1,2,4-thiadiazole derivatives.

Several cellular disorders have been related to the overexpression of the cysteine protease cathepsin B (CatB), such as rheumatic arthritis, muscular dystrophy, osteoporosis, Alzheimer's disease, and tumor metastasis. Therefore, inhibiting CatB may be a way to control unregulated cellular functions and prevent tissue malformations. The inhibitory action of 1,2,4-thiadiazole (TDZ) derivatives has been associated in the literature with their ability to form disulfide bridges with the catalytic cysteine of CatB.

Preparation of TiO2/SnO2 thin films by sol-gel method and periodic B3LYP simulations.

Titanium dioxide (TiO2) thin films are grown by the sol-gel dip-coating technique, in conjunction with SnO2 in the form of a heterostructure. It was found that the crystalline structure of the most internal layer (TiO2) depends on the thermal annealing temperature and the substrate type. Films deposited on glass substrate submitted to thermal annealing until 550 °C present anatase structure, whereas films deposited on quartz substrate transform to rutile structure at much higher temperatures, close to 1000 °C, unlike powder samples where the phase transition takes place at about 780 °C.

Photocatalytic activity of semiconductor sulfide heterostructures.

This paper reports a theoretical and experimental study of the heterostructure photocatalytic activity in a CdS or ZnS and CdS@ZnS decorated system prepared by a microwave assisted solvothermal (MAS) method. A theoretical model of the decorated system was created in order to analyze the electronic transition mainly in their interface. The results show that CdS and ZnS interfaces produce an electron charge transfer from the CdS electron-populated clusters to the ZnS hole-populated clusters which helps to enhance the photocatalytic activity of the CdS@ZnS decorated system.

DFT study with inclusion of the Grimme potential on anatase TiO2: structure, electronic, and vibrational analyses.

Periodic DFT/B3LYP calculations for TiO(2) anatase bulk were carried out including semiempirical dispersive interactions (DFT-D2) to pure Khon-Sham DFT energy. From this standard methodology, van der Waals (vdW) radii were optimized to 1.4214 Å for titanium and 1.

Joint experimental and theoretical analysis of order-disorder effects in cubic BaZrO3 assembled nanoparticles under decaoctahedral shape.

Periodic first-principles calculations based on density functional theory at the B3LYP level has been carried out to investigate the photoluminescence (PL) emission of BaZrO(3) assembled nanoparticles at room temperature. The defect created in the nanocrystals and their resultant electronic features lead to a diversification of electronic recombination within the BaZrO(3) band gap. Its optical phenomena are discussed in the light of photoluminescence emission at the green-yellow region around 570 nm.