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Due to the water-insoluble nature of Hg0, its oxidization to Hg2+, which is water-soluble, is a viable approach for its effective removal at coal-fired plants using existing flue gas desulfurization (FGD) unit. In this study, the adsorption and oxidation of elemental mercury on an Mn-doped g-C3N4 material were investigated. The spin-polarized density functional theory method was adapted to optimize the geometry structures and then to determine the corresponding electronic structures, while the CI-NEB method was adopted to search for the stable intermediates during the reaction(s). The analysis of energy and project density of states shows that the Mn-g-C3N4 exhibits an excellent affinity to Hg atoms. It is found that it is feasible for Hg atoms to oxidize on the Mn-g-C3N4 surface via two possible E-R paths, but with relatively high energy barriers. This research provides insights into a viable way for mercury removal using O2 as the oxidizing agent.

Calculations of AgSbTe2 thermoelectric material and 2d CdS/TiS2 and their heterostructures were carried out using Density Functional Theory in Cambridge Serial Total Energy Package code as implemented in Material Studio 2018 software. The work function, thermal transport, electronic and optical properties were calculated. The results revealed that the heterostructures are possible to be achieved with improved properties. The electronic and thermal transport properties were likened with the description of equations derived from Boltzmann transport theory and Mott expressed in the maximum achievable Figure merit. Orbital contributions from the electron movement show valence and conduction band atomic shells.

Density functional theory (DFT) calculations have been performed to investigate the hydrogen dissociation and diffusion on Mg (0001) surface with Ni incorporating at various locations. The results show that Ni atom is preferentially located inside Mg matrix rather than in/over the topmost surface. Further calculations reveal that Ni atom locating in/over the topmost Mg (0001) surface exhibits excellent catalytic effect on hydrogen dissociation with an energy barrier of less than 0.05 eV. In these cases, the rate-limiting step has been converted from hydrogen dissociation to surface diffusion. In contrast, Ni doping inside Mg bulk not only does little help to hydrogen dissociation but also exhibits detrimental effect on hydrogen diffusion. Therefore, it is crucial to stabilize the Ni atom on the surface or in the topmost layer of Mg (0001) surface to maintain its catalytic effect. For all the case of Ni-incorporated Mg (0001) surfaces, the hydrogen atom prefers firstly immigrate along the surface and then penetrate into the bulk. It is expected that the theoretical findings in the present study could offer fundamental guidance to future designing on efficient Mg-based hydrogen storage materials.

The Dzyaloshinskii-Moriya interaction (DMI) manifesting in asymmetric layered ferromagnetic films gives rise to non-colinear spin structures stabilizing magnetization configurations with nontrivial topology. In this work magnetization reversal, magnetic domain alignment, and strength of DMI are related to the crystalline structure of W/Co/Pt multilayers grown by molecular beam epitaxy. The applied growth method enables the fabrication of layered systems with higher crystalline quality than commonly applied sputtering techniques. A relatively high value of the D coefficient was determined from the aligned magnetic domain stripe structure, substantially exceeding 2 mJ m-2. The highest value of DMI strength Deff = 2.64 mJ m-2 and surface DMI parameter DS = 1.83 pJ m-1 have been observed for a repetition number equal to 10. The experimental results correlate exactly with those obtained from the micromagnetic modelling and density functional theory calculations performed for the well-defined layered stacks. This high value of DMI strength originates from the additive contributions of the interfacial atomic Co layers at the two types of interfaces.

Lead-based relaxor ferroelectrics are key functional materials indispensable for the production of multilayer ceramic capacitors and piezoelectric transducers. Currently there are strong efforts to develop novel environmentally benign lead-free relaxor materials. The structural origins of the relaxor state and the role of composition modifications in these lead-free materials are still not well understood. In the present contribution, the solid-solution (100-x)(Bi1/2Na1/2)TiO3-xBaTiO3 (BNT-xBT), a prototypic lead-free relaxor is studied by the combination of solid-state nuclear magnetic resonance (NMR) spectroscopy, dielectric measurements and ab-initio density functional theory (DFT). For the first time it is shown that the peculiar composition dependence of the EFG distribution width (ΔQISwidth) correlates strongly to the dispersion in dielectric permittivity, a fingerprint of the relaxor state. Significant disorder is found in the local structure of BNT-xBT, as indicated by the analysis of the electric field gradient (EFG) in 23Na 3QMAS NMR spectra. Aided by DFT calculations, this disorder is attributed to a continuous unimodal distribution of octahedral tilting. These results contrast strongly to the previously proposed coexistence of two octahedral tilt systems in BNT-xBT. Based on these results, we propose that considerable octahedral tilt disorder may be a general feature of these oxides and essential for their relaxor properties.

Amino acid family crystals play vital role in the field of nonlinear optics (NLO) due to needs of wide range of applications in the current era. In this report, NLO crystals (L-Isoleucine D-Norvaline (LIDNV) are grown by slow evaporation method at room temperature and various properties of the material are studied and reported. The functional groups present in the grown crystal were identified by the FT-IR spectral analysis. In this work, the hyperpolarizability is investigated using density functional theory. The thermal analysis studies indicate that the material possess optimum thermal stability. Kurtz Perry powder technique using pulsed Nd:YAG laser is employed to confirm the SHG potential of the grown crystal.

The structure of 3-Bromo Phenyl Acetic acid (3BPAA) is optimized and its special features are probed by the FTIR, FT-Raman, UV-Visible and NMR with density functional theory calculations by B3LYP level with 6-311++G(d,p) basis set. The electronic properties were discussed with help of UV-Vis spectrum, MEP (Molecular electrostatic potential) and HOMO-LUMO (Highest occupied molecular orbital and Lowest unoccupied molecular orbital) plots. The energy band gap is found as 4.4437eV. The chemical shift is determined from proton and carbon NMR (Nuclear magnetic resonance) plot by Gauge Independent Atomic Orbital (GIAO) method. The surface analysis such as ELF (Electron localization function), LOL (Localized orbital locator) and ESP (Electrostatic potential) maps are plotted by wave function analyzer. Thermodynamic functions are studied and correlated with the graph. FMO and Fukui functions were calculated and found that the title compound is a chemically soft material. The NLO behavior of the compound is also examined and reported to have higher hyperpolarizability value greater than urea, the reference material ensuring good non-linear optical (NLO) activity. The molecular docking is performed by AUTODOCK tool, its study reveals that the title compound binds well with the protein L- glucorante reductose inhibition. Thus the present work study reports the structural, chemical, electronic, thermodynamic and biological activities of 3BPAA.

Electronic structure calculation explores the molecular structure and geometric conformations of the molecules from only the knowledge of its constituent atoms. In the present work, quantum mechanical calculations of a 3-phenyl-1-(methyl-sulfonyl)-1H-pyrazolo[3,4-d]pyrimidine-4-amine molecule have been performed by Density Functional Theory using the standard 6-31G** basis set with the GAUSSIAN09. The electronic structure, dipole moment, frontier orbitals energy, thermal parameters (entropy, enthalpy, internal energy, and Gibb’s potential), Infrared (IR) spectral lines of the title molecule are elaborated. To study the chemical reactivity; molecular electrostatic potential (MEP) surface, HOMO-LUMO surface, and some other properties of the molecule were also investigated.

Density functional theory (DFT) has become a powerful tool in the investigation of the molecular structure and vibrational spectrum of the compound. Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of the title compound were recorded experimental and theoretical study has been done by quantum computational calculations of DFT using Gaussian software package. The structural, vibrational and electronic properties of the title compound were presented using the B3LYP method with 6-311++G(d,p) basis set. The geometry of the title compound was optimized. The experimental vibrational spectra were compared with the calculated spectra and each wave number was assigned on the basis of potential energy distribution (PED). Molecular electrostatic potential for the title compound was calculated to predict the reactive sites for electrophilic and nucleophilic attack. Energy band gap of 3.62 eV was calculated from HOMO-LUMO energies and the charge transfer within the molecules was confirmed. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been calculated and the title compound exhibits NLO property. The biological activity has been confirmed theoretically for the treatment of lung cancer.

In this paper, the optimization of the structure of di(hydroxybenzyl) diselenide and its studies on HOMO and LUMO energy levels, hardness and Mulliken population using density functional theory (DFT)are reported. Molecular optimization is carried out at all the eight GGA functionals. The total minimum energy is calculated for the titled molecule at various functionals are in the order of BLYP > RPBE > BOP > PBE > PW91 > VWN-BP > BP > HCTH. Therefore, the results obtained at BLYP functional are considered for the remaining study of this work. From the contribution of the bands, the calculated HOMO-LUMO electronic transition is 2.101 eV. The study of HOMO and LUMO is extended to the calculation of the electron affinity, the ionization potential, and the chemical hardness. Chemical shifts for 1H and 13C NMR are also predicted. In 1H and 13C NMR, H25/ H32 and C5/C16 resonance signals are expected to be highly deshielded based on the Mulliken population analysis.

Semiorganic single crystals of L-Threonine Lithium Chloride were wealthy developed by slow evaporation method at ambient circumstances. The structure was illuminated by single crystal XRD technique and the structure be owned by orthorhombic system. Density functional theory computations using B3LYP/6-311++ G(d,p) base set gives optimized structural parameters of title compound. The Theoretically identified hyperconjugative molecular interactions are accountable for the stabilization of compound are obtain by NBO analysis. Besides, Mulliken atomic charges and molecular electrostatic potential were also executed.

Theoretical and experimental investigations on the molecular structure of 2-amino-5-chloro-3-nitropyridine (2A5Cl3NP) are presented. The molecular equilibrium geometry of the title molecule is fully optimized. Quantum chemical calculations of the HOMO-LUMO energies, energy gap (ΔE), electron negativity (χ), and chemical potential (μ), global hardness (ƞ), and global softness (S) are calculated for the title molecule. The title compound has a low softness value (0.2770) and the calculated value of electrophilicity index (7.7250) describes the biological activity. The stability and charge delocalization of the title molecule are studied by Natural Bond Orbital Analysis (NBO), Non-Linear Optical (NLO) behaviour in terms of first order hyperpolarizability, dipole moment, anisotropy of polarizability are accounted. The computed values of dipole moment (μ) for 2A5Cl3NP molecule is 3.0173 Debye, polarizability (α) is 1.6017 × 10–23esu, hyperpolarizability (β) is 5.08173 × 10–30esu. The high β value and non-zero value of μ indicate that the title compound might be a good candidate for NLO material. The strength of the interaction between electron donors and electron acceptors is measured by the magnitude of energy of hyper conjugative interactions E (2). The second-order Fock matrix is calculated to study the donor–acceptor interactions in NBO analysis.

Single crystals of L-Argininium Hydrogen Squarate (LAHSQ) were obtained from slow evaporation solution growth method using deionised water (1:1) as a solvent. The molecular structure and vibrational spectrum of LAHSQ single crystal has been investigated by Density Functional Theory (DFT) method. Single crystal X-ray Diffraction (SXRD) analysis has been used to identify the structure, cell-parameters and space group of the LAHSQ grown singe crystal. It revealed that the present crystal structure is triclinic system with P1 space group. The molecular structure was analysed by identifying the functional groups from FT-IR spectra were calculated and the results are compared to the experimental data, exhibited a good overall agreement. HOMO-LUMO energy gap was found to be 3.1789 eV. The Kurtz-Perry powder technique has been used to found the Second Harmonic Generation (SHG) of LAHSQ crystal. Theory (DFT) calculations have been worked under solvation model to know the geometrical and electronic structural characters like frontier molecular orbital analysis (FMO), Mulliken population analysis, dipole moment, polarizability, and hyperpolarizability of the crystal. All these results agree that the LAHSQ crystal is appropriate for NLO applications.

This study describes structural, electronic and mechanical properties of SnTe and SnTe0.5Se0.5 compound by using the spin-polarized full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). The structural parameters, density of states and band structure have been analyzed using the generalized gradient approximation (GGA). The calculated density of states (DOS) of these compounds is discussed in terms of contribution from various s, p and d-states of the constituent atoms. The computed elastic constants indicate that SnTe and SnTe0.5Se0.5 are mechanically stable. Also, Bulk modulus, Shear modulus, Young’s modulus, Poison’s ratio and Hardness were investigated.

This paper describes the spectroscopic (FT-IR and UV–Visible), electronic, structural, vibrational properties of celecoxib compound using density functional theory. The optimized geometry structure of the titled molecule is explained by the method of B3LYP with 6–31 + G (d, p) basis set. We found that the simulated optimized geometry of the titled molecule is simulated to the experimental ones. The infrared spectrum of celecoxib compound is represented in the present work. The computational information about the organic molecule can be explained by the charge transfer properties, which is a computational tool for the precise quantum chemical calculations of space charge density distribution and HOMO-LUMO states. The transition states of celecoxib compound have explained by the time-dependent density functional theory (TD-DFT) which is observed by the UV–visible spectrum. Docking research [1] is a modeling method, with the help of docking method we can find out new drug and chemical behavior of the drug which is useful in the application purpose of the drug, the interaction between protein and legends provides the information of the binding energy and physical parameter like partition function, free energy, internal energy, entropy.

The compound of L-Glycinium 5-Nitrouracilate were grown by slow solvent evaporation technique at room temperature method. Structural investigation by single crystal XRD reveals that LGY5N crystallizes in monoclinic system with space group P21/c. Vibrational spectroscopic studies were performed by utilizing FT–IR spectral analysis along with DFT/B3LYP/6-311++G(d,p) method using GAUSSIAN 06 software. The molecular structure of LGY5N crystal has also been optimised by using Density Functional Theory (DFT) using method with B3LYP/6-311++G (d, p) basis methods in order to find the whole characteristics of the molecular complex. The HOMO and LUMO energy results show that good exchange of charge happened inside the molecule. The electronic absorption spectrum of organic molecules that shows alteration due to the solvation processes was evaluated by TD-DFT in the gas and solvent phase in addition to the recorded UV–visible spectrum. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystal.

(1S)-(+)-10-Camphorsulfonic Acid has a promising application in medical field as an anti-inflammatory drug. According to the present studies, the structural and spectral characteristics, and the reactivity of the title compound were carried out using Density Functional Theory (DFT), with B3LYP/6–311++G(d,p) as the basis set. Experimental techniques such as FT-IR, FT-Raman were in good agreement with the theoretical results. The intermolecular and intramolecular interactions of the title compound are interpreted from the NBO analysis. Molecular Electrostatic Potential (MEP), Frontier Molecular Orbitals (FMO), The intermolecular charge transfer within the molecule is confirmed from the charge transfer interactions, also among all the reagents Camphorsulfonic acid were found to be the best reagent. NLO and Thermodynamic Properties were also calculated. The molecular docking analysis were carried out to study the biological activity of the compound.

Organic nonlinear optical single crystal of L-Isoleucine D-Valine (LIDV) with dimensions 3 X 3 X 4 mm3 was successfully grown by the slow evaporation solution growth technique (SEST). The structural analysis of the grown crystals has been analyzed by Powder X-ray diffraction which revealed that grown (LIDV) crystal belongs to monoclinic crystal system with P21 space group. The structure of LIDV is optimized using Density Functional Theory (DFT) method. The vibrational band assignments were performed at B3LYP/6-31G + (d, p) theory level. The theoretical IR frequencies are found to be in good agreement with the experimental IR frequencies. Nonlinear optical (NLO) behavior of LIDV is examined by the theoretically predicted values of first hyper polarizability. The cut-off wavelength and the optical band gap value of the grown crystal is found using Optical studies. The SHG efficiency of the grown material is found to be 2.5 times the reference material.

The present work investigates on structural and chemical studies on 1-Phenyl Sulfonyl Pyrrole(1PSP) using quantum computational methods. The revamped geometric structure and its parameters were obtained through density functional theory (DFT). The electronic absorption transitions were discussed with different solvents were carried out by TD-DFT (Time Dependent Density Functional Theory) method. The IR intensities and Raman activites are tabulated for vibrational wavenunbers and its corresponding PED (Potential Energy Distribution) assignments in percentage were obtained from VEDA4 software. The inter and intra molecular interactions, electrophilic, nucleophilic and chemical reactivity sites are identified by Molecular electrostatic Potential (MEP), HOMO-LUMO (Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital) and GCRD (Global chemical reactivity descriptors). Mulliken atomic charges were discussed with Natural Bond Orbital (NBO) analysis. Thermodynamic property and Non-linear optical deportment of the title compound is also talked about. Besides the electron localization function map, the density of states are also mapped with Multiwfn software, a wavefunction analyzer.

The variation in geometrical and electronic properties of armchair graphene nanoribbon (AGNR) along with pristine and phosphorus (P-AGNR) doped configuration in the presence of ammonia gas (NH3) have been identified in this work. The density functional theory based calculations have been performed in order to detect and equate the sensitivity of modified armchair graphene nanoribbon towards NH3 sensing. Further, the variation in geometrical and electronic properties of AGNR and P-AGNR have been analyzed by considering the cohesive energy, band structure, density of states, and conductance. Hence, our findings shows that P doped AGNR can upsurge its sensitivity towards NH3 gas by the order of 106 times owing to the enhancement in the conductance. Overall, results shows the great potential in the area of designing the graphene nanoribbon based sensors.

Density Function Theory is one of the most popular and recommended computational quantum Mechanical method used for the analysis of molecular structure and vibrational spectra. L-Isoleucine is one of the amino acid which is known to be a hydrophobic amino acid and it has zwitterion nature in solution. L-Maleic acids are also organic acid with large π-conjugation with which has attracted great deal of attention. A non-centrosymmetric Nonlinear Optical single crystal of L-Isoleucinium Hydrogen Maleate Hemihydrates (LIM) were grown from aqua solution by slow evaporation solution growth method. The Molecular structure of LIM single crystal were optimized using Density function theory (DFT) method B3LYP with 6-311++G(d,P) basis set. The molecular structure of LIM was then confirmed by SXRD and the crystal exhibited Monoclinic structure with the space group P21. FTIR, FT-RAMAN and Potential energy distribution of LIM molecules were calculated and compared with experimental values. Band gap energy of LIM crystal was calculated by HOMO-LUMO energies and it is found to be 5.621 eV which confirm the inter molecular charge transfer within the molecule. In the present work, Natural bond Orbital analysis (NBO), Fukui Functions calculations Molecular Electrostatic Potential (MEP), First Order Hyperpolarizability were discussed.

The protein adsorption has an immense influence on the biocompatibility of biodegradable Mg alloy. In this work, the effect of Zn content on the fibrinogen (Fg) adsorption behavior in Mg-Zn binary alloy was systematically investigated. Experimental results showed that the Fg adsorption amount increased at first and then decreased with the increase of Zn content. The adsorption mechanism was investigated by molecular dynamic and density functional theory simulations. The simulations results showed that Zn with low content existed in the inner layer of Mg alloys due to the lower system energy, which promoted Fg adsorption and the promotion effect was more obvious with the increase of Zn content. When Zn content increased to a higher concentration, parts of Zn atoms started to precipitate in the surface, and the Fg-surface interaction energy started to increase. Moreover, the Zn sites favored the formation of ordered water molecules layers, which inhibit the stable adsorptions of Fg. The inhibition effects of Fg adsorption was enhanced with the Zn content increase. In short, the simulation results explain the experimental phenomena and reveal the microscopic mechanism. This study would provide a significant guidance on the design of biodegradable Mg-Zn alloys.

We present vibrational properties of Franckeite, which is a naturally occurring van der Waals heterostructure consisting of two different semiconducting layers. Franckeite is a complex layered crystal composed of alternating SnS$_2$ like pseudohexagonal and PbS-like pseudotetragonal layers stacked on top of each other, providing a unique platform to study vibrational properties and thermal transport across layers with mass density and phonon mismatches. By using micro-Raman spectroscopy and first-principles Raman simulations, we found that the PbS-like pseudotetragonal structure is mostly composed of Pb$_3$SbS$_4$. We also discovered several low-frequency Raman modes that originate from the intralayer vibrations of the pseudotetragonal layer. Using density functional theory, we determined all vibrational patterns of Franckeite, whose signatures are observed in the Raman spectrum. By studying temperature dependent Raman spectroscopy (300 K - 500 K), we have found different temperature coefficients for both pseudotetragonal and pseudohexagonal layers. We believe that our study will help understand the vibration modes of its complex heterostructure and the thermal properties at the nanoscale., Comment: 15 pages, 10 figures

In this work, we report on the structural, electronic, and ferroelectric properties of SmMn2O5 by using first-principles density functional theory plus on-site Coulomb interaction (DFT + U) calculations. A thorough analysis was preformed to reveal the competing characteristics of different high-temperature (T) phases and the polarization mechanism in the low-T multiferroic phase. We show that the structural characteristics of the high-T phases have a strong influence on the low-T multiferroicity. In addition to the spin-induced lattice distortion that reduces substantially the purely electronic ferroelectricity, the dominant polarization mechanism in low-T SmMn2O5 still originates from the electronic polarization. By performing mode decomposition of the Hellmann–Feynman forces and the lattice distortion induced by the q = (0.5, 0, 0) magnetic order, we find that the Raman-active Ag mode characterized by the Mn4+O6 octahedron distortion and synergistic displacement of Mn3+ and Sm ions is of primary importance, while the infrared (IR)-active B2u mode plays a secondary role. These findings provide a theoretical foundation for future studies concerning the enhanced magnetoelectric effects of SmMn2O5 due to its pure exchange–striction mechanism.

Silicon carbide surface modification is still a challenging task. Its modification mechanism is also still unclear. This paper provides a study of the surface modification mechanism of KH5X0 (X = 5, 6, 7, 8, 9) on the silicon carbide (111) using density functional theory. The electronic structures and densities of states of KH5X0 (X = 5, 6, 7, 8, 9) on SiC surfaces indicates that the surface modification mechanism is attributed to the electronic effects of the functional groups of KH5X0 (X = 5, 6, 7, 8, 9). From the results the easier it is for a functional group to obtain electrons, the better the modifying performance of silane coupling agent will be. Furthermore, the interface energy results showed that silicon carbide (111) modification performance by KH580 silane and KH590 silane is better than KH550, KH560, and KH570. The present work provides theoretical guidance for the fabrication of SiC heat sink products.

The Li4TiO4 ceramic is a promising solid-state tritium breeder material for the production of tritium fuel in the designs of fusion reactors. Tritium extraction efficiency is one of the key factors that determines the performance of the breeder material. Vacancies are known to trap tritium and adversely affect tritium extraction. Understandings of tritium-trapped defect configurations in Li4TiO4 are limited so far. In this work, the oxygen/lithium vacancy (VO/Li) and the vacancy-tritium defect complex (VO/Li + T) in Li4TiO4 are studied by first-principles density functional theory. The atomic configurations, formation energies and electronic structures of various charged defect species are obtained. We find that 2+ and 0 are the dominate charge states of VO, 1- is the dominate charge state of VLi, 1+ is the dominate charge state of the defect complex (VO + T), and 0 is the dominate charge state of (VLi + T). Tritium atoms trapped in VO are bonded to Ti atoms, and those trapped in VLi are bonded to O atoms.

The series of novel phosphors Ca9La(PO4)5 [(Si1-xGexO4)]F2:0.15Dy3+ with x = 0, 0.25, 0.50, 0.75 and 1 (CLPS1-xGxF:0.15Dy3+) with apatite-type structure (space group P63/m) has been synthesized. The crystal structure and electronic structure have been studied by powder X-ray diffraction (PXRD) in combination with the atomic-scale density functional theory (DFT) calculations. A combination of Raman, nuclear magnetic resonance (29Si NMR) spectroscopy and the evolution of Dy3+ ions photoluminescent properties was used to characterize the local crystal structure features. Based on the variation of the [SiO4] by [GeO4] tetrahedral substitutions in the apatite-type structure, the difference in the thermal stability and decay curves of CLPS1-xGxF:0.15Dy3+ phosphors were referred to crystal chemical stability of as-prepared compounds, which is also confirmed by the values of polyhedral distortion, bond valence sum (BVS) and DFT calculations. The present study provides new insights the synthetic methodology and fundamental characterizations into the design of new phosphors combined with theoretical methods.

We have evaluated the interactive nature of attapulgite (ATB) and PLA (Poly (lactic acid)) by dispersion corrected density functional theory (DFT‒D2) calculations and reactive molecular dynamic (MD) simulations. Our DFT‒D2 findings revealed that PLA interacted strongly with pristine and calcined ATB surface with interaction energies of -4.706 and -10.101 eV, respectively. The accuracy of obtained interaction energies has been validated against the advanced second order Moller–Plesset level. Atom‒in‒molecule (AIM) analysis illustrated that the interactive nature was typical for the chemisorption (high polar and partially covalent) in PLA/calcined ATB and strong physisorption (hydrogen bonding) in PLA/pristine ATB system. Finally, reactive MD simulations at room temperature showed that as result of strong attraction between PLA and ATB surface a clear approaching and bonding procedure between O atom from PLA and H/Al atom of ATB was observed in pristine/calcined crystal.

In this study, we undertake a Bayesian optimization of the Hubbard U parameters of wurtzite GaN and InN. The optimized Us are then tested within the Hubbard-corrected local density approximation (LDA+U) approach against standard density functional theory, as well as a hybrid functional (HSE06). We present the electronic band structures of wurtzite GaN, InN, and (1:1) InGaN superlattice. In addition, we demonstrate the outstanding performance of the new parametrization, when computing the internal electric-fields in a series of [InN]1–[GaN]n superlattices (n = 2–5) stacked up along the c-axis.

Until now, many attempts have been made to dope graphene in various ways, but each method turned out to have pros and cons. In this study, to overcome the limitations of doping methods, yttrium hypocarbide (Y2C) is investigated as one prospective material to dope graphene, using density functional theory calculations. In monolayer Y2C, the anionic electrons localized away from Y atomic layers are confirmed to contribute to occupied states near the Fermi level. Next, we investigate the electronic structure of graphene in heterojunction with Y2C. Anionic electrons of Y2C occupy the empty states of graphene in graphene/Y2C heterostructure, which makes the Dirac cone of graphene located at about 1.7 eV below the Fermi level. Such charge transfer of anionic electrons to graphene and the flatness of electric cloud of anionic electrons leads to evenly n-doped graphene in graphene/Y2C heterostructure. This suggests that Y2C is a good candidate to dope graphene.

Understanding the quantum dynamics of spin defects and their coherence properties requires an accurate modeling of spin-spin interaction in solids and molecules, for example by using spin Hamiltonians with parameters obtained from first principles calculations. We present a real-space approach based on density functional theory for the calculation of spin-Hamiltonian parameters, where only selected atoms are treated at the all-electron level, while the rest of the system is described with the pseudopotential approximation. Our approach permits calculations for systems containing more than 1000 atoms, as demonstrated for defects in diamond and silicon carbide. We show that only a small number of atoms surrounding the defect needs to be treated at the all-electron level, in order to obtain an overall all-electron accuracy for hyperfine and zero-field splitting tensors. We also present results for coherence times, computed with the cluster correlation expansion method, highlighting the importance of accurate spin-Hamiltonian parameters for quantitative predictions of spin dynamics.

Li4SiO4 crystal is a candidate material for tritium breeder material. Vacancy defects and He atoms will be produced in the crystal after neutron irradiation in fusion reactor. In previous research, we learned vacancy defects mainly include VO0, VO2+, and VLi0, meanwhile, He atoms are easy to migrate and aggregate in the crystal. In order to understand the relationship between vacancy defects and He atoms, we use density functional theory (DFT) to study the interaction mechanism between vacancy and He atom. The results show that the local stable sites of He atoms are related to the surrounding charge distribution. VO2+ and VLi0 can capture interstitial He atoms, and it is difficult to escape the vacancies, thereby increasing the nucleation center of He atoms. VO0 promotes the diffusion of He atoms in the interstitial space, which will cause small helium bubbles to merge more easily.

Single-phase multiferroic materials that allow the coexistence of ferroelectric and magnetic ordering above room temperature are highly desirable, motivating an ongoing search for mechanisms for unconventional ferroelectricity in magnetic oxides. Here, we report an antisite defect mechanism for room temperature ferroelectricity in epitaxial thin films of yttrium orthoferrite, YFeO3, a perovskite-structured canted antiferromagnet. A combination of piezoresponse force microscopy, atomically resolved elemental mapping with aberration corrected scanning transmission electron microscopy and density functional theory calculations reveals that the presence of YFe antisite defects facilitates a non-centrosymmetric distortion promoting ferroelectricity. This mechanism is predicted to work analogously for other rare earth orthoferrites, with a dependence of the polarization on the radius of the rare earth cation. Our work uncovers the distinctive role of antisite defects in providing a mechanism for ferroelectricity in a range of magnetic orthoferrites and further augments the functionality of this family of complex oxides for multiferroic applications., Ferroelectricity in orthoferrite perovskites has stimulated intense research, but the mechanism remains unclear. Here, the authors propose an antisite defect mechanism for introducing ferroelectricity in magnetically ordered YFeO3 and the family of rare earth orthoferrites.

The density of states and quantum capacitance of pure and doped niobium nitrides are investigated using density functional theory calculations. Out of pristine structures investigated, NbN is the most promising candidate for fabrication of supercapacitor electrodes with quantum capacitance values reaching up to 834.5 and 1683.7 Fg-1 at negative and positive electrodes respectively. These calculations are also performed for cobalt doped niobium nitrides. The results suggest that doping of niobium nitrides with cobalt can further increase the quantum capacitance significantly. Quantum capacitance of both pristine and doped niobium nitrides is found to be much higher than that of graphene near fermi level, thus suggesting that these structures can be preferred over graphene for supercapacitor electrodes. The temperature dependence of quantum capacitance is also investigated.

Li2MoO3 (LMO) is a promising stabilization block for constructing high performance lithium-rich layered oxides. However, its poor electronic conductivity, surface instability in air, and capacity degradation are drawbacks for the application. To solve these issues, non-equivalent Nb5+ dopants were introduced into the LMO lattice. Density functional theory (DFT) calculations combined with experimental characterizations have confirmed that Nb5+ doping not only enhances the Mo–O bonds of LMO but also reduces its band gap and further suppresses the oxidation of surface Mo4+, leading to a much-improved lattice and surface stabilities. Therefore, the electrochemical performances of LMNO are improved obviously. The initial discharge capacities of LMO, LMNO-0.01, LMNO-0.02, and LMNO-0.03 are 232.6, 234.7, 251.6, and 246.3 mAh·g−1, respectively. LMNO-0.02 exhibits the best performance, and its specific capacities at the 1st and 100th cycles reach 144.13 and 72.06 mA g−1 under a 3C charging rate and a 5C discharging rate. Our results have demonstrated that non-equivalent cationic doping is an effective strategy to modulate the bonding characteristics of LMO and therefore to improve its electrochemical performance.

Owing to the large surface area, high thermal stability and good conductivity, few polymers have emerged as potential candidate for the trace level detection of anticancer drugs. The present work explores the electronic properties and stability of aniline, 9 vinyl carbazole, and their copolymer (Ani-NVK), studied employing density functional theory (DFT) based approach. Analysis of stability and electronic characteristics of aniline-9 vinyl carbazole copolymer in comparison to the monomers show reduced HOMO-LUMO gap, variation in density of state (DOS) and decrease in total energy. It is observed that copolymerization enhances the designing capability of electrochemical polymeric sensor for detection, quantification, validation and determination of anti-cancer drugs in comparison to the sensors based on Aniline and 9 vinyl carbazole.

The paper reports a study, on calculations performed through plane wave Density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) formalism, to analyze the electronic and structural properties of armchair graphene nanoribbons (AGNR) doped with Phosphorous (P) (N type), and Gallium (Ga) (P type), with two different doping concentration viz 6.25% and 12.5%. It has been observed that (3, 0) Pristine AGNR exhibit a band gap of 1.06 eV. While, on doping with P, and Ga induce metallicity in AGNR, where with increasing doping concentration current increases linearly in Ga doped AGNR whereas, with increasing concentration of P, current decreases in P doped AGNR but AGNR remains Metallic. AGNRs with 6.25% doping concentration can be used as interconnect application due to linear rise in current and other counterparts can be used in electrode of transistor.

In present work, the polyvinyl alcohol-lithium-silicon nitride (PVA-Li-Si3N4) novel structures were designed to use in various renewable and electronics approaches. The structure, optical and electronic characteristics of PVA-Li-Si3N4 structures were studied. The Density functional theory (DFT) was used to study of the influence of Li-Si3N4 on characteristics of PVA structure. The structure and electronic characteristics of the PVA-Li-Si3N4 were studied in relations of the calculated energy, ionization potentials, HOMO-LUMO gap, and electron affinity. The PVA-Li-Si3N4 structures are optimized successfully with Gaussian 09 package. The final results showed the PVA-Li-Si3N4 structures can be used in different optic and optoelectronics applications.

Pseudoboehmite was obtained through neutralization of ammonium aluminum sulfate solution [NH4Al(SO4)2·12H2O] with ammonia water [NH3 (aq)]. The neutralization process resulted in flake-like overlapping flower-like structures at 80 °C and 85 °C. When the temperature of the NH4Al(SO4)2·12H2O solution was raised to 90 °C, nanoparticles, microspheres with a diameter of less than 50 nm, were obtained. The (131) plane was studied by HRTEM imaging (high resolution transmission electron microscopy). Density functional theory was used to study the interface properties of the pseudoboehmite, and the surface energy and attachment energy were calculated for the optimized crystal planes of interest. The results show that the relaxed (131) plane has the lowest surface energy (0.0474 J/m2), and thus is the most stable surface. Additionally, the (200) plane of the pseudoboehmite has the lowest absolute value of attachment energy (0.2106 eV/unit), consistent with having the strongest X-ray diffraction peak and indicating that it is the preferred orientation. The formation mechanism of flower-like and microspherical particles is discussed, with consideration for solution temperature effects on morphology and the predicted equilibrium morphology and growth morphology of pseudoboehmite.

Cu2GeSe3 is an eco-friendly material, but pristine Cu2GeSe3 has poor thermoelectric properties. Here, the effects of magnetic Ni ion with unpaired 3d electrons on the electrical and thermal transport properties of Cu2GeSe3 are reported. Density functional theory (DFT) calculations indicate that the unpaired Ni 3d states cause the hybridization of Ni 3d orbitals with Se 4p orbitals near the Fermi level, giving rise to an increase in density of states (DOS). Combined with the significantly increased carrier concentration, a power factor (S2σ) value of ∼8.0 μWcm−1 K−2 at 723 K is achieved in Cu2Ge0.8Ni0.2Se3 sample, seeming to be the highest compared with the other Cu2GeSe3 systems. Meanwhile, the substitution of Ni for Ge causes the obvious local distortions in Cu2GeSe3 lattice, which yields the large strain fluctuations to suppress the lattice thermal conductivity. Consequently, a peak ZT value of ∼0.38 at 723 K is obtained in Cu2Ge0.9Ni0.1Se3 sample.

Based on the CALPHAD method combined with density functional theory (DFT) calculations, we performed a thermodynamic reassessment of the binary Fe-Y system leading to good agreement with the available experimental measurements. The electronic, vibrational, and magnetic contributions to the specific heat and thus the Gibbs free energy were evaluated based on accurate DFT calculations for the Fe-Y intermetallic compounds. Moreover, a new model was applied to describe the Gibbs free energies of such intermetallic phases which leads to significant improvements over the conventional thermodynamic expressions. The resulting phase diagram and thermodynamic properties are in good consistency with the previous experimental data, paving the way to designing multicomponent magnetic functional materials.

Point defects in hexagonal boron nitride (hBN) have attracted growing attention as bright single-photon emitters. However, understanding of their atomic structure and radiative properties remains incomplete. Here we study the excited states and radiative lifetimes of over 20 native defects and carbon or oxygen impurities in hBN using ab initio density functional theory and GW plus Bethe-Salpeter equation calculations, generating a large data set of their emission energy, polarization and lifetime. We find a wide variability across quantum emitters, with exciton energies ranging from 0.3 to 4 eV and radiative lifetimes from ns to ms for different defect structures. Through a Bayesian statistical analysis, we identify various high-likelihood charge-neutral defect emitters, among which the native VNNB defect is predicted to possess emission energy and radiative lifetime in agreement with experiments. Our work advances the microscopic understanding of hBN single-photon emitters and introduces a computational framework to characterize and identify quantum emitters in 2D materials.

We present a method to obtain Hugoniot from model calculations based on density functional theory, and apply the method to aluminum Hugoniot. Technological advances have extended the experimental research of high energy density physics, and call for quantitative theoretical analysis. However, direct computation of Hugoniot from density functional theory is very difficult. We propose two step calculations of Hugoniot from density functional theory. The first step is molecular dynamics simulations with an ambient temperature for electrons. The second step is total energy calculations of a crystal with desired high temperatures for electrons and with the ambient temperature for electrons. We treated the semicore 2s and 2p electrons of aluminum as valence electrons only for the total energy calculations of the aluminum crystal. The aluminum Hugoniot from our model calculations is in excellent agreement with available experimental data and the previous density functional theory calculations in the literature.

Thermodynamic properties, electronic structures and spectroscopic properties of defects and Ce3+ in Y2O3 are studied by using the hybrid density functional theory associated with multi-reference configuration interaction ab-initio calculations. Thermodynamic transition energy levels of the easily generated oxygen vacancies in the host are analyzed according to HSE06-calculated formation energies, which may be conducive to interpretations of the persistent luminescence (PersL) of Y2O3-based phosphors. Besides, the locations of impurity states (caused by VO and Ce3+) in energy bands are obtained from derived density of states. Moreover, energies and oscillator strengths of 4f1 → 5d1−5 transitions of Ce3+ ions (at Y1 and Y2 sites) calculated from the CASSCF/CASPT2/RASSI−SO method agree reasonably well with experimental excitation spectra of Y2O3: Ce3+ phosphors, achieving the assignment of excitation spectra. The presented calculations can be applied to identify luminescent centers in Ce3+-doped phosphors and reveals possible native defects and their roles in the PersL of phosphors.

The formation of stacking faults and polytypes in $${\hbox {ZnSnN}_2}$$ , $${\hbox {ZnGeN}_2}$$ , and $${\hbox {ZnSiN}_2}$$ was investigated by the first-principles density functional theory calculations. To analyze the interactions between the layers of polytypes, we constructed an anisotropic next-nearest neighbor interaction model that reproduced the DFT fitted total energies. Our calculation showed that the stacking fault energy is around 0.28 eV/nm $$^2$$ , indicating that the planar defect is expected to be formed in $${\hbox {ZnSnN}_2}$$ . The formation of stacking faults can be suppressed by replacing Sn with Si. Stacking faults produce a sawtooth-like potential due to polarization charge, resulting in the separation of electron and hole carriers.

The identification of the incorporated site of magnesium (Mg) and hydrogen (H) required for p-type formation in gallium nitride (GaN) power devices has been demonstrated by X-ray absorption spectroscopy (XAS). In this study, the fluorescence line of Mg with 3 × 1019 atoms cm−3 was successfully separated from that of Ga using a superconducting tunnel junction array detector with high sensitivity and high energy resolution, and consequently the Mg K-edge XAS spectra of such dilute samples were obtained. The site of Mg atoms incorporated into the GaN lattice was identified as the Ga substitutional site by comparing the experimental XAS spectrum with the simulated spectra calculated by density functional theory. In addition, the presence or absence of H around Mg can be determined through distinctive characteristics expected from the spectrum simulations.

International materials reviews (2021). doi:10.1080/09506608.2021.1930734, Published by Taylor & Francis, London

An ab initio study using density functional theory (DFT) is carried out to explore the structural, electronic, and optical properties of vanadium gallate (VGaO3) and niobium gallate (NbGaO3). The structural properties of these compounds are determined by using the full-potential linearized augmented plane wave (FP-LAPW) technique as implemented in WIEN2k with a standard functional, i.e., the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA). In addition, the local density approximation plus Hubbard parameter (LDA + U) is employed to calculate the electronic bandgap and total and partial density of states (TDOS and PDOS), to overcome the limitation of the PBE-GGA functional in terms of underestimation of the electronic bandgap. The values computed for the indirect bandgap of VGaO3 and NbGaO3 are 0.45 and 0.51 eV, respectively, indicating that both materials are semiconductors in nature. The PDOS of the studied materials reveal that 3d-states of vanadium atoms, 4d-states of niobium atoms, and 2p-states of oxygen atoms form the valence band. Moreover, the Kramer–Kronig relations are used to compute the optical properties of the title compounds. The dielectric functions, refractive index, optical conductivity, absorption coefficient, extinction coefficient, energy loss function, and reflectivity of these materials are also computed. The results for the studied properties reveal that NbGaO3 exhibits better properties than VGaO3 for use in optoelectronic applications.

Computer simulations of alloys’ properties often require calculations in a large space of configurations in a supercell of the crystal structure. A common approach is to map density functional theory results into a simplified interaction model using so-called cluster expansions, which are linear on the cluster correlation functions. Alternative descriptors have not been suf-ficiently explored so far. We show here that a simple descriptor based on the Coulomb matrix eigenspectrum clearly outper-forms the cluster expansion both for total energy and bandgap energy predictions in the configurational space of a MgO-ZnO solid solution, a prototypical oxide alloy for bandgap engineering. Bandgap predictions can be further improved by introducing non-linearity via gradient-boosted decision trees or neural networks based on the Coulomb matrix descriptor.

Zigzag and armchair graphene nanoribbons (ZGNR and AGNR) have been investigated using the density functional theory (DFT) and nonequilibrium Green’s function (NEGF) framework. Based on binding energy calculations, both-edge-F-functionalized ZGNR emerges as the most thermostatically and energetically stable among various ZGNR and AGNR configurations. The band structures and density of states (DOS) reveal that all the examined configurations of ZGNR exhibit metallic behavior. The I–V characteristics of both-edge-F-functionalized ZGNR shows pure linear behavior among all the configurations of ZGNR and AGNR. For interconnect modeling, the small-signal dynamic performance parameters RBq, CBq, and Lkq are calculated using the standard two-probe model. Furthermore, both-edge-F-functionalized ZGNR shows lower values of CBq (98.07pF/cm), Lkq (45.38nH/ $$\mu $$ m) and quantum delay (42.17 $$\mu $$ s) due to the higher Fermi velocity. The impact of variation of the contact length and ribbon length on the both-edge-F-functionalized ZGNR interconnect model is also presented. F-functionalized ZGNR is a potential candidate for use in future low-power nanoscale high-speed interconnect applications.