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Cubic halide based perovskite gained the attention of the researchers due to their remarkable optoelectronic contributions. The present work deals with the first principles calculations based on Density Functional Theory for exploring the TlSnX 3 (X = Cl , Br , I) cubic perovskites. The important physical characteristics are computed within Wien2k using Full Potential Linearized Augmented Plane wave, FP-LAPW method. The structural stability is examined by energy volume optimization. The optimized lattice constant of TlSnCl 3 , TlSnBr 3 and TlSnI 3 is 5.58 Å, 5.83 Å and 6.20 Å. The electronic and optical properties are calculated using Generalized Gradient Approximation with Perdew–Burke–Ernzerhof, PBE-GGA, Trans-Blaha modified Becke–Johnson, TB-mBJ and Strongly Constrained and Appropriately Normed, SCAN exchange and correlation functionals. The studied compounds possess direct band gap nature with the band gap of 1.61 eV, 1.08 eV and 0.75 eV with TB-mBJ for TlSnCl 3 , TlSnBr 3 and TlSnI 3 . The band gap using PBE-GGA(SCAN) potentials for TlSnCl 3 , TlSnBr 3 and TlSnI 3 is 0.98 (0.78) eV, 0.67 (0.69) eV and 0.50 (0.48) eV, respectively. The mechanical analysis reveal that these compounds are ductile. The optical characteristics like ε (ω) , n (ω) , α (ω) , R (ω) , σ (ω) and L(ω ) are calculated by implementing PBE-GGA, TB-mBJ and SCAN XC. High absorption and low reflectivity make these perovskites potential candidates for sustainable energy applications. [ABSTRACT FROM AUTHOR]

In this work, the structural, electronic, elastic, optical, and magnetic properties for the B1, B2, and B3 phases of Sr0.875Mn0.125O with relaxed structure (RS) and unrelaxed structure (URS) are investigated. The investigations are accomplished by the adoption of first‐principle methods established on spin‐polarized density functional theory, based on the full‐potential linearized augmented plane wave method as implemented in the WIEN2k code, where the electronic exchange‐correlation potential is studied by the Perdew–Burke–Ernzerhof generalized gradient approximation (GGA‐PBEsol) and the revised TB‐mBJ rapprochement. The negative formation energy and elastic constant that are acquired indicate the thermodynamical and mechanical stability of all these structures. The ternary Sr0.875Mn0.125O alloys for all structures show half‐metallic ferromagnetic behavior with a spin polarization of 100 % at the Fermi level, except the B2 phase without unrelaxed structure (URS). The total magnetic moments are 5 µB for all compounds and the interaction is ferromagnetic between Mn─Sr and Mn─O sites. Optical properties such as refractive index and the optical reflectivity for these alloys are computed and discussed. These materials are half‐metallic ferromagnets, and they can be desirable applicants for spintronics implementations and ultraviolet spectra. [ABSTRACT FROM AUTHOR]

Density functional theory is applied to account the ligand effect on modification in the redox potential of coordination of three NN bidentate ligands (bpy/phen) to the metal ion (Fe2+/3+/Co2+/3+). Also, the role of the ligand framework for the stabilization of [M(bpy/phen)3]2+/3+ species is discussed in detail. In this work, we have found that the M2+ ions are more stabilized with the bpy ligands while the M3+ ions are more stable with the phen ligands. The electronic structure and geometrical study disclosed the electronic configurations of the metal ions in both the possible spin states of a species. Furthermore, the HOMO–LUMO analysis demonstrates that the M3+ ion coordinated species have more energy gap as compared to the M2+ ion coordinated species. Among all the species, HOMO–LUMO energy gap has been found highest (4.62 eV) in the [Fe(bpy)3]3+ whereas lowest (3.28 eV) in the [Co(phen)3]2+ species. Additionally, we have also found that the bpy coordinated species have relatively higher redox potential value as compared to phen ligated species. Here we have noticed a close relationship between the redox potential and the optimized structural parameters of the studied species. Also, all the computed structural parameters of the studied species are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

A recent study proved that β-ZrNBr displays multifunctionalities in optical applications. Based on DFT, a detailed investigation of crystal structures, electronic, and optical properties were investigated across monolayer, bilayer, trilayer, and bulk forms. Results revealed bulk and 2D ZrNBr are semiconductor nature with indirect band gaps decreasing with layer number. Electronic structure analysis highlighted contributions from Zr-4d, N-2p, and Br-4p hybrids. Optical properties including dielectric function, reflectance, absorption coefficient, and transmittance are also analyzed. The obtained results indicate that 2D and bulk ZrNBr are both p-type transparent conductive materials, with monolayer ZrNBr exhibiting superior performance in transparency and conductivity. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations, we have investigated the effects of different charged states of La K on the defect formation energies (DFE), lattice distortions, electronic structures, and optical properties of paraelectric phase (PE-KDP) and ferroelectrical phase (FE-KDP) crystals. Our calculations indicate that La K ·· is readily formed in both crystal structures, and the degree of H–O bond distortion is more pronounced in PE-KDP. This could explain the formation of small growth mounds on the surface of La-doped crystals observed in the experiments, as well as the large decrease in the hardness of La-doped crystals. Furthermore, the band gap value of La-doped crystals is smaller than that of perfect crystals. This can be attributed to the fact that the 5d orbitals of La affect the 2p orbitals of O located in the conduction band minimum (CBM), resulting in a splitting of the energy levels and the formation of a defective energy level that enters the forbidden band. The optical spectra have been obtained considering the electron-phonon coupling. Large stokes redshift and nonradiative jump will lower the crystal laser damage threshold. The La-doped PE-KDP has an absorption band at 3.03 eV (409 nm) in good agreement with the experimentally observed absorption band at 390 nm. [ABSTRACT FROM AUTHOR]

A family of Metalloborane of general formula Cp*3(μ‐H)M3B8H8 changing the metals M by Cr, Mo, and W, were theoretically studied via Density Functional Theory (DFT) incorporating the relativistic scalar (Scal) and spin‐orbit (SO) corrections. All the calculations agree with the experimental reports of the compound Cp*3(μ‐H)W3B8H8 and allowed us to describe the molecular and electronic structures of this family of Metalloborane. The electronic properties were modeled using reactivity indexes, Nucleus Independent Chemical Shift (NICS) indexes, Natural Bond Orbital (NBO), and other methods showing that the metallic core is aromatic. The spectroscopic properties were also studied via Time‐Dependent Density Functional Theory (TD‐DFT) showing a variation in the UV‐Vis spectra as the metallic atoms were changed. The most intense transitions are centered mainly over the metalloboranes cage with a decrease of the wavelengths as the metallic core gets bigger due to the increase of the HOMO‐LUMO gap. The Cp*‐Metalloborane core and the H‐Metalloborane core interactions were studied via the Morokuma‐Ziegler decomposition scheme, showing that the electrostatic interaction plays the most important role in the stabilization energy of the Cp*‐Metalloborane core. All our results suggest that the compound a (Cp*3(μ‐H)Cr3B8H8) and b (Cp*3(μ‐H)Mo3B8H8) will display similar properties to compound c (Cp*3(μ‐H)W3B8H8) and all of them are expected to have interesting properties. [ABSTRACT FROM AUTHOR]

In this research, we have explored the effect of Au:Cu ratio on the crystallographic and electronic structural properties, formation energies, and radial distribution function (RDF) of Au-Cu alloy materials via density functional calculations. The results show that Au-Cu alloy can be formed in any Au:Cu ratio from 3:1 to 1:3 with a similar possibility. The results also reveal that the lattice constants of both Au and Cu are affected by the LDA-PWC pseudo-field, which is in full agreement with the experimental findings. An increase in the concentration of Cu impurity in Au results in a decrement not only in the lattice constants of the crystal system but also in the total energy of the system (Etot). However, an enhancement in the electron density is determined by increasing Cu impurity concentration in Au. The RDF results confirm the contraction of lattice constants and a structural change in Au-Cu from cubic to tetrahedral is found when the Au:Cu ratio is equal to 1:1. These findings revealed in this work are expected to contribute to future studies on electronic materials. [ABSTRACT FROM AUTHOR]

This study investigated the energy band structure (BS), electronic state density, and optical properties of monolayer molybdenum disulfide (ML-MoS 2) with undoped, sulfur vacancy (V S), bromine (Br), and iodine (I) doped MoS 2 systems using the first-principle approach based on density functional theory (DFT). Our results show that compared to undoped MoS 2 system, Br, and I doped MoS 2 systems induced lattice distortions. In addition, and the bandgap widths was reduced in V S , Br, and I doped systems, thereby effectively suppressing the compounding of electron–hole pairs. Moreover, the recombination rate of electron–hole pairs was reduced, which in turn increased the mobility of electrons transferred from the valence band (VB) to the conduction band (CB). Moreover, the V S and Br doped systems exhibited superior optical properties compared to undoped MoS 2 system. Notably, the V S system exhibited the best optical properties, thereby demonstrating the strongest polarization capability. Our findings pave the way for realizing electronic devices and photocatalytic materials on MoS 2 nanostructures. [Display omitted] • Lattice distortion of monolayer MoS 2 by the introduction of V S , Br, and I doping elements. • The introduction of V S and Br doping element enhances the electron mobility of monolayer MoS 2. • The introduction of V S and Br doping element enhances the utilization of monolayer MoS 2 for infrared and visible light. [ABSTRACT FROM AUTHOR]

The investigations of the pressure effects on structural, elastic, electronic and optical properties of fluoride-perovskite NaBeF3 are carried out for the first time using the full-potential linearised augmented plane wave plus local orbitals (FP-LAPW + lo) implemented in the Wien2K code. Local density approximation, generalised gradient approximation (GGA), EV-GGA and modified Becke–Johnson (mBJ) approaches are adopted to incorporate the exchange and correlation potential. The calculated structural properties are in good agreement with the previous results. The predicted indirect band gap (R–Γ) is 11.87 eV for NaBeF3 indicating the insulating behaviour of the fluoride perovskite. The calculated formation and cohesion energies assert that this compound can be experimentally realised. The elastic properties indicate that NaBeF3 alloy is mechanically stable, ductile and anisotropic with a mixed bonding nature. The computed optical properties are in line with the Penn model and reveal its transparency for a large interval of energies. The investigation of the pressure effects on some physical properties of the studied alloy reveals that the compressibility module and the energy gaps increase with increasing pressure whereas the lattice constant decreases with increasing pressure. The investigated alloy can be used for high-frequency optical and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Half-metallic Heusler alloys are promising materials that present the character to remain essential for spintronics applications. In this paper, we carried out a DFT spin-polarized calculation to accurately predict structural, electronic, and magnetic properties of two new quaternary Heusler alloys; namely, the PdCoMnGa and PdCoMnAl. To this aim, we have used the generalized gradient approximation (GGA + SOC), for the exchange and correlation potentials. The results clearly showed that both structures were structurally stable in the ferromagnetic phase. The investigation of elastic and electronic properties of these alloys indicates the PdCoMn(Ga/Al) are mechanically stable and have half-metallic behavior. The total spin magnetic moments are found close to 5 µB/cell, confirming the half metallicity characteristic for both PdCoMnGa and PdCoMnAl. Further electronic analysis is also given to accurately explain the origin of such properties. [ABSTRACT FROM AUTHOR]

[Display omitted] Pentlandite (Fe,Ni) 9 S 8 is a promising transition-metal catalyst for the hydrogen evolution reaction. However, little is explained about the long activation process that has been observed in experiments, and its facet-dependent hydrogen evolution activity is still theoretically unrevealed. To explain some experimental phenomena and to guide subsequent studies, density functional theory calculations are used to study the main synthetic surfaces: (1 1 1) and (3 1 1) in this work. The results show that the small metal cube plays an important role in the surface stability, and it is suggested that such cubes remain intact during catalysis. The linking sites serve as a bridge across the metal cubes and are the main catalytic active sites for hydrogen evolution. This is because the metal cubes can tune the electronic structures of the linking sites, and then the free energy of the linking sites is optimized. The (3 1 1) surface is a composite surface that consists of (1 0 0) and (1 1 1) facets and has the profile of a step. A surface conversion between the (3 1 1) and (1 1 1) facets may occur when the cube layer length increases. Therefore, the active sites can be feasibly engineered by the surface structures, and this could be helpful in further applications of (Fe,Ni) 9 S 8. [ABSTRACT FROM AUTHOR]

With the intention to reveal the effect of the substitution, Ti-doped InSb alloy, we accomplished a first-principles prediction within the FPLAPW+lo method. We used GGA-PBEsol scheme attached with the improved TB-mBJ approach to predict structural, electronic, and magnetic properties of In1-xTixSb with concentration x = 0, 0.125, 0.25, 0.50, 0.75, 0.875, and 1. Our lattice parameters are found in favorable agreement with the available theoretical and experimental data. The calculation shows that all structures are energetically stable. The substitutional doping transforms the ionic character of the InSb compound in half-metallic ferromagnetic comportment for concentration x = 0, 0.125, 0.25, and 0.50, with a spin polarization of 100% at the Fermi level, and metallic nature for In0.25Ti0.75Sb and In0.125Ti0.875Sb. The total magnetic moments are also estimated at about 1 μB. In0.875Ti0.125Sb, In0.75Ti0.25Sb, and In0.50Ti0.50Sb have half-metallic ferromagnets comportment and they can be upcoming applicants for spintronics applications. [ABSTRACT FROM AUTHOR]

Due to their rich structural chemistry and enormous catalytic applications, TPA (tris(2-pyridylmethyl)amine) coordinated iron (Fe-TPA) complexes are widely studied as potent functional model in biomimetic area. We have done a thorough computational study on six diverse mononuclear and dinuclear FeII/FeIII-TPA complexes using density functional method. All the possible spin states for the six species were computed, and the ground state S value of these species was determined. The molecular structures, energetic profiles of spin states, electrostatic potentials, spin densities, and orbital energies of all the six complexes are reported. A comparative study among these six species was also done to gain insights about any sort of correlation in properties of these species. The observed variations as well as correlations in properties of the species are imputed to the diverse ligand substituents in Fe-TPA skeleton. Theoretical reactivity behavior was evaluated by doing frontier molecular orbital analysis for all the species by mapping HOMO-LUMO diagrams. Electrostatic potential surfaces were mapped to study charge energy distribution in the species. Our computed results are in well agreement with the experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • According to the principle of electrical neutrality, a defect cluster model of [Si P ' + Mg K• ] was constructed. • The defect clusters was corrected using the FNV method with DFT and the PBE-GGA exchange-correlation functional, and the band gap was adjusted using the HSE correction. • Detailed analysis encompasses lattice distortions, electronic structures, and optical properties of defect clusters. In this study, the defect formation energies, lattice distortions, electronic structures and optical properties for the KDP crystal with defect cluster [Mg K + Si P ] have been obtained by first-principles methods. The accurate defect formation energies have been obtained by corrected with FNV method. The lattice distortion indicate that the appearance of defect clusters causes Si and P atoms to surround magnesium, resulting in a lattice distortion as high as 34.2 %. Furthermore, an silicate structure emerges, possibly leading to a reduction in the crystal damage threshold. The electronic structures reveal that the emergence of new defect states in the band gap of the crystal with [Mg K + Si P ]' structure. These defect states cause the bottom of the conduction band to shift downwards, resulting in a decrease in the band gap. This is primarily attributed to the contributions from Mg-3 s and O-2p orbitals. This is self-consistent with the larger distortion around Mg in the lattice distortion. This is also a possible factor contributing to the decrease in the crystal damage threshold. The calculated optical spectra demonstrate that absorption peak values at 3.5 eV, 4.53 eV, 5.54 eV, 5.70 eV, and 5.81 eV, originating from defect clusters [Mg K + Si P ]. Therefore, it is conjectured that the presence of impurities magnesium and silicon may be one of the reasons for the reduction in the crystal damage threshold. [ABSTRACT FROM AUTHOR]

The presence of nodal points (NPs) and nodal lines (NLs) in the momentum space of topological materials is accompanied by many interesting properties. In this study, we predicted that an existing material ScPd with Pm3¯m-type structure would have closed NLs in the kx/y/z = 0 planes and one pair of triply degenerate NPs (TNPs) along the R-M-R′ paths, respectively, when the spin–orbit coupling (SOC) effect is not taken into consideration. Obvious nontrivial surface states were found around band-crossing points A, B, and C, which can be seen as good evidence for the topological signatures of ScPd metal. When the SOC effect was added, a TNP–Dirac NP (DNP) transition appeared along the R-M-R′ paths. Also, the band-crossing points belonging to the closed NL in the kx/y/z = 0 planes were gapped by the induction of SOC. However, the SOC-induced gaps were very small (

In spintronics, half-metallic materials (HMMs) with Dirac-like cones exhibit interesting physical properties such as massless Dirac fermions and full spin polarization. We combined first-principles calculations with the quasi-harmonic Debye model, and we proposed that the rhombohedral GdMnO3 is an HMM with multiple linear band crossings. The physical properties of GdMnO3 were studied thoroughly. Moreover, the changes of multiple linear band crossings and 100% spin polarization under spin-orbit coupling as well as the electron and hole doping were also investigated. It is noted that such spin-polarized HMMs with linear band crossings are still very rare in two-dimensional and three-dimensional materials.

Herein theoretical study, we designed sixteen conjugated arylated α, β unsaturated carbonyl thiophene based compounds by using density functional theory (DFT) and time-dependent (TD) density functional theory at modified Perdue Wang density functional MPW1PW91 functional with 6-31G (d, p) basis set. Ground and excited state geometries, electronic and photophysical characteristics of designed molecules are evaluated by assuming the electron-donating and electron-withdrawing effects of the substituents that are attached to these newly designed molecules. Furthermore, calculation of vibrational spectra, time-dependent effect, isotopic substitution effect and force constant along with thermodynamic quantities are also carried out by using MOPAC (Molecular Orbital Package) with strong implementation of semi empirical Hamiltonians. The results reveal that our designed molecules can be a good candidates for electroluminescent and optoelectronic devices for further fabrication of solar cell devices. [ABSTRACT FROM AUTHOR]

In this work, we have predicted the structural, electronic, and magnetic properties of the quaternary fluoro-elpasolite Rb2NaCrF6 alloy. We have performed our calculations by the use of first-principle methods developed on spin-polarized density functional theory, where the electronic exchange–correlation potential is evaluated by the generalized gradient approximation GGA-PBEsol coupled with the improved TB-mBJ approach. The calculated structural parameters of Rb2NaCrF6 are in good agreement with the available experimental data. Rb2NaCrF6 exhibits a half-metallic ferromagnetic feature with a spin polarization of 100% at the Fermi level and a direct large half-metallic gap of 2.04 eV. The total magnetic moments are 3μB. This compound is half-metallic ferromagnets, and it can be potential candidates for spintronics applications at a higher temperature. [ABSTRACT FROM AUTHOR]

In this work, we have predicted the structural, electronic, and magnetic properties of the quaternary fluoro-elpasolite Rb2NaCrF6 alloy. We have performed our calculations by the use of first-principle methods developed on spin-polarized density functional theory, where the electronic exchange–correlation potential is evaluated by the generalized gradient approximation GGA-PBEsol coupled with the improved TB-mBJ approach. The calculated structural parameters of Rb2NaCrF6 are in good agreement with the available experimental data. Rb2NaCrF6 exhibits a half-metallic ferromagnetic feature with a spin polarization of 100% at the Fermi level and a direct large half-metallic gap of 2.04 eV. The total magnetic moments are 3μB. This compound is half-metallic ferromagnets, and it can be potential candidates for spintronics applications at a higher temperature. [ABSTRACT FROM AUTHOR]

The Young's Modulus plot of the YMgNi 4 , and its hydrides YMgNi 4 H and YMgNi 4 H 4 is discussed. The addition of H makes the anisotropy of these materials more obvious. [Display omitted] • Mechanical, electronic, and thermodynamic properties were studied by DFT. • Analysis includes thermodynamic, dynamic, and mechanical stability of three alloys. • Elastic constants and modulus of three alloys were analyzed in detail. • Densities of state and difference charge density of three alloys were analyzed. • Free energy and heat capacity curves of three alloys were given. Using the Density Functional Theory, we investigated the mechanical, electronic, and thermodynamic properties of YMgNi 4 alloys and its two hydrides. The results of formation enthalpy and impurity formation energy indicate that an increase in H doping content contributes to the thermodynamic stability of YMgNi 4 alloy, and the phonon dispersion curves show that these models are consistent with dynamic stability. Additionally, the elastic modulus Poisson's ratio and AU were studied using the Voigt-Reuss-Hill approximation method. The band structures and density of states confirm their metallic nature. The free energy and heat capacity were also calculated to further investigate the thermodynamic properties. [ABSTRACT FROM AUTHOR]

Very recently, two R 3 − c Dirac half-metal materials, LaMnO 3 and MnF 3 , were found and investigated by Du et al. via first principles. They stated that these types of materials with half-metallic band structures and multiple linear band dispersions might exhibit excellent 100% spin polarization and ultrafast electron transport. However, the application of MnF 3 material in the field of spintronics is limited owing to its low Curie temperature (Tc). In this work, we proposed a new half-metal material—MnBO 3. This material satisfies two demands at the same time—it is a half-metal with a high Tc, and it has multiple nearly linear band crossings. The effects of the uniform strain, vacancies, spin–orbit coupling, as well as hole and electron doping on its electronic structures have been discussed in detail. Furthermore, to better study its specific behaviors under extreme conditions, such as high temperature or pressure, we also investigated the thermodynamic properties of MnBO 3 through the quasi-harmonic Debye model. Finally, its thermal stability at room temperature has been proved in this article by means of ab initio molecular dynamics (AIMD) simulations. We hope that MnBO 3 can attract more attention for R 3 − c -type half-metallic materials with linear band crossings and a high Curie temperature in experimental and theoretical areas. • We proposed a R 3 − c robust half-metal with multiple Dirac-like crossings. • The relatively high T c of MnBO 3 makes it more ideal for spintronic applications. • MnBO 3 is thermally stable at room temperature. • The 100% spin polarization comes from its unusual band structures. [ABSTRACT FROM AUTHOR]

A novel half-metallic family of materials, the multiple Dirac cones half-metals, has received considerable interest from researchers. Benefiting from its novel electronic structure, they are promising candidates for ultra-performance spintronic devices. In this paper, we propose a new half-metallic material, perovskite-type R 3 − c HoMnO3, which possesses similar Dirac-like multiple linear band crosses. We investigated its electronic, magnetic and thermodynamic properties in detail on the basis of density functional theory. The excellent band structures are robust enough against spin-orbit coupling and electron and hole doping. Through calculations, we confirmed its multi-aspect stability. Based on the current study, we confirm that HoMnO3 has potential for next-generation spintronic applications. [ABSTRACT FROM AUTHOR]

In recent years, the search for new Dirac half-metallic materials has been one of the hotspots in the field of spintronics because they have very good physical properties, such as massless Dirac fermions and full spin polarization. In this study, using density function theory combined with the quasi-harmonic Debye model, we show that perovskite-type dysprosium manganite is a novel half metal with multiple Dirac cones. A detailed study of the electronic, magnetic, and thermodynamic properties of DyMnO 3 was carried out. Furthermore, the effects of uniform strain, the on-site Coulomb interaction U , spin-orbit coupling, and hole and electron doping on the multiple Dirac cones and full spin polarization were investigated. We should point out that such a spin-polarized Dirac material is rare among perovskite-type compounds. Hence, we hope that, through this work, this kind of material will receive more extensive attention in future studies. In this study, using density function theory combined with the quasi-harmonic Debye model, we show that perovskite-type dysprosium manganite is a novel half metal with multiple Dirac cones. Moreover, in order to test whether the material has a long spin coherence length, we studied the effect of SOC on the band structure. Image 1 [ABSTRACT FROM AUTHOR]

In this study, we have employed the first-principle methods based on spin-polarized density functional theory to investigate the structural parameters, the electronic structures, and the half-metallic ferromagnetic behavior of chromium (Cr)-doped barium selenide (BaSe) such as Ba1 − xCrxSe at concentrations x = 0.25, 0.5, and 0.75. The exchange and correlation potential is described by the generalized gradient approximation of Wu and Cohen (GGA-WC). The calculated structural parameters of BaSe are in good agreement with theoretical data. Our findings reveal that the p-d exchange coupling is ferromagnetic for Ba0.75Cr0.25Se and Ba0.5Cr0.5S, but it becomes anti-ferromagnetic for Ba0.25Cr0.75S. The electronic structures exhibit that the Ba1 − xCrxSe materials for all concentrations are half-metallic ferromagnets with spin polarization of 100% and total magnetic moment per Cr atom of 4 μB. Therefore, the Ba1 − xCrxSe compounds are suitable candidates for possible spintronics applications. [ABSTRACT FROM AUTHOR]

Abstract The hydrogen adsorptions on 2H-phased Mo X 2 (X = S, Se) monolayers as a function of biaxial strain or external vertical electric field were investigated on the basis of density-functional theory. The results show the intrinsic bandgap and electron transfer effects on the hydrogen adsorption of Mo X 2 monolayer, which reveal the relationship between the electronic structures of Mo X 2 and corresponding hydrogen adsorption behaviors. Both biaxial strain and external vertical electric field have the ability to change bandgap of Mo X 2 monolayer. Bandgap narrowing can lead to hydrogen adsorption strengthening. The hydrogen adsorption on Mo X 2 monolayer can also be finely tuned by an electron transfer between H adatom and substrate by means of vertical electric field. Therefore, we suggest that these two factors can possibly be regulated and synergistically tune the hydrogen adsorption on Mo X 2 monolayer. Highlights • The mechanism of H adsorption on MoS 2 (MoSe 2) monolayer versus biaxial strain/electric field is explored. • The relationship between intrinsic electronic structures and H adsorption behaviors is investigated systematically. • The behavior of H adsorption tightly related to HER activity can be tuned by biaxial strain/electric field. [ABSTRACT FROM AUTHOR]

First-principles method was employed to study the defect formation energy, electronic structure, and optical properties of Potassium Dihydrogen Phosphate (KDP) crystals doped with Mg in both paraelectric phase (PE-KDP) and ferroelectric phase (FE-KDP). Additionally, we employed the HSE hybrid density functional to address the issue of "band gap" and utilized the finite size correction-finite volume (FNV) method to rectify defect formation energies. Due to hybridization of Mg-3s orbitals with O-2p orbitals, a defect energy level is created at the conduction band minimum (CBM), resulting in the band gap of Mg-doped KDP crystals being smaller than that of perfect crystals. Moreover, the incorporation of Mg leads to significant lattice distortions and alters bond lengths, particularly the O–Mg bonds, which are stretched by 0.65–0.77 Å. The optical spectra also have been obtained under the consideration of electron-phonon coupling. The absorption peak locates at 4.37 eV (284 nm) in PE-KDP. The absorption peak locates at 4.66 eV (266 nm) in FE-KDP. Moreover, the significant Stokes shifts (3.67 eV and 2.9 eV) observed in Mg-doped KDP crystals were attributed to lattice relaxation energy and distortions induced by the substitution. The calculated results indicate that the quality of the KDP crystals may be reduce by introducing Mg-impurities. The work provides valuable insights into the optical characteristics of Mg-doped KDP crystals and their potential applications in laser technology. [ABSTRACT FROM AUTHOR]

Theoretical studies have been carried out to predict the structure, electronic, optical and photovoltaic properties of systems based on carbazole - thiophene bridged and X groups (X1: Benzo-[c]-thiophene, X2: Quinolinn-8-ylamine, X3: Benzyl-amine) with or without the strongly attracting chromophore -CHCO2HCN. The optoelectronic and photovoltaic properties improve when some donor and acceptor blocs alternate on the oligomer skeleton since slight band gap are noticed especially for X2 and X3 molecules with chromophore (average value 2.59eV). Indeed, some higher values of λmax (wave-length absorbed) are obtained and the HOMO and LUMO orbitals are correctly located than their homologs semi-conductors like the bis adduct of phenyl-C61-butyric acid methyl ester (Bis-PC61BM). DOI: http://dx.doi.org/10.17807/orbital.v10i7.1322

Abstract Hydrates of HCl, HNO 3 and H 2 SO 4 involved in polar stratospheric clouds capture the attention of researchers due to the mixtures composed with them. The molecular aggregates generated with these strong acids show different behaviors, geometries and nucleation reactions at atmospheric temperatures. Here is presented a systematic ab initio optimization study of monohydrates of HCl•HNO 3 •H 2 SO 4 using the Density Functional Theory, by means of geometry optimizations carried out with B3LYP hybrid method and aug-cc-pVTZ basis set, a high level of theory, within Gaussian 09 program. This systematic optimization procedure consists to situate systematically the H 2 O molecule around the cluster in study, on the favorable positions to develop higher quantity of hydrogen bonds as possible, in order to obtain major quantity of different electronic structures of these monohydrates. Applying this systematic optimization methodology over previously optimized complexes of HCl, HNO 3 and H 2 SO 4 , the present theoretical approach provides thirty-two different optimized electronic structures of monohydrates that were yielded from seven initial groups of (HCl•HNO 3 •H 2 SO 4)-complex, placing the H 2 O in eight positions around them. Moreover, their Infrared spectra have been predicted for all (HCl•HNO 3 •H 2 SO 4)-monohydrates achieved. Likewise, It is shown the outcomes of the electronic energies, relative Gibbs free energies, Infrared spectra, the wavenumbers of hydrogen bonds, inter-monomeric parameters, electronic structures of (HCl•HNO 3 •H 2 SO 4)-monohydrates. These monohydrates could be considered precursors of the atmospheric heterogeneous nucleation reactions. These results can be useful to experimentalists of Catalysis, Astrophysics, Corrosion of metals and ceramics, aromatic compounds reactions, even environmental pollution and industrial smog. Graphical abstract Heterogeneous atmospheric reactions implicated in ozone depletion remain unknown. The stratospheric nucleation reactions are an aim for both experimental and theoretical researchers, mainly the heterogeneous nucleation reactions where the HCl, HNO 3 and H 2 SO 4 molecules are involved. The ab initio electronic structure optimizations for (HCl•HNO 3 •H 2 SO 4)-monohydrates have been carried out applying an ab initio systematic optimization procedure. The different H 2 O molecule positions around of each one of the seven (HCl•HNO 3 •H 2 SO 4)-complexes provide accurately fifty-six optimized (CNS-K+1W I)-monohydrates. All electronic structures optimizations have carried out by means of DFT method alongside the aug-cc-pVTZ of Dunning's basis set. The geometries optimizations offer the global minimum and relative minima structures for each one of (CNS-K+1W I)-monohydrates optimized. Thirty-two different electronic structures of (HCl•HNO 3 •H 2 SO 4)-monohydrates have been achieved from fifty-six optimized monohydrates geometries. Besides, the hydrogen bond interactions have been predicted in the infrared spectra for all (CNS-K+1W I)-monohydrates, whose outcomes are in consonance with experimental data. As well as, the relative electronic and relative Gibbs free energies, the inter-monomeric hydrogen bonds, and this inter-, and intra-monomeric parameters have been obtained. This theoretical approach can be useful to experimentalist in fields like Atmospheric Chemistry, Climate Change, Environmental Pollution, Astrophysics, and Catalysis, Corrosion of metals and ceramics, and reactions of aromatic compounds. This systematic ab initio optimization method guarantees to reach all different electronic structures for any molecular system optimized. IR spectra of each global minima for each one of (HCl•HNO 3 •H 2 SO 4)-monohydrates or (CNS- K +1W i). Image 1 Highlights • Systematic ab initio optimization procedure to achieve electronic structures with DFT method. • Ab initio optimizations of (HCl·HNO 3 ·H 2 SO 4)-monohydrates geometries. • Thirty-two different electronic structures of (CNS-K+1Wi)-monohydrates optimized. • Infrared spectra and inter-monomeric hydrogen bonds for each (CNS-K+1Wi)-monohydrate. • Geometries, hexagonal ring, electronic and Gibbs free energies of each monohydrate. [ABSTRACT FROM AUTHOR]

Theoretical studies have been carried out to predict the structure, electronic, optical and photovoltaic properties of systems based on carbazole - thiophene bridged and X groups (X1: Benzo-[c]-thiophene, X2: Quinolinn-8-ylamine, X3: Benzyl-amine) with or without the strongly attracting chromophore -CHCO2HCN. The optoelectronic and photovoltaic properties improve when some donor and acceptor blocs alternate on the oligomer skeleton since slight band gap are noticed especially for X2 and X3 molecules with chromophore (average value 2.59eV). Indeed, some higher values of λmax (wave-length absorbed) are obtained and the HOMO and LUMO orbitals are correctly located than their homologs semi-conductors like the bis adduct of phenyl-C61-butyric acid methyl ester (Bis-PC61BM). [ABSTRACT FROM AUTHOR]

New diorganotin(IV) derivatives of sparfloxacin having general formula R 2 SnCl(L), (where L = monoanion of sparfloxacin (HL) and R =  n -Bu ( 1 )/Ph ( 2) ) have been synthesized and structurally characterized by elemental analysis, IR, NMR ( 1 H, 13 C, 119 Sn), HMQC, ESI-MS, UV–Vis and emission spectroscopy. These investigations suggest that, in these 1:1 monomeric derivatives the sparfloxacin ligand acts as monoanionic bidentate coordinating through the O carboxylate and O pyridone , and the polyhedron around tin is intermediate between pseudotetrahedral and cis -trigonal bipyramidal. The proposed structures have been validated by density functional theory (DFT) based electronic structure calculations at B3LYP/6-31G(d,p)/Def2-SVP(Sn) level of theory through the calculation of the atomic charges at the selected atoms, molecular electrostatic potential (MEP) map to assign sites on the surface of the molecules, the selected conceptual-DFT based global reactivity descriptors to obtain an insight into the structure and reactivity behaviour, and the frontier molecular orbital analysis to analyze the nature of frontier orbitals. A comparative analysis of the experimental vibrational frequencies and simulated harmonic frequencies indicates good correlation between them. The simulated UV–Vis spectrum was obtained with time dependent-DFT method in gas phase and in the solvent field with IEFPCM model. The simulated 1 H and 13 C NMR spectra were obtained by gauge-independent atomic orbital (GIAO) method and the results were in good agreement to the experimental results. The complexes were screened for their in vitro antibacterial activity against two Gram-positive and five Gram-negative bacterial strains. Both the complexes exhibited promising antibacterial activity against all the chosen strains (MIC: 0.062–0.125 μg ml −1 ). [ABSTRACT FROM AUTHOR]

The fluorination of the attached phenyl groups and the introduction of –CF 3 moieties in the phenyltriazole cyclometallated ligands results in a strong interaction in the T 1 states, due to the contracted Ir–Ns bonds with the bpy ancillary ligand. Therefore, both complexes show a moderate contribution of the metal character (% M c), a lower energy gap between the S 1 and the T 1 states Δ E S1-T1) along with the largest transition dipole moment (μ S1), resulting in an enhanced phosphorescence quantum efficiency. [Display omitted] The electronic structure, absorption properties, phosphorescence quantum efficiency and emission spectra, of a series of iridium(III) complexes containing phenyltriazole-type cyclometallated ligands (1 – 4) were studied using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The simulated electronic/photophysical properties of the iridium complexes are in good agreement with the experimental observations. The results of the calculations show that the lowest lying singlet absorptions for 1 – 4 are located at 3.83, 3.91, 3.01, and 2.98 eV, respectively. All complexes show emissions characterised as a mixture of triplet ligand-to-ligand charge transfer (3LLCT) and metal-to-ligand charge transfer (3MLCT) states. The fluorination of the attached phenyl groups (complex 2) and the introduction of –CF 3 moieties (complex 3) in the phenyltriazole cyclometallated ligands results in a strong interaction in the T 1 states, due to the contracted Ir–Ns bonds with the bpy ancillary ligand. Therefore, both complexes show a moderate contribution of the metal character (% M c), a lower energy gap between the T 1 and the S 1 states (ΔE T1-S1) together with the largest transition dipole moment (μ S1), resulting in an enhanced phosphorescence quantum efficiency. The introduction of –CH 3 groups (complex 4) in the phenyltriazole cyclometallated ligands stabilises the triplet metal-centred (3MC) state, resulting in a fast nonradiative decay along with a lower quantum yield. The vertical emission energies calculated at the B3LYP level for the 1–4 complexes are located at 2.60, 2.38, 2.68, and 2.62 eV, respectively. Based on these results, the theoretical calculations can provide an accurate prediction of the electronic and the photophysical properties of iridium complexes, and then can be used to guide the synthesis of new phosphorescent materials. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, we have investigated the growth mode, magnetic and electronic properties of Fe n clusters (n = 1 – 10 , 13) on graphdiyne (GDY) surface. The small-size Fe n with n ≤ 3 clusters adsorbed on the surface of GDY favor a planar configuration and other clusters with n > 3 have three-dimensional structures. The original morphology was maintained upon adsorption on the GDY surface. The Fe n clusters with n = 3 – 6 , 13 tend to bind with the surface with the lower adsorption energy. The relative stability of Fe n clusters was not changed upon the adsorption. The remarkable charge transfers from the neighboring Fe atoms to the GDY surface account for the strong interactions of Fe n with GDY. The magnetic moments of the adsorbed clusters were significantly reduced compared with free clusters. The adsorption of Fe n clusters improves the conductivity of GDY. • The Fe n clusters with n = 3 – 6 , 13 tend to bind with the surface with the lower adsorption energy. • The relative stability of Fe n clusters was not changed upon the adsorption. • The strong interactions of Fe n with GDY are ascribed to the remarkable charge transfers. • The adsorption of Fe n clusters improves the conductivity of GDY. • The magnetic moments of the adsorbed clusters were significantly reduced. [ABSTRACT FROM AUTHOR]

Both Mg and Mg2Ni are promising electrode materials in conversion-type secondary batteries. Earlier studies have shown their single-phase prospects in electro-devices, while in this work, we have quantitatively reported the electronic properties of their dual-phase materials, that is, Mg-Mg2Ni alloys, and analyzed the underlying reasons behind the property changes of materials. The hypoeutectic Mg-Mg2Ni alloys are found to be evidently more conductive than the hypereutectic Mg-Mg2Ni system. The density functional theory (DFT) calculations give the intrinsic origin of electronic structures of both Mg2Ni and Mg. The morphology of quasi-nanoscale eutectics is another factor that can affect the electronic properties of the investigated alloy system; that is, the electrical property change of the investigated alloys system is due to a combination of the intrinsic property difference between the two constituting phases and the change of eutectic microstructures that affect electron scattering. In addition, regarding the Mg-Mg2Ni alloy design for device applications, the electronic property and mechanical aspect should be well balanced. [ABSTRACT FROM AUTHOR]

Two compounds 1-[(2-carboxymethyl)benzene]-3-[2-pyridine]triazene (HL) and 1-[(2-carboxymethyl) benzene]-3-[ o-aminobenzoic acid]triazene (HL') and two corresponding Pt(II) complexes, Pt(PPh)(L)Cl ( 1) and Pt(PPh)(L') ( 2), are theoretically studied by the density functional theory and time-dependent density functional theory. The geometric structure of complex 1 is optimized by B3LYP, PBE0, and M06 methods with the same mixed 6-31G(d)-LANL2DZ basis set. The absorption spectrum of complex 1 is simulated by the above method. As compared with the experimental data, the combination of M06/6-31G(d)-LANL2DZ and TD-M06/6-31G(d)-LANL2DZ is chosen for all other calculations including optimization of the ground-state and the lowest triplet excited state geometries, and the absorption and emission spectra. The detailed electronic transitions are analyzed to understand deeply the properties of spectra. Mobility of holes and electrons in 2 are studied computationally based on the Marcus theory. The ionization potential and electron affinity of complex 2 are calculated to evaluate qualitatively the hole- and electron-injection properties, respectively. Its potential as a dopant for phosphorescent OLEDs is explored. [ABSTRACT FROM AUTHOR]

We have used the first-principle calculations of density functional theory within full-potential linearized augmented plane-wave method to investigate the electronic and ferromagnetic properties of $$\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}$$ alloys. The electronic structures of $$\hbox {Al}_{0.25}\hbox {V}_{0.75}\hbox {Sb}, \hbox {Al}_{0.5}\hbox {V}_{0.5}\hbox {Sb}$$ and $$\hbox {Al}_{0.75}\hbox {V}_{0.25}\hbox {Sb}$$ exhibit a half-metallic ferromagnetic character with spin polarization of 100 %. The total magnetic moment per V atom for each compound is integral Bohr magneton of 2 $$\mu _{\mathrm{B}}$$ , confirming the half-metallic feature of $$\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}$$ . Therefore, these materials are half-metallic ferromagnets useful for possible spintronics applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dispersion corrected hybrid B3LYP-D2 functional was employed on transition metal Mn/Fe/Co complexes. • Bonding aspects are analyzed using NBO and EDA. • Electronic transitions are discussed using TDDFT computation. • Photophysical properties are computed. • Light harvesting efficiency are calculated. In the realm of dye sensitized solar cells (DSSCs), the 3d transition metals as photosensitizers are scarcely studied. In the present work, electronic structures, FMO, MEP surfaces, NBO analysis, energetics and photophysical properties of earth abundant metals (Mn, Fe and Co) based metalloporphyrins coordinated with NHC-carbene have been explored by using DFT and TDDFT calculations. According to formation energies and energy decomposition analysis (EDA), the cobalt based metalloporphyrins species are found to be more stable while in contrast manganese based species are predicted as more reactive among all. Also, from the ligation point of view, the TPP (meso -tetraphenylporphyrin) ligand forms more steady and rigid coordination as compare to the TTP (meso -tetratolylporphyrin) ligand. FMO analysis also support these observations. NBO and SNO results support the electronic configurations as well as unveil the controversial bonding pattern of NHC carbon and metal atom and found that there is σ -bonding present between the metal and the NHC carbon by the overlapping of sp -hybridized orbitals of carbene carbon and sp / d hybrid orbital of the metal atom. TDDFT results show that the highest light harvesting efficiency (LHE) of all the studied species is found under the range of 360 nm − 380 nm (λ) and this may due to the presence of longer π-conjugations. In-depth investigation of this work may help to design new robust energy harvesting systems for high energy conversion efficiency based on earth abundance metals. Our results are in well agreement with the available experimental findings. [ABSTRACT FROM AUTHOR]

In this theoretical study, the monolayer carbon allotrope, Me-graphene (also called C568), was respectively doped with Al, Si, P, and Ge atoms by substituting the s p 3 -hybridized carbon atom in its unit cell to manipulate its physical properties. Theoretical calculations based on the density functional theory (DFT) confirmed the dynamic stabilities of the related doping systems. Interestingly, the mechanical strengths of the doping systems are even stronger than the pristine one. After doping with Si atom, the band gap of the Me-graphene system narrowed from 1.097 eV to 0.987 eV estimated at HSE06 level. However, the Ge-dopant at the s p 3 -site has very limited influence on the band gap. In the other two cases with Al and P dopants, the systems changed to be metallic because their Fermi levels cut into the valence bands to a certain extent. Additionally, the adsorption sites of Li atoms and the energy profiles of the Li migrations on the related 2D material systems were also investigated in order to reveal their application potentials as anodes in lithium-ion batteries (LIBs). [Display omitted] • The sp3 -hybridized carbon in Me-graphene is substituted with Al, Si, P, and Ge atoms. • A quasi-flat plane is obtained by doping Al-atom at sp3 site in Me-graphene. • The mechanical strength are even enhanced by doping at sp3 site in Me-graphene. • The application potentials of the doped Me-graphene as anodes in LIBs were theoretically evaluated. [ABSTRACT FROM AUTHOR]

In this work, a new orthorhombic Mg 2 SiO 4 had been predicted by ab -MD and DFT methods. Stability criterion test proved the new phase was possibly and really existing under high pressure. In new predicted phase, besides covalent interaction between Si-3 p (outer shell electrons of Si) and O-2 p , covalent interaction between Si-2 p electrons (inner shell electrons of Si) and O-2 s was observed too. One Si and six nearest O atoms formed six Si–O covalent bonds, and built up an uncommon Si–O octahedron. Studies of mechanical properties showed that Mg 2 SiO 4 has excellent stress tolerance. However, shear resistant of Mg 2 SiO 4 was less ideal. Under the condition of continuous pressure, compressional and shear wave velocities increased with pressure discontinuously obviously. [ABSTRACT FROM AUTHOR]

In this article, the nanotubes obtained by silicon atoms substitutionally doping the single-walled carbon nanotubes were investigated by quantum chemistry calculations under the framework of density functional theory. The geometrical structures, relative stabilities and electronic properties of the Si-doped tubes were studied in details and compared with those of the pristine (12, 0) tubes. It is found that the Si atoms in the doped tubes have obviously larger π-orbital axis vector angles than carbon atoms, and they also tend to “pop out” from the original positions. The Si-doped nanotubes exhibit lower thermodynamic stability than those of the undoped tubes from the viewpoint of both cohesive energy and Gibbs free energy. The energy levels of the frontier orbitals vary within 0.25 eV when the silicon atom is introduced into the nanotubes. However, most hybrid nanotubes present larger energy gaps than those of the pristine ones. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic structures of homo and hetero valent dinuclear transition metal species were investigated. • Correlation has been figure out between d-electrons and M−M bond length of dinuclear species. • Iso densities over the molecules were discussed through frontier molecular orbitals. • NBO analysis shows the dominant donor–acceptor interactions. • Charge transfer and d-d transition were also analysed by computation of UV–Vis. Bridged dinuclear metal complexes have fascinated scientists worldwide, and remarkable success has been achieved to unravel the electronic structures, structure–function relationship, coordination environments, and fine mechanistic details of the enzymes owing to the repercussion of biomimetic studies carried out on dinuclear model systems. Molecular level study of these systems integrated with spectroscopic study helps in gaining deep insights about structural and electronic aspects of natural enzymatic systems. Considering the same, here first time we report DFT study on bridged non-heme metal complexes based on N-Et-HPTB ligand system containing homovalent (MIIMII); {[(MnII) 2 (O 2 CCH 3)(N-Et-HPTB)]2+; Species I), [(FeII) 2 (O 2 CCH 3)(N-Et-HPTB)]2+; Species II), [(CoII) 2 (O 2 CCH 3)(N-Et-HPTB)]2+; Species III)} and heterovalent (MIIIMII): {[(MnIII)(MnII)(O 2)(N-Et-HPTB)]2+; Species Ia) [(FeIII)(FeII)(O 2)(N-Et-HPTB)]2+; Species IIa) and [(CoIII)(CoII)(O 2)(N-Et-HPTB)]2+; Species IIIa) } dinuclear metal centres. Bridging oxygen bears a significant spin density which may prompt important chemical reactions involving activation of bonds like C-H/O-H/N-H etc. TD-DFT calculations for UV–Visible absorption have been carried out to further shed light on structural–functional and electronic structures of these dinuclear species. Studying these dinuclear species may be a good starting point for the study of active sites of the bimetallic centre of dinuclear enzymes and thus may serve as fascinating spectroscopic models. Further, FMO analysis, MEP mapping, and NBO calculations were employed to analyze bonding aspects predict theoretical reactivity behaviour and any kind of stabilizing interactions present in the reported species. [ABSTRACT FROM AUTHOR]

Two newly designed penta-silicon carbides, namely p-SiC 10 and p-Si 4 C 7 , are proposed in this work with the aid of density functional theory (DFT) simulations. Their structural stabilities are verified from energetic, lattice dynamic, and mechanical aspects. These systems possess low mass densities owing to the big interior spaces inherited from the host (i.e., pentadiamond), and relatively high mechanical strengths. The substitutions of the s p 3 carbon atoms by silicon in pentadiamond results in the narrowing of the energy band gaps from 3.78 eV to 3.18 eV and 2.81 eV in p-SiC 10 and p-Si 4 C 7 lattices at HSE06 level, respectively. Moreover, the band gap changes from indirect in pentadiamond into quasi-direct in p-SiC 10. These advantages make p-SiC 10 and p-Si 4 C 7 materials be promising candidates in semiconductor industry and aerospace field. [Display omitted] • Two new silicon carbides are proposed by Si-substitutions in pentadiamond. • The band gaps are 3.18 eV and 2.81 eV in the designed penta-silicon carbides. • The quasi-direct band gap in p-Si4C7 benefits the carrier separation. • The low densities and high strengths imply their applications with weight advantage. [ABSTRACT FROM AUTHOR]

Abstract: Density functional theory (DFT) calculations have been performed on electronic structures of 11 middle-infrared (mid-IR) nonlinear optical quaternary sulfides: Ln 4GaSbS9 (Ln=Ce–Nd, Sm, Gd–Tm, Lu). Our results show that Ln 4GaSbS9 are indirect gap semiconductors with a slight band gap increase from Ce to Lu. Their linear optical properties, including refractive index, absorption coefficient and energy loss function, as well as the nonlinear optical coefficients including static d 31, d 32, d 33 and dynamic d 32, are calculated. More importantly, the strong SHG response of Ln 4GaSbS9 can be attributed to the electronic transitions from S 3p states in valence bands (VB) to Sb–S and Ln–S antibonding states (CB). [Copyright &y& Elsevier]

Based upon extensive density functional theory and wave function theory calculations performed in this work, we predict the existence of the perfectly planar triangle C BH ( 1, A′) and the double-chain stripe C BH ( 9, A) which are the ground states of the systems and the inorganic analogues of cyclopropene cation D CH and cyclobutadiene D CH, respectively. Detailed adaptive natural density partitioning (AdNDP) analyses indicate that C BH is π plus σ doubly aromatic with two delocalized π-electrons and six delocalized σ-electrons formally conforming to the 4n + 2 aromatic rule, while C BH is π antiaromatic and σ aromatic with four delocalized π-electrons and ten delocalized σ-electrons. The perfectly planar C BH ( 5, A) also proves to be π antiaromatic analogous to D CH, but it appears to be a local minimum about 50 kJ mol less stable than the three dimensional C BH ( 6, A′). AdNDP, nucleus independent chemical shifts (NICS) and electron localization function (ELF) analyses indicate that these boron hydride clusters form islands of both σ- and π-aromaticities and are overall aromatic in nature in ELF aromatic criteria. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: From pseudo-potentials and all-electrons computations within density functional theory, desorption energies within range of MgH2 and covalent like hydrogenated intermetallic compounds are identified for hydrogen rich Mg3TH7, (T = Mn, Re). The rhenium based compound is found with a lower desorption energy which has been quantified from the analysis of the Bader charges within the {TH6}5- complex anion as related with a decreasingly ionic charge on hydrogen from Mn to Re. The electronic densities of states show insulating compounds in agreement with literature relevant to this class of salt-like hydrides with a larger band gap for the Re compound. From chemical bonding analyses stronger Mn–H bonding versus Re–H is identified in agreement with desorption energies magnitudes favoring Mg3ReH7. [Copyright &y& Elsevier]