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The intrinsic anomalous Hall effect in ferromagnetic materials depends on the spin–orbit-coupling-induced effect in the electronic structure. The presence of anomalous Hall effect can be realized from the existence of the finite Berry curvature. Since the Heusler material Pt2MnGa is ferromagnetic in its collinear state and no report on its transport properties has yet been made, the anomalous Hall effect in this system is investigated using a combined approach of the density functional theory and maximally localized Wannier function. Analysis of the Berry curvature reveals positive and negative peaks along the high symmetry k-points. These peaks together lead to a significant negative anomalous Hall conductivity, which makes the material a promising candidate for applications in spintronics. [ABSTRACT FROM AUTHOR]

MoSi2N4 is a two-dimensional ternary nitride semiconductor that has attracted attention for its excellent mechanical and thermal properties. Theoretical studies predict that zigzag edges of this material can host magnetic edge states and Dirac fermions, but the stability of such edges has not been examined. Here, we present a density functional theory study of the electronic and thermodynamic properties of MoSi2N4 edges. We develop a (partial) ternary phase diagram that identifies a region of chemical potentials within which MoSi2N4 is stable over competing elemental or binary phases. Based on this phase diagram, we determine the thermodynamic stability of several armchair and zigzag edges and elucidate their electronic structures. Bare zigzag edges, predicted to host exotic electronic states, are found to be substantially higher in energy than armchair edges and, thus, unlikely to occur in practice. However, with hydrogen passivation, these zigzag edges can be stabilized relative to their armchair counterparts while retaining metallicity and magnetic order. Our analysis provides a solid thermodynamic basis for further exploration of MoSi2N4 in nanoscale electronics and spintronics. [ABSTRACT FROM AUTHOR]

MoSi2N4 is a two-dimensional ternary nitride semiconductor that has attracted attention for its excellent mechanical and thermal properties. Theoretical studies predict that zigzag edges of this material can host magnetic edge states and Dirac fermions, but the stability of such edges has not been examined. Here, we present a density functional theory study of the electronic and thermodynamic properties of MoSi2N4 edges. We develop a (partial) ternary phase diagram that identifies a region of chemical potentials within which MoSi2N4 is stable over competing elemental or binary phases. Based on this phase diagram, we determine the thermodynamic stability of several armchair and zigzag edges and elucidate their electronic structures. Bare zigzag edges, predicted to host exotic electronic states, are found to be substantially higher in energy than armchair edges and, thus, unlikely to occur in practice. However, with hydrogen passivation, these zigzag edges can be stabilized relative to their armchair counterparts while retaining metallicity and magnetic order. Our analysis provides a solid thermodynamic basis for further exploration of MoSi2N4 in nanoscale electronics and spintronics. [ABSTRACT FROM AUTHOR]

Herein, we explore, from a theoretical perspective, the nonradiative photoinduced processes (charge separation and energy transfer) within a family of donor–acceptor supramolecular complexes based on the electron-donor truxene-tetrathiafulvalene (truxTTF) derivative and a series of curved fullerene fragments (buckybowls) of different shapes and sizes (C30H12, C32H12, and C38H14) as electron acceptors that successfully combine with truxTTF via non-covalent interactions. The resulting supramolecular complexes (truxTTF·C30H12, truxTTF·C32H12, and truxTTF·C38H14) undergo charge-separation processes upon photoexcitation through charge-transfer states involving the donor and acceptor units. Despite the not so different size of the buckybowls, they present noticeable differences in the charge-separation efficiency owing to a complex decay post-photoexcitation mechanism involving several low-lying excited states of different natures (local and charge-transfer excitations), all closely spaced in energy. In this intricate scenario, we have adopted a theoretical approach combining electronic structure calculations at (time-dependent) density functional theory, a multistate multifragment diabatization method, the Marcus–Levitch–Jortner semiclassical rate expression, and a kinetic model to estimate the charge separation rate constants of the supramolecular heterodimers. Our outcomes highlight that the efficiency of the photoinduced charge-separation process increases with the extension of the buckybowl backbone. The supramolecular heterodimer with the largest buckybowl (truxTTF·C38H14) displays multiple and efficient electron-transfer pathways, providing a global photoinduced charge separation in the ultrafast time scale in line with the experimental findings. The study reported indicates that modifications in the shape and size of buckybowl systems can give rise to attractive novel acceptors for potential photovoltaic applications. [ABSTRACT FROM AUTHOR]

The interplay between orientation transition and chiral self-assemblies of para-terphenyl (P3P) molecules on the Cd(0001) surface has been investigated using low temperature scanning tunneling microscopy and density functional theory calculations. Three distinct molecular orientations have been discerned from the self-assembled thin films of P3P. At the low coverage, flat-lying molecules appear in the homochiral domains with the incommensurate registry to the substrate. With the coverage increasing, the incoming molecules are incorporated into the first layer with edge-on orientation and form the self-assembled zigzag chains. The alternative arrangement of zigzag chains with opposite chirality leads to the formation of a c(4 × 2) superstructure, in which the tilted molecules exhibit orientational frustration and fuzzy noises. The analysis of the tunneling spectra reveals that the electronic structure of P3P layers is contingent upon the hybridization between the electronic states of P3P molecules and the Cd(0001) surface. These results provide important insights into the interplay between orientational transition and chiral assembly of P3P molecules on metal substrates. [ABSTRACT FROM AUTHOR]

We present an exchange–correlation approximation in which the Coulomb interaction is split into long- and short-range components and the range separation is determined by a non-empirical density functional. The functional respects important constraints, such as the homogeneous and slowly varying density limits, leads to the correct long-range potential, and eliminates one-electron self-interaction. Our approach is designed for spectroscopic purposes and closely approximates the piecewise linearity of the energy as a function of the particle number. The functional's accuracy for predicting the fundamental gap in generalized Kohn–Sham theory is demonstrated for a large number of systems, including organic semiconductors with a notoriously difficult electronic structure. [ABSTRACT FROM AUTHOR]

This study presents a collaborative experimental and theoretical investigation into the structures and electronic properties of niobium-doped germanium clusters. Anion photoelectron spectra for Nb1–2Gen− (n = 3–7) clusters were acquired using 266 nm photon energies, enabling the determination of adiabatic detachment energies and vertical detachment energies. In conjunction with these experimental measurements, density functional theory (DFT) calculations were conducted to validate the experimentally obtained electron detachment energies and elucidate the geometric and electronic structures of each anionic cluster. The agreement between DFT calculations and experimental data establishes a solid foundation for assessing the structural evolution and electronic properties of niobium-doped germanium clusters. It is noted that both neutral and anionic clusters exhibit predominantly similar overall structural characteristics, with the exception of Nb2Ge6− and Nb2Ge6. Furthermore, this investigation emphasizes the exceptional chemical stability of the D3d symmetric chair-shaped structure in Nb2Ge6−, providing insights into its bonding characteristics. [ABSTRACT FROM AUTHOR]

The photochromic behavior of the fulgide molecule relies on ring-closure and ring-opening processes involving conical intersections during excited state transformation between isomers. The precise location and topography of these conical intersections significantly shape the decay process and fluorescence phenomena inherent to the molecule. This work combines electronic structure theory calculations using the density functional theory and wavefunction methods, as well as surface hopping simulation to analyze the photochemical behavior of an experimentally synthesized fulgide molecule, (E)-p-methylacetophenylisopropylidenesuccinic anhydride (1E). Our study reveals the conical intersection between the first excited state (S1) and the ground electronic state (S0), which emerges beyond the S1 minimum of 1E to the ring-closing side. The distinctive topography of this conical intersection appears to be sloped. These findings suggest a reduced quantum yield for the formation of the closed isomer, indicating a higher likelihood of reformation of the open isomer(s). The surface hopping simulation further supports this observation, revealing a mere ∼8% quantum yield for the formation of the closed isomer. In addition, the photoisomerization of the fulgide molecule initiates a cascade of conduction switching and holds great potential for applications in molecular electronics. Delving into the realm of molecular electronics, we have further examined the electron transport properties, disclosing the higher conductivity of the closed isomer. [ABSTRACT FROM AUTHOR]

QM/MM methods have been used to study electronic structure properties and chemical reactivity in complex molecular systems where direct electronic structure calculations are not feasible. In our previous work, we showed that non-polarizable force fields, by design, describe intermolecular interactions through pairwise interactions, overlooking many-body interactions involving three or more particles. In contrast, polarizable force fields account partially for many-body effects through polarization, but still handle van der Waals and permanent electrostatic interactions pairwise. We showed that despite those limitations, polarizable and non-polarizable force fields can reproduce relative cooperativity achieved using density functional theory due to error compensation mechanisms. In this contribution, we assess the performance of QM/MM methods in reproducing these phenomena. Our study highlights the significance of the QM region size and force field choice in QM/MM calculations, emphasizing the importance of parameter validation to obtain accurate interaction energy predictions. [ABSTRACT FROM AUTHOR]

Refractory high-entropy alloys are under consideration for applications where materials are subjected to high temperatures and levels of radiation, such as in the fusion power sector. However, at present, their scope is limited because they are highly brittle at room temperature. One suggested route to mitigate this issue is by alloying with Ti. In this theoretical study, using a computationally efficient linear-response theory based on density functional theory calculations of the electronic structure of the disordered alloys, we study the nature of atomic short-range order in these multi-component materials, as well as assessing their overall phase stability. Our analysis enables direct inference of phase transitions in addition to the extraction of an atomistic, pairwise model of the internal energy of an alloy suitable for study via, e.g., Monte Carlo simulations. Once Ti is added into either the NbMoTaW or VNbMoTaW system, we find that there is competition between chemical phase ordering and segregation. These results shed light on observed chemical inhomogeneity in experimental samples, as well as providing fundamental insight into the physics of these complex systems. [ABSTRACT FROM AUTHOR]

To address the challenge of performance portability and facilitate the implementation of electronic structure solvers, we developed the basic matrix library (BML) and Parallel, Rapid O(N), and Graph-based Recursive Electronic Structure Solver (PROGRESS) library. The BML implements linear algebra operations necessary for electronic structure kernels using a unified user interface for various matrix formats (dense and sparse) and architectures (CPUs and GPUs). Focusing on density functional theory and tight-binding models, PROGRESS implements several solvers for computing the single-particle density matrix and relies on BML. In this paper, we describe the general strategies used for these implementations on various computer architectures, using OpenMP target functionalities on GPUs, in conjunction with third-party libraries to handle performance critical numerical kernels. We demonstrate the portability of this approach and its performance in benchmark problems. [ABSTRACT FROM AUTHOR]

A layered sodium-ion battery cathode, O3/P3/P2-type NaNi1/3Mn1/3Fe1/3O2, has been systematically investigated by first-principles density functional theory to explore the detailed structural and Na-ion diffusion behavior during desodiation. Our results suggest that the (NaO6) spacing is greatest in the P3 phase and lowest in the O3 phase, with the P2 phase exhibiting intermediate spacing. During desodiation, the intermediate stages have a greater (NaO6) spacing than the initial and final stages. The great (NaO6) spacing facilitates the formation of the P3 phase, resulting in the structural evolution of NaxNi1/3Mn1/3Fe1/3O2 from the O3 to the P3 phase at x ≈ 0.59, finally reaching the O3 structure again at x ≈ 0.12. The electronic structure clearly proves that both Ni and Fe are active in O3/P3/P2-type NaxNi1/3Mn1/3Fe1/3O2. Ni2+ is oxidized to Ni3+ as Na content decreases from x = 1 to x = 0.66, then further oxidized to Ni4+ at x = 0.33, and finally, Fe3+ → Fe4+ oxidation occurs at x = 0. In the Na ion diffusion behavior, the order of the barrier is O3 (0.82 eV) > P2 (0.53 eV) > P3 (0.35 eV) at the initial stage, whereas it is O3 (0.53 eV) > P3 (0.21 eV) > P2 (0.16 eV) at a highly desodiated stage. The former can be traced back to the (NaO6) spacing, but the latter is related to the different Na sites. Our results thus provide a factor of the structural evolution and Na ion diffusion barrier by considering (NaO6) width and Na site changes during desodiation. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising energy carrier, but its onboard application is limited by the need for compact, low-pressure storage solutions. Solid-state complex metal hydride systems, such as MgB 2 /Mg(BH 4) 2 , offer high storage capacities but suffer from sluggish kinetics and poor reversibility. One avenue for improving reactivity is to introduce metal dopants to alter electronic and atomic properties, but the role of these chemical additives remains poorly understood, particularly for the hydrogenation reaction. In this work, we used density functional theory calculations on model MgB 2 systems to rationalize the potential role of metal dopants in destabilizing B–B bonding within the MgB 2 lattice. We carried out detailed electronic structure analyses for 28 different metal dopant adatoms to identify properties that contribute to a dopant's efficacy. Based on the simulation results, we propose that an intermediate ionic and covalent character of the bonds between adatoms and B atoms is desirable for facilitating charge redistribution, disrupting the B–B bond network, and promoting H 2 dissociation and H atom chemisorption on MgB 2. [ABSTRACT FROM AUTHOR]

Since the development of generalized gradient approximations in the 1990s, approximations based on density functional theory have dominated electronic structure theory calculations. Modern approximations can yield energy differences that are precise enough to be predictive in many instances, as validated by large- and small-scale benchmarking efforts. However, assessing the quality of densities has been the subject of far less attention, in part because reliable error measures are difficult to define. To this end, this work introduces the mean-field error, which directly assesses the quality of densities from approximations. The mean-field error is contextualized within existing frameworks of density functional error analysis and understanding and shown to be part of the density-driven error. It is demonstrated in several illustrative examples. Its potential use in future benchmarking protocols is discussed, and some conclusions are drawn. [ABSTRACT FROM AUTHOR]

Since the form of the exact functional in density functional theory is unknown, we must rely on density functional approximations (DFAs). In the past, very promising results have been reported by combining semi-local DFAs with exact, i.e. Hartree–Fock, exchange. However, the spin-state energy ordering and the predictions of global minima structures are particularly sensitive to the choice of the hybrid functional and to the amount of exact exchange. This has been already qualitatively described for single conformations, reactions, and a limited number of conformations. Here, we have analyzed the mixing of exact exchange in exchange functionals for a set of several hundred isomers of the transition metal carbide, Mo4C2. The analysis of the calculated energies and charges using PBE0-type functional with varying amounts of exact exchange yields the following insights: (1) The sensitivity of spin-energy splitting is strongly correlated with the amount of exact exchange mixing. (2) Spin contamination is exacerbated when correlation is omitted from the exchange-correlation functional. (3) There is not one ideal value for the exact exchange mixing which can be used to parametrize or choose among the functionals. Calculated energies and electronic structures are influenced by exact exchange at a different magnitude within a given distribution; therefore, to extend the application range of hybrid functionals to the full periodic table the spin-energy splitting energies should be investigated. [ABSTRACT FROM AUTHOR]

Since the form of the exact functional in density functional theory is unknown, we must rely on density functional approximations (DFAs). In the past, very promising results have been reported by combining semi-local DFAs with exact, i.e. Hartree–Fock, exchange. However, the spin-state energy ordering and the predictions of global minima structures are particularly sensitive to the choice of the hybrid functional and to the amount of exact exchange. This has been already qualitatively described for single conformations, reactions, and a limited number of conformations. Here, we have analyzed the mixing of exact exchange in exchange functionals for a set of several hundred isomers of the transition metal carbide, Mo4C2. The analysis of the calculated energies and charges using PBE0-type functional with varying amounts of exact exchange yields the following insights: (1) The sensitivity of spin-energy splitting is strongly correlated with the amount of exact exchange mixing. (2) Spin contamination is exacerbated when correlation is omitted from the exchange-correlation functional. (3) There is not one ideal value for the exact exchange mixing which can be used to parametrize or choose among the functionals. Calculated energies and electronic structures are influenced by exact exchange at a different magnitude within a given distribution; therefore, to extend the application range of hybrid functionals to the full periodic table the spin-energy splitting energies should be investigated. [ABSTRACT FROM AUTHOR]

The Pauli kinetic energy functional and its functional derivative, termed Pauli potential, play a crucial role in the successful implementation of orbital-free density functional theory for electronic structure calculations. However, the exact forms of these two quantities are not known. Therefore, perforce, one employs the approximate forms for the Pauli functional or Pauli potential for performing orbital-free density functional calculations. In the present study, we developed a feed-forward neural network-based representation for the Pauli potential using a 1-dimensional (1-D) model system. We expanded density in terms of basis functions, and the coefficients of the expansion were used as input to a feed-forward neural network. Using the neural network-based representation of the Pauli potential, we calculated the ground-state densities of the 1-D model system by solving the Euler equation. We calculated the Pauli kinetic energy using the neural network-based Pauli potential employing the exact relation between the Pauli kinetic energy functional and the potential. The sum of the neural network-based Pauli kinetic energy and the von Weizsäcker kinetic energy resulted in an accurate estimation of the total kinetic energy. The approach presented in this paper can be employed for the calculation of Pauli potential and Pauli kinetic energy, obviating the need for a functional derivative. The present study is an important step in the advancement of application of machine learning-based techniques toward the orbital-free density functional theory-based methods. [ABSTRACT FROM AUTHOR]

Detailed characterization of deep-level color centers requires understanding their electronic and atomic structure, which is most commonly investigated utilizing the Kohn–Sham density functional theory. Standard semilocal functionals based on the generalized gradient approximation (GGA) are inclined toward an imprecise quantitative description of defects' electronic structure. Hybrid functionals provide an improved prediction of electronic properties, albeit at a much higher computational cost. In this work, we test the newly developed Strongly Constrained and Appropriately Normed (SCAN) family of meta-GGA density functionals for selected color centers in diamond. In particular, we study nitrogen-, silicon-, germanium-, and tin-vacancy centers that have been recently investigated for their use in quantum technological applications. We show that SCAN and its derivatives, the rSCAN and r2SCAN functionals, significantly improve the calculated energies of optical transitions within the delta-self-consistent-field approach, almost reaching the accuracy of the hybrid Heyd–Scuseria–Ernzerhof (HSE) functional. In the case of the NV− center, we also show that the SCAN family of functionals improves the description of the adiabatic potential energy surfaces compared to both GGA and hybrid functionals, improving calculated luminescence lineshapes. As a result of these findings, we recommend using the SCAN family of functionals as a promising alternative for studying color centers in solids. [ABSTRACT FROM AUTHOR]

First-principles calculations for electrochemistry require accurate treatment of both electronic structure and solvation. The perturbative GW approximation starting from density functional theory (DFT) calculations accurately models materials systems with varying dimensionality. Continuum solvation models enable efficient treatment of solvation effects in DFT calculations, but their applications with beyond-DFT electronic structure methods such as GW have been limited. Here, we introduce the frequency-dependent liquid polarizability from a nonlocal continuum solvation model in the screened Coulomb interaction of full-frequency GW calculations with a solvated DFT starting point. We show that the liquid screening contributions substantially reduce the HOMO–LUMO gap of molecules by 3–5 eV, while solvent effects on the DFT starting point negligibly impact the GW gap. The resulting framework facilitates the simultaneous electronic and solvation accuracy needed for first-principles electrochemistry. [ABSTRACT FROM AUTHOR]

Coarse-grained molecular dynamics (CGMD) simulations address lengthscales and timescales that are critical to many chemical and material applications. Nevertheless, contemporary CGMD modeling is relatively bespoke and there are no black-box CGMD methodologies available that could play a comparable role in discovery applications that density functional theory plays for electronic structure. This gap might be filled by machine learning (ML)-based CGMD potentials that simplify model development, but these methods are still in their early stages and have yet to demonstrate a significant advantage over existing physics-based CGMD methods. Here, we explore the potential of Δ-learning models to leverage the advantages of these two approaches. This is implemented by using ML-based potentials to learn the difference between the target CGMD variable and the predictions of physics-based potentials. The Δ-models are benchmarked against the baseline models in reproducing on-target and off-target atomistic properties as a function of CG resolution, mapping operator, and system topology. The Δ-models outperform the reference ML-only CGMD models in nearly all scenarios. In several cases, the ML-only models manage to minimize training errors while still producing qualitatively incorrect dynamics, which is corrected by the Δ-models. Given their negligible added cost, Δ-models provide essentially free gains over their ML-only counterparts. Nevertheless, an unexpected finding is that neither the Δ-learning models nor the ML-only models significantly outperform the elementary pairwise models in reproducing atomistic properties. This fundamental failure is attributed to the relatively large irreducible force errors associated with coarse-graining that produces little benefit from using more complex potentials. [ABSTRACT FROM AUTHOR]

Recent work on atomic-precision dopant incorporation technologies has led to the creation of both boron and aluminum δ -doped layers in silicon with densities above the solid solubility limit. We use density functional theory to predict the band structure and effective mass values of such δ layers, first modeling them as ordered supercells. Structural relaxation is found to have a significant impact on the impurity band energies and effective masses of the boron layers, but not the aluminum layers. However, disorder in the δ layers is found to lead to a significant flattening of the bands in both cases. We calculate the local density of states and doping potential for these δ -doped layers, demonstrating that their influence is highly localized with spatial extents at most 4 nm. We conclude that acceptor δ -doped layers exhibit different electronic structure features dependent on both the dopant atom and spatial ordering. This suggests prospects for controlling the electronic properties of these layers if the local details of the incorporation chemistry can be fine-tuned. [ABSTRACT FROM AUTHOR]

DFT functionals are of paramount importance for an accurate electronic and structural description of transition metal systems. In this work, a systematic analysis using some well‐known and commonly used DFT functionals is performed. A comparison of the structural and energetic parameters calculated with the available experimental data is made in order to find the adequate functional for an accurate description of the TiO2 bulk and surface of both anatase and rutile structures. In the absence of experimental data on the surface energy, the theoretical predictions obtained using the high‐accuracy HSE06 functional were used as a reference to compare against the surface energy values calculated with the other DFT functionals. A clear improvement in the electronic description of both anatase and rutile was observed by introducing the Hubbard U correction term to PBE, PW91, and OptPBE functionals. The OptPBE‐U4 functional was found to offer a good compromise between accurately describing the structural and electronic properties of titania. [ABSTRACT FROM AUTHOR]

Recently, graphyne-based gas sensors have drawn a lot of interest. One kind of graphene with acetylene bonds connecting its hexagons is graphyne. In this study, the density functional theory (DFT) method was used to investigate the physical parameters of the surface adsorption of carbon monoxide on the α- and γ-graphyne nanosheet, taking into account van der Waals (vdW) interactions through the use of the SIESTA computational code. CO molecule adsorbed and optimized in two vertical and horizontal states from the side of carbon and oxygen atoms, at different distances and sites relative to the graphyne sheet. After optimization and finding the adsorption energy, the best adsorption sites, equilibrium distance of the molecule from the surface, electronic structure, charge transfer rate, and bandgap changes were calculated. It was observed that the changes in the electronic structure after the adsorption of CO molecule are insignificant and the α- and γ-graphyne nanosheets remained zero-gap and narrow-gap semiconductors, respectively. The adsorption of CO molecule on the α- and γ-graphyne nanosheets is physisorption. The results show that the γ-graphyne nanosheet has a good potential for adsorbing and detecting CO molecules and sensor applications. [ABSTRACT FROM AUTHOR]

Here, we describe a set of coupled experimental and theoretical analyses. The introduction of one and two additional cyano groups in the carboheptahelicene backbone enhance its electron‐accepting properties. New carboheptahelicene derivatives are synthesized, and relevant characterizations of structural features, photophysical and electrochemical properties, and structure‐property relationships are described. This present work concerns the use of the density functional theory (DFT) to highlight the structural and the optoelectronic properties of carboheptahelicene derivatives and comparing the obtained findings with the experimental ones. The experimental and theoretical spectra (UV‐Vis absorption and photoluminescence) provide excellent concurrence. Afterward, molecular structures, structural parameters, molecular electrostatic potential (MEP), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of frontier molecular orbitals (FMOs) are constructed. Some other optoelectronic parameter including electron affinity (EA), ionization potential (IP), and some reactive descriptor such as chemical potential (μ), global hardness (η), electronegativity (χ) and the overall electrophilicity index (ω) are determined and indicating its potential uses as an active layer in optoelectronic efficient devices. The topological methods such as electron localization function (ELF), localization orbital locator (LOL) and the reduced density gradient method (RDG) were also conducted to clarify the strengths and kinds of interactions. [ABSTRACT FROM AUTHOR]

The present work gives the structural, dehydriding and electronic characteristics of MgH 2 with Ti or/and S additives by first-principles density functional theory calculations. It is found that Ti and S prefer to occupy Mg site and interstitial site, respectively, in terms of occupation energy (E occ). Furthermore, Ti + S incorporation into MgH 2 lattice is more energetically favorable (E occ = −0.051 eV–0.944 eV) relative to single Ti incorporation (E occ = 1.314 eV–1.784 eV), for which the promotion of adequate Mg site by S addition is chiefly responsible. Ti, S, and especially Ti + S doping not only reduce the hydrogen dissociation energy from 1.619 eV/2.317 eV (Mg 16 H 32) to 0.350 eV/0.967 eV (Mg 15 TiSH 32) for H-atom/H-molecule desorption, but also decrease the hydrogen diffusion energy barrier from 0.706 eV/0.704 eV (Mg 16 H 32) to 0.342 eV/0.169 eV (Mg 15 TiSH 32) along path I/II, respectively. As a result, a significant improvement on the thermodynamical and kinetical performance of MgH 2 can be achieved using Ti or/and S. This improvement is attributed to the higher electronegativity of Ti (relative to Mg), the decrease of Mg–H interaction and the formation of Ti–H and Mg–S bonds. Our studies provide new insight into the enhanced dehydrogenation of MgH 2 modified by Ti and S, which is useful for designing advanced magnesium hydrides with favorable H-desorption performance. • Enhanced dehydrogenation of MgH 2 with Ti or/and S additives is investigated theoretically. • Ti, S and especially Ti + S effectively modify the thermodynamics and kinetics of MgH 2. • Decrease of Mg–H interaction leads to destabilized MgH 2 for favorable H-desorption. • Formation of Ti–H and Mg–S bonds in Ti or/and S doped MgH 2 favors for H-desorption. [ABSTRACT FROM AUTHOR]

Chemical and topological short-range ordering are important for glass formation in metallic alloys. Yet, it remains little understood from the viewpoint of the electronic bonding among the constituent elements of the alloys. In this work, we study CuxZr100−x, (46 ≤ x ≤ 70) metallic glasses, where the atomic packing efficiency and the electronic structure of the full icosahedra, the key short-range order structures, have been investigated in detail. To capture a realistic picture of the electronic bonding in the icosahedra in the as-quenched metastable state, DFT study of the electronic structure of the icosahedra extracted from classical molecular dynamics simulation is carried out. Results for the CunZr13−n, (4 ≤ n ≤ 9) clusters reveal that Cu6Zr7, Cu7Zr6 and Cu8Zr5 are the most abundant, electronically stable in Cu50Zr50, Cu58Zr42 and Cu64Zr36, respectively. These three clusters also exhibit pseudo-gap in the density of states at the Fermi level – a feature linked with glass-forming ability according to the nearly-free electron approach. The partial density of states demonstrates the effect of small changes in the stoichiometry of the clusters on the s, p and d states of Cu and Zr in Cu–Cu and Cu–Zr bonding and hence, the stability of the clusters. [ABSTRACT FROM AUTHOR]

Herein, we successfully synthesized a copper nanocluster, [Cu58(SeC6H5)24(Dppe)6Se16]2+. The Cu58 features a tetrahedral Cu4 core, surrounded by tetrahedral Se4 and octahedral Cu6 subunits, and further stabilized by Cu3Se3, Cu3(SeR)3, and DppeCu2 staples, which can be interpreted as an assembly of tetrahedral and octahedral units. Density functional theory (DFT) calculations were employed to investigate the electronic structure of Cu58. This nanocluster demonstrates excellent catalytic properties in copper-catalyzed [3+2] azide–alkyne cycloaddition (CuAAC) reactions. Additionally, Cu58 enriches the structural diversity of copper-based nanoclusters, providing valuable insights for future structural predictions. [ABSTRACT FROM AUTHOR]

In this work, the effects of magnetic proximity coupling on electronic structures, valley polarization and magneto-crystal anisotropy of VI3/WSe2 heterostructure are studied in detail based on density functional theory. The results show that the spin-valley polarization characters of WSe2 monolayer can be induced by the proximity effect of ferromagnetic VI3 monolayer. Based on the effective Hamiltonian k ⋅ p model, a large valley polarization of 8.7 meV is observed, which is mainly contributed by the SOC effect and not magnetic exchange field. Meanwhile, the magneto-crystal anisotropy of VI3 layer is also obviously altered from the [100] to [001] magnetic axis compared to the isolated VI3 monolayer. The reduction in the interlayer space strengths the W–V atomic coupling, resulting in a significant increase in the spin and valley polarization. Compression strain shows weakening effect on the valley polarization, while the tensile strain largely enhances the valley polarization of VI3/WSe2 heterostructure, which can reach the maximum value of 29.1 meV at the tensile strain of 8%. The V spin direction (θ) has significant effect on valley polarization of WSe2 layer, which is positively correlated with the magnetization strength of V atom in the vertical direction. Furthermore, constructing the VI3/WSe2/VI3 sandwich heterostructure can induce a larger valley polarization, which can reach a maximum value of 32.4 meV. These results indicate that the VI3/WSe2 heterostructure is a potential candidate for valleytronics. [ABSTRACT FROM AUTHOR]

MXenes exhibit unique structural flexibility, excellent carrier mobility and abundant active sites, making them valuable catalysts in photocatalysis. The electronic properties and photocatalytic activity of Janus ZrMCO 2 (M = Ti, Hf) MXenes are investigated by hybrid HSE06 functional. Photocatalytic activities of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are further explored. Structural stability is proved by negative cohesive energy and elastic stiffness coefficients. ZrTiCO 2 and ZrHfCO 2 are all direct semiconductors. Ti/Hf doping makes conduction band minimum (CBM) have a redshift and induces the reduction of band gaps of Janus systems. The three systems are potential photocatalysts due to their appropriate bandgaps and significant absorption in visible region. The irradiation-generated holes and electrons can easily drive the HER or OER on ZrHfCO 2 MXene due to the small overpotential. ZrHfCO 2 and Zr 2 CO 2 are highly efficient for photocatalytic hydrogen production with STH efficient of 30.3%. Hf doping improves the photocatalytic reduction of CO 2 , while The Ti/Hf doping doesn't improve the N 2 reduction. • Ti/Hf doping induces the reduction of band gaps of Janus systems. • ZrHfCO 2 and Zr 2 CO 2 are highly efficient for photocatalytic hydrogen production with STH efficient of 30.3%. • ZrHfCO 2 and Zr 2 CO 2 can perform complete PWS reactions in acidic solution. • Hf doping can reduce the overpotential for OER and HER of Zr 2 CO 2. [ABSTRACT FROM AUTHOR]

Highly dispersed Pd/N-doped carbon dots (Pd/NCDs) were successfully immobilized in the mesoporous channels of amino-functionalized dendritic mesoporous silica nanospheres (NMS). The synthesized Pd/NCDs@NMS catalyst exhibits outstanding performance in the catalytic reduction of 4-nitrophenol (4-NP), achieving a turnover frequency of 1461.8 mol·molPd−1·h−1, with the conversion rate remaining above 80% after 11 cycles. Experiments and density functional theory calculations reveal that the NCDs significantly affect the electronic structure of Pd nanoparticles, leading to changes in the energy barriers for the adsorption of 4-NP at the Pd sites and the conversion of 4-NP reaction intermediates, which is a key factor contributing to the catalytic performance. This study offers a new strategy for synthesizing carbon-dot-modified metal-based catalysts. [ABSTRACT FROM AUTHOR]

The catalytic efficiency of CeO2 in soot oxidation was significantly affected by its grain morphology and calcination temperature. Nanocube-shaped and nanorod-shaped CeO2 catalysts were synthesized via a hydrothermal method with different calcination temperatures. Activity tests revealed that the nanorod-shaped CeO2 exhibited superior catalytic activity compared to the nanocube-shaped catalysts at equivalent calcination temperatures. Furthermore, an inverse relationship between the catalytic activity and the calcination temperature was observed in the nanorod-shaped CeO2 catalysts, with those calcined at 300 °C exhibiting the most effective low-temperature catalytic performance. Combined characterization techniques and density functional theory calculations showed that the improved catalytic performance can be attributed to the increased abundance of oxygen vacancies, enhanced lattice oxygen mobility and higher surface energy due to their unique surface defect structure and electronic structural feature, in addition to the reduction in grain size. [ABSTRACT FROM AUTHOR]

The modulation of electronic structure plays a crucial role in enhancing the adsorption of H* for photocatalytic hydrogen evolution. In this study, we prepared a three-dimensionally ordered macroporous structure of cobalt doping SrTiO 3 (Co/3DOMSTO) to provide a large specific surface area that exposes more active sites. The prepared catalysts exhibited the highest rate of photocatalytic hydrogen evolution, reaching 5892.86 μmol g−1 h−1, along with an apparent quantum efficiency (AQE) of approximately 2.4% under illumination at 427 nm. Additionally, the introduction of metal cobalt helped to modulate the electronic structure of Co/3DOMSTO and facilitate spatial charge separation. X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations were conducted to demonstrate that cobalt occupied the Ti sites on the surface of 3DOMSTO, resulting in changes in the electronic distribution state within space. This phenomenon facilitates the enrichment of electrons at the adjacent Ti sites, making the charge-rich Ti a new active site. These findings underscore the pivotal role played by the geometric configuration and tailored electronic structure of 3DOMSTO in augmenting its photocatalytic performance. [Display omitted] • Successfully prepared Cobalt-doping SrTiO 3 with 3D macroporous structure. • The hydrogen evolution rate of Co/3DOMSTO-45 increased by approximately ten-fold. • The enhanced photocatalytic activity is attributed to the activation of titanium atoms. [ABSTRACT FROM AUTHOR]

van der Waals (vdWs) interchain coupling is a unique feature of 1D vdWs materials, where strong vdWs coupling in 1D vdWs materials leads to the thickness‐dependent physical properties, while weak vdWs coupling can preserve the single‐chain property even in their thick counterparts. Different from 2D vdWs materials, due to their nanoscale widths, identifying and producing ultrathin 1D molecular chains are challenging, severely limit their device applications. Thus, looking for novel 1D vdWs materials with weak interchain coupling is crucial. In this paper, the authors report that the 1D ternary vdWs material, Mo6Se2I8 with non‐centrosymmetric characteristic and strong optical anisotropy, exhibits weak interchain coupling. On one hand, the density functional theory (DFT) calculations theoretically demonstrate its thickness‐independent electronic structure, negligible interchain differential charge density, and weak cleavage energy as low as 0.256 J m−2. On the other hand, the thickness‐independent work function and low first‐order temperature coefficient of −0.0030 cm−1 K−1 further experimentally confirm its weak interchain coupling. Moreover, taking advantage of this weak vdWs coupling characteristic, the in situ exfoliation of the Mo6Se2I8 nanowires is achieved by using a nanoprobe in a scanning electron microscope (SEM), obtaining ultrathin molecular chains with a thickness of ≈1.2 nm. [ABSTRACT FROM AUTHOR]

Tuning the lattice strain of catalysts represents a powerful strategy to alter their electronic structures and ultimately regulate catalytic performance. Electrocatalytic CO2 reduction is a promising avenue to accomplish the carbon‐neutral cycle, however, there still lacks a distinct and systematic understanding of the lattice strain effect in CO2 electrochemical conversion. In this work, the influence of lattice strain on Bi (012) facets to formate production is studied. The pre‐executed density functional theory (DFT) calculations reveal that lattice compression promotes the wrinkling of exposed Bi surface and increases the total density of state (DOS) of active sites at the Fermi level. As the gradual intensification of lattice contraction, the selectivity of CO2 reduction exhibits a volcanic alteration, with an optimal lattice contraction of 3%. Experimentally synthesized Bi2O2CO3/Bi heterogeneous catalyst confirms the effect of lattice compression. When compression reaches −3.04% on Bi (012) facets, the catalyst possesses the highest Faraday efficiency (FE) of 96.17% at −1.2 VRHE and an industrially scalable current density of −600 mA cm−2. Additionally, in seawater‐based electrolysis, the catalyst also exhibits excellent remarkable FE of 95.43% of formate production. [ABSTRACT FROM AUTHOR]

Edge state and interfacial design are efficient strategies to regulate the spin-transport properties of nanoscale devices. Spin-polarized transport properties of VC2 nanoribbon device and poly-(terphenylene-butadiynylene) PTB molecular junctions are studied by using density functional theory (DFT) and non-equilibrium Green function. Results show good self-selected filtering properties for spin-up current are highly suppressed, where there is only spin-down current that can propagate through the scattering region of such a nanoribbon device. What needs to be pointed out is that spin-down current exhibits an obvious negative differential resistance effect. Current and transmission spectrum peaks are significantly weakened, and the negative differential resistance effect disappears after a PTB molecule is embedded between two semi-infinite VC2 nanoribbon electrodes. This work provides a basis for improving the design and method of spintronic devices. [ABSTRACT FROM AUTHOR]

The ground state electron density — obtainable using Kohn-Sham Density Functional Theory (KS-DFT) simulations — contains a wealth of material information, making its prediction via machine learning (ML) models attractive. However, the computational expense of KS-DFT scales cubically with system size which tends to stymie training data generation, making it difficult to develop quantifiably accurate ML models that are applicable across many scales and system configurations. Here, we address this fundamental challenge by employing transfer learning to leverage the multi-scale nature of the training data, while comprehensively sampling system configurations using thermalization. Our ML models are less reliant on heuristics, and being based on Bayesian neural networks, enable uncertainty quantification. We show that our models incur significantly lower data generation costs while allowing confident — and when verifiable, accurate — predictions for a wide variety of bulk systems well beyond training, including systems with defects, different alloy compositions, and at multi-million-atom scales. Moreover, such predictions can be carried out using only modest computational resources. [ABSTRACT FROM AUTHOR]

Fine control over the graphitization level of carbonized nanostructures can play a strategic role in tuning the crystallization of supported nanocatalysts, thereby modulating the kinetics of catalysis. However, realizing the synergistic interplay of graphitization‐tunable support and supported catalysts poses a significant challenge. This study proposes a current pulse‐induced ultrafast strategy for developing MOF‐derived graphitic nano‐leaves (GNL) and supported ultrafine ruthenium nanoclusters exhibiting selective crystallization states depending on the tunable graphitization level of GNL. The resulting ultrafine (≈0.7 nm) amorphous‐ruthenium nanoclusters linked with GNL (a‐Ru@GNL500) exhibit state‐of‐the‐art performance in the hydrogen evolution reaction (HER), requiring very low overpotentials of only 23.0 and 285.0 mV to achieve current densities of 10 and 500 mA cm−2, respectively. Furthermore, a‐Ru@GNL500 demonstrates exceptional operational stability for 100 h under high HER currents of 200 and 400 mA cm−2. Density functional theory reveals that the unique electronic structure of a‐Ru and the cooperative effect of cobalt embedded in the graphitic layer lower the occupancy of the antibonding orbital, resulting in an accelerated HER process. Additionally, the unique electronic structure, highly conducting GNL, and efficient bubble release dynamics of super‐aerophobic a‐Ru@GNL500 contribute to reduced overpotentials, particularly at high HER current densities. [ABSTRACT FROM AUTHOR]

The electronic structure of silicene supported by monolayer of different monochalcogenide MX (GaS, GaSe, GaTe and InSe) substrates has been investigated by first principle density functional theory. By calculating the formation energies and phonons, it has been seen that silicene supported by monolayer of MX remains stable. The systems retain their almost 2 D planner configurations with small buckling as that of the free standing silicene and also the Bader charge analysis shows that silicene hardly interacts with any of the MX substrates. The Dirac cone with a small gap (∼ 3 0 – 5 0   meV) has been observed in each of the cases. All the systems show quantum spin Hall effect and the quantum spin Hall conductivities have been estimated to be within the range ∼ 2 − 5 ℏ e S/cm, which are larger than that of the free standing silicene. Our calculations show that even if the systems have bulk band gaps but the edge states are conducting in nature. [ABSTRACT FROM AUTHOR]

In this work, the first‐principles study based on density functional theory was applied to investigate the geometries, electronic structures, and optical properties in four directions of the Si‐NWs surface, which are modified by oxygen atoms. The results show that the geometries, band structures, and optical properties of the Si‐NWs are affected by the modification of oxygen atoms. The Si─Si bonds adjacent to the region modified by oxygen atoms elongate, the cell volumes decrease, while the energy gaps of Si‐NWs narrow. Evident impurity bands appear on the energy bands of the modified Si‐NWs, forming S═O double bonds. A blue shift of the perpendicular component spectra of the dielectric constant relative to parallel spectra can be observed for Si [100]‐NW, Si [111]‐NW, and Si [112]‐NW. At the same time, the real and imaginary parts of the dielectric function spectra of all Si‐NWs are red‐shifted after the modification by oxygen atoms, and the spectra of Si [111]‐NWs forming Si═O double bonds are the most significant red‐shifted. These results can provide a theoretical reference for preparing nano‐silicon optoelectronic materials and devices. [ABSTRACT FROM AUTHOR]

Density functional theory calculations have been performed to compare the HCHO decomposition on Co3O4(110)-A and (110)-B terminations. The results showed that the energy barriers of the two C–H bond cleavages of HCHO on the (110)-A termination were lower than those on the (110)-B termination, suggesting that the (110)-A termination had stronger HCHO decomposition ability than the (110)-B termination. Electronic structures revealed that the stronger HCHO decomposition ability of the (110)-A termination might be ascribed to the strong covalent bond between HCHO and the (110)-A termination, as well as the higher d-band center of Co3+ ions on the (110)-A termination. Furthermore, we proposed that the preparation of Co3O4 under oxygen-rich growth conditions was beneficial to HCHO decomposition because the (110)-A termination was more stable under oxygen-rich conditions. [ABSTRACT FROM AUTHOR]

The practical application of the electrocatalytic CO2 reduction reaction (CO2RR) to form formic acid fuel is hindered by the limited activation of CO2 molecules and the lack of universal feasibility across different pH levels. Herein, we report a doping‐engineered bismuth sulfide pre‐catalyst (BiS‐1) that S is partially retained after electrochemical reconstruction into metallic Bi for CO2RR to formate/formic acid with ultrahigh performance across a wide pH range. The best BiS‐1 maintains a Faraday efficiency (FE) of ~95 % at 2000 mA cm−2 in a flow cell under neutral and alkaline solutions. Furthermore, the BiS‐1 catalyst shows unprecedentedly high FE (~95 %) with current densities from 100 to 1300 mA cm−2 under acidic solutions. Notably, the current density can reach 700 mA cm−2 while maintaining a FE of above 90 % in a membrane electrode assembly electrolyzer and operate stably for 150 h at 200 mA cm−2. In situ spectra and density functional theory calculations reveals that the S doping modulates the electronic structure of Bi and effectively promotes the formation of the HCOO* intermediate for formate/formic acid generation. This work develops the efficient and stable electrocatalysts for sustainable formate/formic acid production. [ABSTRACT FROM AUTHOR]

Machine learning techniques have found their way into computational chemistry as indispensable tools to accelerate atomistic simulations and materials design. In addition, machine learning approaches hold the potential to boost the predictive power of computationally efficient electronic structure methods, such as density functional theory, to chemical accuracy and to correct for fundamental errors in density functional approaches. Here, recent progress in applying machine learning to improve the accuracy of density functional and related approximations is reviewed. Promises and challenges in devising machine learning models transferable between different chemistries and materials classes are discussed with the help of examples applying promising models to systems far outside their training sets. [ABSTRACT FROM AUTHOR]

Nano‐single‐atom‐catalysts have the potential to combine the respective advantages of both nano‐catalysts and single‐atom‐catalysts and thus exhibit enhanced performance. Generally, the separation of active sites in space limits the interaction between single atoms and nanoparticles. Heterointerface engineering has the potential to break this limitation. Regretfully, studies on the interface effect between single atoms and nanoparticles are rarely reported. Herein, an unprecedented nano‐single‐atom heterointerface composed of Fe single‐atoms and carbon‐shell‐coated FeP nanoparticles (Fe SAC/FeP@C) is demonstrated as an efficient electrocatalyst for the nitrate reduction process from alkaline to acidic. Compared with typical nano‐single‐atom‐catalysts (Fe SAC/FePO4) and single‐atom‐catalysts (Fe SAC), the constructed Fe SAC/FeP@C heterostructure exhibits dramatically enhanced nitrate‐to‐ammonia performance. Especially in acidic media, the maxmium Faradaic efficiency of ammonia (NH3) can reach 95.6 ± 0.5%, with a maximum NH3 yield of 36.2 ± 3.1 mg h−1 mgcat−1 (pH = 1.2), which is considerably higher than previously reported. Density functional theory calculations and in situ spectroscopic investigations indicate that the unique charge redistribution at the interface, together with the optimized electronic structure of Fe single‐atoms, strengthens intermediate adsorption and catalytic activity. This work provides a feasible strategy for designing nano‐single‐atom‐catalysts with unique heterointerfaces, as well as valuable insights into nitrate conversion under environmentally relevant wastewater conditions. [ABSTRACT FROM AUTHOR]

Despite the extensive applications of perovskite compounds, the precise nature of non‐Hermitian bonding in these materials remains poorly understood. In this study, density functional theory calculations are performed to determine the electronic structures of perovskite compounds. In particular, the bandgaps of Ba2ScNbO6 and Ba2LuNbO6 are found to be 2.617 and 2.629 eV, respectively, and the deformation bond energies and non‐Hermitian bonding of these compounds are calculated. The relationship between the non‐Hermitian zeros of the O‐Nb bond of Ba2ScNbO6 and the non‐Hermitian zeros of the Sc‐O bond is found to be similar but with varying sizes. Further, in‐depth research on non‐Hermitian chemistry verified that precise control of atomic bonding and electron states can be achieved, providing new insights into the study of chemical bonds. [ABSTRACT FROM AUTHOR]

Exploring highly active electrocatalysts as platinum (Pt) substitutes for the oxygen reduction reaction (ORR) remains a significant challenge. In this work, single Mn embedded nitrogen-doped graphene (MnN4) with and without halogen ligands (F, Cl, Br, and I) modifying were systematically investigated by density functional theory (DFT) calculations. The calculated results indicated that these ligands can transform the dyz and dxz orbitals of Mn atom in MnN4 near the Fermi-level into d z 2 orbital, and shift the d-band center away from the Fermi-level to reduce the adsorption capacity for reaction intermediates, thus enhancing the ORR catalytic activity of MnN4. Notably, Br and I modified MnN4 respectively with the lowest overpotentials of 0.41 and 0.39 V, possess superior ORR catalytic activity. This work is helpful for comprehensively understanding the ligand modification mechanism of single-atom catalysts and develops highly active ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

Context and results : In this paper, the crystal structure, electronic, optical, and mechanical properties of SrVO3 have been systematically studied by first-principles calculation. The results show that the calculated lattice parameters are in good agreement with the experimental values of X-ray diffraction. The density of states is described in detail in this paper. By analyzing the crystal structure and electronic properties of SrVO3, the magnetic properties of SrVO3 are obtained from the one unpaired electrons of V and the exchange interaction between two V ions. At the same time, a detailed analysis of the optical properties of SrVO3 was conducted, and it was found that it is transparent in the visible light range. Finally, the mechanical properties of SrVO3 are calculated, which can provide some references for future research. Computational method: In this paper, a first-principles method based on density functional theory (DFT) is reported for PBE-GGA analysis using the plane wave-pseudo potential method in a quantum concentrate packet, U value of 7 eV to V-d and a U value of 2 eV to O-p, Grimme correction by DFT-D method. The k points in the Brillouin region are set to 4 × 4 × 4. The energy convergence criterion for self-consistent field calculation is set at 5.0 × 10−6 eV/atom, and the cutoff energy is 1170 eV. In this paper, the force acting on each atom is not more than 0.01 eV/Å, the maximum stress is not more than 0.02GPa, and the maximum atomic displacement is 5 × 10−4 Å. [ABSTRACT FROM AUTHOR]

Context : Phographene and its family member structures are of the newly proposed semiconductors for detection of chemicals. That is, in this project, the potential of using α-phographene (α-POG) both for adsorption and detection of five types of the most important air pollutant gases containing SO2, AsH3, CF3H, NO2, and CO2 species were investigated. The results of the time dependent density functional theory (TD-DFT) calculations indicate that during the adsorption of NO2, and SO2 by the sorbent, big redshifts occur (up to 866.2 nm, and 936.5, respectively) resulting in considerable changes in the orbitals and the electronic structures of the systems. Moreover, the results of the thermodynamic calculations reveal that α-POG could selectively adsorb SO2, NO2, and AsH3 gases (with different orders), but it could not adsorb the two other gases.Finally, the outcome of the band gap calculations shows that between all mentioned gases, α-POG could selectively detect the presence of SO2, and then NO2; while, this nanosheet could not sense the existence of AsH3, CF3H, or CO2 gases. Methods: All of the calculations were carried out by using the Gaussian 03 quantum chemical package. In addition, the physiochemical parameters were extracted from the output files for further calculations. Studies on all saddle points and the following calculations were performed applying the B3LYP/6-311g(d,p) level of theory. [ABSTRACT FROM AUTHOR]

Context: Density functional theory (DFT) calculations on the ground and the first excited state are performed on the modified and unmodified 4-(methoxyphenyl acetonitrile) monomer (referred to as MPA). The modified monomer named MFA is obtained by Knoevenagel condensation of MPA with dimethylformamide dimethyl acetal (DMF-DMA). DFT computations show that the chemical grafting of the dimethylamino group onto the MPA unit induces a great change in the geometric, electronic, and optical properties. Going from MPA to MFA monomer, a great change in the frontier orbitals of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the ground and the first excited state is observed. Consequently, a reduction in the energy gap HOMO–LUMO and an enhancement in the absorption and emission properties are observed under the chemical modification. The observed modifications in the electronics and optical properties are the result of the charge transfer appearing between the cyano (C≡N) acceptor group and the dimethylamino (DMF-DMA)-grafted group donor ring. Methods: Quantum chemical calculations were performed in the ground and the first excited state using the density functional theory (DFT), and it extends the time-dependent density functional theory (TD-DFT), implemented in the Gaussian 09 software package. The ground state is obtained by optimization of the studied molecular geometries by employing the DFT/M062X/6-31G(d,p) level of theory. The first excited state is obtained by re-optimization of the ground state geometries using the TD-DFT/M062X/6-31G(d,p) level of theory. The contour plots of the frontier orbitals and the molecular electrostatic potential (MEP) maps are obtained from the ground and the first excited state, optimized geometries, and drawn using Gaussview software. [ABSTRACT FROM AUTHOR]