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This study presents Born–Oppenheimer energies and transition dipole moments of the 36 lowest electronic states of the N 2 + ion as a function of internuclear distance in the interval between 1.5 and 10 bohrs obtained in first-principles calculations. The electronic states are of the total electronic spin S = 1/2, 3/2, and 5/2, dissociating toward to the lowest four N(4S0) + N+(3P), N(2P0) + N+(3P), N(2D0) + N+(3P), and N(4S0) + N+(1D) dissociation limits. Energies of the lowest states, dissociating toward to the N(4S0) + N+(3P) limit, are computed accounting for relativistic corrections. The obtained potential energy curves and the transition dipole moments are employed to compute vibrational energies in these states, vibronic transition dipole moments, and the Einstein coefficients for radiative transitions between the vibronic levels. [ABSTRACT FROM AUTHOR]

The charge-transfer energy contribution is one of the most controversial components of the total interaction energy. Commonly, the energy associate to a charge-transfer process depends on population analysis. Therefore, the results further depend on how the population analysis is defined, and certainly, the results may be arbitrary. Moreover, another important feature of the current methods is the basis sets dependency. The results of methodologies that depend on orbital-based population analyses tend to have a strong dependency on the size of the basis set utilized. This basis set dependency is eliminated by using spatial partitioning population analyses. However, these methodologies still rely on the arbitrary choice of how to divide the space. In this work, we study the use of the molecular dipole moment as a reference to describe the charge transfer-free system, i.e., a system in which the charge-transfer process is avoided. We use the recently developed constrained dipole moment density functional theory methodology to constrain the dipole moment of several systems according to reference values. These dipole moment references do not present charge transfer nor polarization contributions. In this manner, we have calculated the charge-transfer energy contributions and the total interaction energies of 13 non-covalent complexes. In addition, we determined two long range charge-transfer excitations considering the dipole moment as a reference. The calculated charge-transfer energy contributions and excitation energies are in a very good agreement with the fragment-based Hirshfeld methodology. Nevertheless, the constrained dipole moments results do not depend on population analysis. Moreover, the method is robust with respect to the strength of the charge transfer and the basis set size. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are crucial for understanding the structural and dynamical behavior of biomolecular systems, including the impact of their environment. However, there is a gap between the time scale of these simulations and that of real-world experiments. To address this problem, various enhanced simulation methods have been developed. In addition, there has been a significant advancement of the force fields used for simulations associated with the explicit treatment of electronic polarizability. In this study, we apply oscillating chemical potential grand canonical Monte Carlo and machine learning methods to determine reaction coordinates combined with metadynamics simulations to explore the role of Mg2+ distribution and electronic polarizability in the context of the classical Drude oscillator polarizable force field on the stability of the twister ribozyme. The introduction of electronic polarizability along with the details of the distribution of Mg2+ significantly stabilizes the simulations with respect to sampling the crystallographic conformation. The introduction of electronic polarizability leads to increased stability over that obtained with the additive CHARMM36 FF reported in a previous study, allowing for a distribution of a wider range of ions to stabilize twister. Specific interactions contributing to stabilization are identified, including both those observed in the crystal structures and additional experimentally unobserved interactions. Interactions of Mg2+ with the bases are indicated to make important contributions to stabilization. Notably, the presence of specific interactions between the Mg2+ ions and bases or the non-bridging phosphate oxygens (NBPOs) leads to enhanced dipole moments of all three moieties. Mg2+–NBPO interactions led to enhanced dipoles of the phosphates but, interestingly, not in all the participating ions. The present results further indicate the importance of electronic polarizability in stabilizing RNA in molecular simulations and the complicated nature of the relationship of Mg2+–RNA interactions with the polarization response of the bases and phosphates. [ABSTRACT FROM AUTHOR]

The dielectric function of a dipolar liquid exhibits a strong wavenumber dependence in the bulk homogeneous state. Such a behavior seems to suggest the possibility of a strong system size dependence of the dielectric constant (DC) of a nanoconfined liquid, although details have been revealed only recently. The dielectric properties of nanoconfined water, indeed, show a marked sensitivity not only to the size and shape (dielectric boundaries) of confinement but also to the nature of surface–water interactions. For geometries widely studied, namely, water confined in a narrow slit, nanocylinder, and nanospherical cavity, the asymptotic approach to the bulk value of the DC with the increase in confinement size is found to be surprisingly slow. This seems to imply the appearance of a dipolar cross correlation length, much larger than the molecular length-scale of water. In narrow slits and narrow cylinders, the dielectric function becomes both inhomogeneous and anisotropic, and the longitudinal and transverse components display markedly different system size dependencies. This sensitivity can be traced back to the dependence of the DC on the ratio of the mean square dipole moment fluctuation to the volume of the system. The observed sensitivity of collective dipole moment fluctuations to the length scale of confinement points to the possibility of using DC to estimate the orientational correlation length scale, which has been an elusive quantity. Furthermore, the determination of volume also requires special consideration when the system size is in nanoscale. We discuss these and several other interesting issues along with several applications that have emerged in recent years. [ABSTRACT FROM AUTHOR]

Unlike with the energy, which is a scalar property, machine learning (ML) prediction of vector or tensor properties poses the additional challenge of achieving proper invariance (covariance) with respect to molecular rotation. For the energy gradients needed in molecular dynamics (MD), this symmetry is automatically fulfilled when taking analytic derivative of the energy, which is a scalar invariant (using properly invariant molecular descriptors). However, if the properties cannot be obtained by differentiation, other appropriate methods should be applied to retain the covariance. Several approaches have been suggested to properly treat this issue. For nonadiabatic couplings and polarizabilities, for example, it was possible to construct virtual quantities from which the above tensorial properties are obtained by differentiation and thus guarantee the covariance. Another possible solution is to build the rotational equivariance into the design of a neural network employed in the model. Here, we propose a simpler alternative technique, which does not require construction of auxiliary properties or application of special equivariant ML techniques. We suggest a three-step approach, using the molecular tensor of inertia. In the first step, the molecule is rotated using the eigenvectors of this tensor to its principal axes. In the second step, the ML procedure predicts the vector property relative to this orientation, based on a training set where all vector properties were in this same coordinate system. As the third step, it remains to transform the ML estimate of the vector property back to the original orientation. This rotate–predict–rotate (RPR) procedure should thus guarantee proper covariance of a vector property and is trivially extensible also to tensors such as polarizability. The RPR procedure has an advantage that the accurate models can be trained very fast for thousands of molecular configurations, which might be beneficial where many training sets are required (e.g., in active learning). We have implemented the RPR technique, using the MLatom and Newton-X programs for ML and MD, and performed its assessment on the dipole moment along MD trajectories of 1,2-dichloroethane. [ABSTRACT FROM AUTHOR]

A spin–orbit coupling electronic structure study of the AlZn molecule is conducted to investigate the molecular properties of the low-lying electronic states and their feasibility toward direct laser cooling. This study uses the complete active-space self-consistent field level of theory, followed by the multireference configuration interaction method with Davidson correction (+Q). The potential energy and dipole moment curves and the spectroscopic constants are computed for the low-lying doublet and quartet electronic states in the 2S+1Λ± and Ω(±) representations. The transition dipole moments, the Franck–Condon factors, the Einstein coefficient, the radiative lifetimes, the vibrational branching ratio, and the slowing distance are determined between the lowest spin–orbit bound electronic states. These results show that the molecule AlZn has a high potential for laser cooling through the X2Π1/2 → (2)2Π1/2 transition by utilizing four lasers at a wavelength in the ultraviolet region, reaching a sub-microkelvin temperature limit. [ABSTRACT FROM AUTHOR]

In excited centrosymmetric donor–acceptor triads of type A–D–A or D–A–D, symmetry breaking charge transfer (SBCT) in polar media has been explored for a few decades. SBCT is accompanied by significant reorganization of the electronic structure of the molecule, which leads to a change in the fluorescence transition dipole moment (TDM). Previously, experiments revealed a 20%–30% reduction in TDM, which occurs on the timescale of SBCT. Simple SBCT models explain this reduction. Here, the effect of the interaction of a locally excited state with zwitterionic states on TDM is investigated. This interaction is shown to have a drastic impact on the TDM and its dependence on the solvent polarity. The magnitude of TDM can decrease monotonically, increase monotonically, and also pass through a maximum with an increase in the SBCT degree due to the locally excited state effect. The scale of changes in TDM in the course of SBCT increases greatly. The conditions for the implementation of a particular scenario have been determined. This work clearly demonstrates the observable influence of upper excited states on the photochemistry and photophysics of molecules. Methods for controlling the fluorescent characteristics of quadrupolar molecules are proposed. [ABSTRACT FROM AUTHOR]

We explore the dynamics of energy transfer between two nanocrystal quantum dots placed within an optical microcavity. By adjusting the coupling strength between the cavity photon mode and the quantum dots, we have the capacity to fine-tune the effective coupling between the donor and acceptor. Introducing a non-adiabatic parameter, γ, governed by the coupling to the cavity mode, we demonstrate the system's capability to shift from the overdamped Förster regime (γ ≪ 1) to an underdamped coherent regime (γ ≫ 1). In the latter regime, characterized by swift energy transfer rates, the dynamics are influenced by decoherence time. To illustrate this, we study the exciton energy transfer dynamics between two closely positioned CdSe/CdS core/shell quantum dots with sizes and separations relevant to experimental conditions. Employing an atomistic approach, we calculate the excitonic level arrangement, exciton–phonon interactions, and transition dipole moments of the quantum dots within the microcavity. These parameters are then utilized to define a model Hamiltonian. Subsequently, we apply a generalized non-Markovian quantum Redfield equation to delineate the dynamics within the polaritonic framework. [ABSTRACT FROM AUTHOR]

Understanding how external electric fields (EFs) impact the properties of aqueous molecules is crucial for various applications in chemistry, biology, and engineering. In this paper, we present a study utilizing molecular dynamics simulation to explore how direct-current (DC) and alternative-current (AC) EFs affect hydrophobic (n-triacontane) and hydrophilic (PEG-10) oligomer chains. Through a machine learning approach, we extract a 2-dimensional free energy (FE) landscape of these molecules, revealing that electric fields modulate the FE landscape to favor stretched configurations and enhance the alignment of the chain with the electric field. Our observations indicate that DC EFs have a more prominent impact on modulation compared to AC EFs and that EFs have a stronger effect on hydrophobic chains than on hydrophilic oligomers. We analyze the orientation of water dipole moments and hydrogen bonds, finding that EFs align water molecules and induce more directional hydrogen bond networks, forming 1D water structures. This favors the stretched configuration and alignment of the studied oligomers simultaneously, as it minimizes the disruption of 1D structures. This research deepens our understanding of the mechanisms by which electric fields modulate molecular properties and could guide the broader application of EFs to control other aqueous molecules, such as proteins or biomolecules. [ABSTRACT FROM AUTHOR]

Electron dynamics of the Na10 chain and the Na10–N2 complex locally excited by an atomistic optical near-field are investigated using real-time time-dependent density functional theory calculations on real-space grids. Ultrafast laser pulses were used to simulate the near-field excitation under on- and off-resonance conditions. Off-resonance excitation did not lead to the propagation of the excitation through the Na10 chain. In contrast, under the resonance conditions, the excited state is delocalized over the entire Na chain. Analysis of the local dipole moment of each atom in Na10 indicates that this behavior is consistent with the transition density. Adding an N2 molecule to the opposite end of the local excitation region results in energy transfer via the Na10 chain. The energy transfer efficiency of the N2 molecule is well correlated with the absorption spectrum of Na10. The present study paves the way for realizing remote excitation and photonic devices at the atomic scale. [ABSTRACT FROM AUTHOR]

The dielectric constant is a critical parameter in many energy-related applications. Typically, increasing the dielectric constant of soft materials involves adding high dielectric constant polar liquids or inorganic fillers, but there are limitations to this approach due to safety concerns with volatile and flammable solvents and the agglomeration of inorganic fillers. An alternative approach is to add zwitterionic liquids that exhibit exceptionally high dielectric constants with negligible volatility. Here, we report the synthesis of a series of zwitterionic liquids containing an imidazolium cation, exhibiting the highest dielectric constant among all organic molecules (∼350 at 293 K). The cation–anion linkage was tailored in a wide range between three and nine carbons, rendering the zwitterion dipole from 25 to 52 D. Comparing the dielectric constant for zwitterions with different anions (i.e., sulfonylimide, sulfonate, and carboxylate) reveals the beneficial impacts of the delocalized sulfonylimide anion vs the carboxylate anion due to the enlarged molecular dipole and more homogenous liquid morphology. Molecular dipole and liquid morphology are identified as the keys to developing high dielectric constant zwitterionic liquids. The extremely high dielectric constant accessible with the proposed molecular design paves new avenues for developing high dielectric constant zwitterions that act as dielectricizers. [ABSTRACT FROM AUTHOR]

In this work, we introduce a differentiable implementation of the local natural orbital coupled cluster (LNO-CC) method within the automatic differentiation framework of the PySCFAD package. The implementation is comprehensively tuned for enhanced performance, which enables the calculation of first-order static response properties on medium-sized molecular systems using coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. We evaluate the accuracy of our method by benchmarking it against the canonical CCSD(T) reference for nuclear gradients, dipole moments, and geometry optimizations. In addition, we demonstrate the possibility of property calculations for chemically interesting systems through the computation of bond orders and Mössbauer spectroscopy parameters for a [NiFe]-hydrogenase active site model, along with the simulation of infrared spectra via ab initio LNO-CC molecular dynamics for a protonated water hexamer. [ABSTRACT FROM AUTHOR]

The S vacancy at metal/ MoS 2 interface plays a much important role than the semiconductor itself. In this work, the influence of different configurations of S vacancy concentrations on the effective work function and band structure of the Au/ MoS 2 interface has been investigated systematically using first-principles calculations. The study specifically explores the effective work function of the Au/ MoS 2 interface, the deviation of interface effects from the vacuum work function, and the dipole moment caused by interface charge transfer. The results reveal that the electronic work function of Au/ MoS 2 increases with the increase in S vacancy concentration, but the rate of increase tends to slow down with higher S concentrations. The variation in the effective work function of the Au/ MoS 2 interface may be attributed to the presence of S vacancies and the exposure of Mo atoms. S vacancies lead to a reduction in the Schottky barrier, resulting in increased leakage current. The Fermi pinning caused by S vacancy concentration and location is also observed. The results obtained in this study can serve as a theoretical foundation for applications in electronic devices that rely on metal/ MoS 2 contact. [ABSTRACT FROM AUTHOR]

The lack of observational data for the AlO molecule in the mesosphere/lower thermosphere may be due to ablated aluminum reacting quickly to form other species. Previously proposed reaction pathways show that aluminum could be ablated in the atmosphere from meteoritic activity, but there currently exist very limited spectroscopic data on the intermediates in these reactions, limiting the possible detection of said molecules. As such, rovibrational spectroscopic data are computed herein using quartic force field methodology at four different levels of theory for the neutral intermediates AlCO3, OAlO2, and HOAlO2. Each molecule exhibits multiple vibrational modes with large vibrational transition intensities. For instance, the C–O stretch (ν1) in AlCO3 has a harmonic intensity of 536 km mol−1, the Al–O stretch (ν2) in OAlO2 has an intensity of 678 km mol−1, and the out-of-plane torsion (ν9) in HOAlO2 has an intensity of 158 km mol−1. All three molecules have exceptionally large dipole moments of 6.27, 4.21, and 5.04 D, respectively. These properties indicate that all three molecules are good candidates for potential atmospheric observation utilizing vibrational and/or rotational spectroscopic techniques. [ABSTRACT FROM AUTHOR]

The structure of the energy levels of excited symmetric donor–acceptor octupolar molecules suggests a completely symmetric state and a degenerate doublet. For most molecules, the doublet is the first excited state, which is called the normal level order, but there are molecules with the reverse level order. Symmetry breaking charge transfer (SBCT) and its effect on the transient dipole moment in these structures are studied. It has been established that for reverse level order, SBCT is possible only if the reorganization energy exceeds a certain threshold, whereas for the normal level order, there is no such threshold. The lowest completely symmetric excited state is shown to become bright after SBCT. The dependence of the fluorescence transition dipole moment on the SBCT extent is calculated. It was established that the direction and magnitude of the transition dipole moment change similarly to the change in the dipole moment for the reverse level order, whereas for the normal level order, the changes are opposite. The effect of solvent thermal fluctuations on the transition dipole moment is simulated and discussed. A way for controlling the direction of the transition dipole moment by an external electric field is suggested. [ABSTRACT FROM AUTHOR]

We present new results on the underlying guest–host interactions and spectral characterization of a CO2 molecule confined in the cages of the sI clathrate hydrate. Such types of porous solids raise computational challenges, as they are of practical interest as gas storage/capture materials. Accordingly, we have directed our efforts toward addressing their modeling in a proper manner, ensuring the quality of the input data and the efficiency of the computational approaches. The computational procedure for spectral simulations, within the multi-configurational time-dependent Hartree framework, involves the development of a fully coupled Hamiltonian, including an exact kinetic energy operator and a many-body representation of the potential, along with dipole moment surfaces, both obtained through neural network machine learning techniques. The resulting models were automatically trained and tested on extensive datasets generated by PW86PBE-XDM calculations, following the outcome of previous benchmark studies. Our simulations enable us to explore various aspects of the quantized dynamics upon confinement of CO2@D/T, such as constrained rotational–translational quantum motions and the averaged position/orientation of the CO2 guest in comparison to the experimental data available. Particularly notable are the distinct energy patterns observed in the computed spectra for the confined CO2 in the D and T cages, with a considerably high rotational–translational coupling in the CO2@T case. Leveraging reliable computations has proved instrumental, highlighting the sensitivity of the spectral features to the shape and strength of the potential interactions, with the explicit description of many-body contributions being significant. [ABSTRACT FROM AUTHOR]

When using metal–organic frameworks (MOFs) as electric field-dependent sensor devices, understanding their dielectric response is crucial as the orientation of polar groups is largely affected by confinement. To shed light on this at the molecular level, the response to a static field was computationally investigated for two structurally related MOFs, depending on their loading with guest molecules. The pillared-layer MOFs differ in their pillar moiety, with one bearing a rotatable permanent dipole moment and the other being non-polar. Two guest molecules with and without polarity, namely, methanol and methane, were considered. A comprehensive picture of the response of the guest molecules could be achieved with respect to both the amount and polarity of the confined species. For both MOFs, the dielectric response is very sensitive to the introduction of methanol, showing an anisotropic and non-linear increase in the system's relative permittivity expressed by a strongly increasing polarization response to external electric fields scaling with the number of confined methanol molecules. As expected, the effect of methane in the non-dipolar MOF is negligible, whereas subtle differences can be observed for the dipolar response of the MOF with rotatable dipolar linker groups. Taking advantage of these anisotropic and guest-molecule-specific confinement effects may open pathways for future sensing applications. Finally, methanol-induced global framework dynamics were observed in both MOFs. [ABSTRACT FROM AUTHOR]

Experiments have demonstrated that vibrational strong coupling between molecular vibrations and light modes can significantly change molecular properties, such as ground-state reactivity. Theoretical studies toward the origin of this exciting observation can roughly be divided into two categories, with studies based on Hamiltonians that simply couple a molecule to a cavity mode via its ground-state dipole moment on the one hand, and on the other hand ab initio calculations that self-consistently include the effect of the cavity mode on the electronic ground state within the cavity Born-Oppenheimer (CBO) approximation; these approaches are not equivalent. The CBO approach is more rigorous, but unfortunately it requires the rewriting of electronic-structure code, and its results may sometimes be hard to physically interpret. In this work, we exploit the relation between the two approaches and demonstrate on a real molecule (hydrogen fluoride) that for realistic coupling strengths, we can recover CBO energies and spectra to high accuracy using only out-of-cavity quantities from standard electronic-structure calculations. In doing so, we discover what thephysical effects underlying the CBO results are. Our methodology can aid in incorporating more possibly important features in models, play a pivotal role in demystifying CBO results, and provide a practical and efficient alternative to full CBO calculations. [ABSTRACT FROM AUTHOR]

A general formulation of the strong coupling between photons confined in a cavity and molecular electronic states is developed for the state-interaction state-average spin-restricted ensemble-referenced Kohn–Sham method. The light–matter interaction is included in the Jaynes–Cummings model, which requires the derivation and implementation of the analytical derivatives of the transition dipole moments between the molecular electronic states. The developed formalism is tested in the simulations of the nonadiabatic dynamics in the polaritonic states resulting from the strong coupling between the cavity photon mode and the ground and excited states of the penta-2,4-dieniminium cation, also known as PSB3. Comparison with the field-free simulations of the excited-state decay dynamics in PSB3 reveals that the light–matter coupling can considerably alter the decay dynamics by increasing the excited state lifetime and hindering photochemically induced torsion about the C=C double bonds of PSB3. The necessity of obtaining analytical transition dipole gradients for the accurate propagation of the dynamics is underlined. [ABSTRACT FROM AUTHOR]

J-aggregates, which are supramolecular assemblies that exhibit unique optical properties owing to their excitonic interactions, have potential applications in artificial light-harvesting systems and fluorescence biosensing. Although J-aggregates are formed in solution, in situ observations of their structures and behaviors in solution remain scarce. In this study, we investigated the J-aggregates of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate [DiIC18(3)] in methanol/water (M/W) binary solvents using fluorescence imaging as well as polarized absorption and fluorescence measurements to explore the relationship between their structure and macroscopic optical properties under static conditions. Fluorescence images revealed that the DiIC18(3) J-aggregates have fibrous structures in the M/W = 44/56 (v/v) binary solvent. We measured the polarization-angle dependence of the fluorescence intensity of the fibrous J-aggregates to determine the direction of their transition dipole moment. Furthermore, the J-band absorbance was dependent on the polarization angle of the linearly polarized incident light, even in the absence of an external force such as that generated by a flow or stirring, indicating that the J-aggregates "spontaneously" aligned in solution. We also monitored the time evolution of the degree of alignment of the fibrous J-aggregates, which revealed that the formation and elongation of the fibers induced their alignment, resulting in the observed macroscopic optical anisotropy in solution. [ABSTRACT FROM AUTHOR]

Fluorescence-encoded infrared (FEIR) spectroscopy is a recently developed technique for solution-phase vibrational spectroscopy with detection sensitivity at the single-molecule level. While its spectroscopic information content and important criteria for its practical experimental optimization have been identified, a general understanding of the electronic and nuclear properties required for highly sensitive detection, i.e., what makes a molecule a "good FEIR chromophore," is lacking. This work explores the molecular factors that determine FEIR vibrational activity and assesses computational approaches for its prediction. We employ density functional theory (DFT) and its time-dependent version (TD-DFT) to compute vibrational and electronic transition dipole moments, their relative orientation, and the Franck–Condon factors involved in FEIR activity. We apply these methods to compute the FEIR activities of normal modes of chromophores from the coumarin family and compare these predictions with experimental FEIR cross sections. We discuss the extent to which we can use computational models to predict the FEIR activity of individual vibrations in a candidate molecule. The results discussed in this work provide the groundwork for computational strategies for choosing FEIR vibrational probes or informing the structure of designer chromophores for single-molecule spectroscopic applications. [ABSTRACT FROM AUTHOR]

We combine on-the-fly trajectory surface hopping simulations and the doorway–window representation of nonlinear optical response functions to create an efficient protocol for the evaluation of time- and frequency-resolved fluorescence (TFRF) spectra and anisotropies of the realistic polyatomic systems. This approach gives the effective description of the proper (e.g., experimental) pulse envelopes, laser field polarizations, and the proper orientational averaging of TFRF signals directly from the well-established on-the-fly nonadiabatic dynamic simulations without extra computational cost. To discuss the implementation details of the developed protocol, we chose cis-azobenzene as a prototype to simulate the time evolution of the TFRF spectra governed by its nonadiabatic dynamics. The results show that the TFRF is determined by the interplay of several key factors, i.e., decays of excited-state populations, evolution of the transition dipole moments along with the dynamic propagation, and scaling factor of the TFRF signals associated with the cube of emission frequency. This work not only provides an efficient and effective approach to simulate the TFRF and anisotropies of realistic polyatomic systems but also discusses the important relationship between the TFRF signals and the underlining nonadiabatic dynamics. [ABSTRACT FROM AUTHOR]

Polaritonic states, which are formed by resonances between a molecular excitation and the photonic mode of a cavity, have a number of useful properties that offer new routes to control molecular photochemistry using electric fields. To provide a theoretical description of how polaritonic states affect the real-time electron dynamics in molecules, a new method is described where the effects of strong light–molecule coupling are implemented using real-time electronic structure theory. The coupling between the molecular electronic states and the cavity is described by the Pauli–Fierz Hamiltonian, and transitions between polaritonic states are induced via an external time-dependent electric field using time-dependent configuration interaction (TDCI) theory, producing quantum electrodynamics TDCI (QED-TDCI). This method is used to study laser-induced ultrafast charge transfer and dipole-switching dynamics of the LiCN molecule inside a cavity. The increase in cavity coupling strength is found to have a significant impact on the energies and transition dipole moments of the molecule–cavity system. The convergence of the polaritonic state energies as a function of the number of included electronic and photonic basis states is discussed. [ABSTRACT FROM AUTHOR]

The effect of a locally excited state on charge transfer symmetry breaking (SBCT) in excited quadrupolar molecules in solutions has been studied. The interaction of a locally excited state and two zwitterionic states is found to either increase or decrease the degree of SBCT depending on the molecular parameters. A strategy on how to adjust the molecular parameters to control the extent of SBCT is presented. The influence of level degeneracy on SBCT is identified and discussed in detail. The level degeneracy is shown to lead to the existence of a hidden dipole moment in excited quadrupolar molecules. Its manifestations in SBCT are analyzed. The main conclusions are consistent with the available experimental data. [ABSTRACT FROM AUTHOR]

We formulate a contraction theorem that maps quantum dynamics of a multilevel degenerate system (DS) driven by a time-dependent external field to the dynamics of the corresponding contracted non-degenerate system (CNS) of lower dimension, provided transitions between each pair of degenerate levels in the DS have identical transition dipole moments. The theorem is valid for an external field of any strength and shape, with and without rotating wave approximation in the system–field interaction. It establishes explicit relations between DS and CNS observables, significantly simplifies numerical calculations, and clarifies physical origins of the field-induced DS dynamics. [ABSTRACT FROM AUTHOR]

We extend some of the well-established self-interaction correction (SIC) schemes of density-functional theory—the Perdew–Zunger SIC and the average-density SIC—to the case of systems with noncollinear magnetism. Our proposed SIC schemes are tested on a set of molecules and metallic clusters in combination with the widely used local spin-density approximation. As expected from the collinear SIC, we show that the averaged-density SIC works well for improving ionization energies but fails to improve more subtle quantities like the dipole moments of polar molecules. We investigate the exchange-correlation magnetic field produced by our extension of the Perdew–Zunger SIC, showing that it is not aligned with the local total magnetization, thus producing an exchange-correlation torque. [ABSTRACT FROM AUTHOR]

Fluorescence-encoded infrared (FEIR) spectroscopy is an emerging technique for performing vibrational spectroscopy in solution with detection sensitivity down to single molecules. FEIR experiments use ultrashort pulses to excite a fluorescent molecule's vibrational and electronic transitions in a sequential, time-resolved manner, and are therefore sensitive to intervening vibrational dynamics on the ground state, vibronic coupling, and the relative orientation of vibrational and electronic transition dipole moments. This series of papers presents a theoretical treatment of FEIR spectroscopy that describes these phenomena and examines their manifestation in experimental data. This first paper develops a nonlinear response function description of Fourier-transform FEIR experiments for a two-level electronic system coupled to multiple vibrations, which is then applied to interpret experimental measurements in the second paper [L. Whaley-Mayda et al., J. Chem. Phys. 159, 194202 (2023)]. Vibrational coherence between pairs of modes produce oscillatory features that interfere with the vibrations' population response in a manner dependent on the relative signs of their respective Franck–Condon wavefunction overlaps, leading to time-dependent distortions in FEIR spectra. The orientational response of population and coherence contributions are analyzed and the ability of polarization-dependent experiments to extract relative transition dipole angles is discussed. Overall, this work presents a framework for understanding the full spectroscopic information content of FEIR measurements to aid data interpretation and inform optimal experimental design. [ABSTRACT FROM AUTHOR]

We present a method for calculating first-order response properties in phaseless auxiliary field quantum Monte Carlo by applying automatic differentiation (AD). Biases and statistical efficiency of the resulting estimators are discussed. Our approach demonstrates that AD enables the calculation of reduced density matrices with the same computational cost scaling per sample as energy calculations, accompanied by a cost prefactor of less than four in our numerical calculations. We investigate the role of self-consistency and trial orbital choice in property calculations. We find that orbitals obtained using density functional theory perform well for the dipole moments of selected molecules compared to those optimized self-consistently. [ABSTRACT FROM AUTHOR]

Ultra‐high molecular weight polyethylene (UHMWPE) fiber, with excellent light resistance, and chemical resistance, is one of the most important high‐performance fibers. However, the high hydrophobicity and crystallinity make it difficult to color, restricting the development of colored fluorescent UHMWPE protection materials. In this study, three hydrophobic fluorescent dyes (NC4, NC8, NC16) for fluorescent dyeing of UHMWPE were developed by introducing alkyl substituents of different lengths (butyl, octyl, and hexadecyl) and polar cyano groups onto 4‐NH‐1,8‐naphthalimide fluorescent chromophore. The relationship between the structures and the application performance was studied, and theoretical calculations were combined to explore the influence of the substituents on the spatial and electronic effects of fluorescent dyes. With the extension of the alkyl chain, the dye‐uptake rate and building‐up property was enhanced, and the equilibrium dye‐uptake rates for NC4, NC8, and NC16 were 18.21%, 93.22%, and 62.96%, respectively. NC8, which was proven to have high hydrophobicity and maximum dipole moment, exhibited the highest dye‐uptake rate. The dyed UHMWPE fabrics exhibited strong yellow‐green fluorescence. This study provides a facile strategy for constructing luminescent UHMWPE protection materials. [ABSTRACT FROM AUTHOR]

This study investigates the phenolic compounds (PC), volatile compounds (VC), and fatty acids (FA) of extra virgin olive oil (EVOO) derived from the Turkish olive variety "Sarı Ulak", along with ADMET, DFT, molecular docking, and gene network analyses of significant molecules identified within the EVOO. Chromatographic methods (GC-FID, HPLC) were employed to characterize FA, PC, and VC profiles, while quality parameters, antioxidant activities (TAC, ABTS, DPPH) were assessed via spectrophotometry. The analysis revealed a complex composition of 40 volatile compounds, with estragole, 7-hydroxyheptene-1, and 3-methoxycinnamaldehyde as the primary components. Hydroxytyrosol, tyrosol, oleuropein, apigenin, ferulic acid, and vanillic acid emerged as main phenolic constituents, with hydroxytyrosol and apigenin exhibiting high bioavailability. Molecular docking highlighted oleuropein and pinoresinol as compounds with strong binding affinities, though only hydroxytyrosol, apigenin, and pinoresinol fully met Lipinski and other drug-likeness criteria. DFT analysis showed that oleuropein and pinoresinol have notable dipole moments, reflecting polar and asymmetrical structures. KEGG enrichment analysis further linked key molecules like oleuropein and apigenin with pathways related to lipid metabolism and atherosclerosis, underscoring their potential bioactivity and relevance in health-related applications. [ABSTRACT FROM AUTHOR]

Oligothiophenes have attracted a lot of attention due to their excellent photoelectric properties. However, the effects of ring fusion and furan substitution on the optoelectrical properties of oligothiophenes are still unclear. In this study, based on popular pentathiophene, eight molecules including three ring‐fused and five furan‐substituted derivatives are systematically designed, and their frontier molecular orbitals, dipole moments, planarity, exciton binding energy (Eb), singlet‐triplet energy differences, and fluorescence quantum yields are calculated. The computed data demonstrate that full‐ring fusion and two‐ and more‐furan substitutions can greatly enhance the fluorescence quantum yields. Five potential molecules with about 100% of fluorescence quantum yield, i.e., TTTTT, SOSOS, OSOSO, SOOOS, and OOOOO, are screened. The results show that to obtain high fluorescence quantum yield, high Eb is required, and the flexible torsional displacement during the excitation from ground to the first excited state should be removed as much as possible. This work sheds some light on the future design of high‐performance oligothiophene‐based fluorescent materials. [ABSTRACT FROM AUTHOR]

Single‐junction perovskite solar cells (PSCs) have achieved certified power conversion efficiencies (PCEs) of 26.1%, which approaches their practical performance limit. Multi‐junction tandem solar cells can unlock even higher PCEs, where narrow‐bandgap lead‐tin (Pb‐Sn) perovskites, with a bandgap of 1.21–1.25 eV, are well‐suited as the bottom photo absorber in all‐perovskite tandems. Bulk engineering and surface treatments of Pb‐Sn perovskites using Lewis base molecules have been shown to reduce the defect density within the bulk and at the electron transport layer interface, thereby improving device performance. Nevertheless, the buried interface between Pb‐Sn perovskite and the commonly used hole transport layer PEDOT:PSS remains problematic due to the reactivity of polystyrene sulfonate (PSS) with Sn2+ ions, which negatively impacts device performance. To overcome this issue, a novel carbazole‐based self‐assembled monolayer, BrNH3‐4PACz is synthesized, that provides a suitable dipole moment at the indium‐tin oxide interface for efficient hole extraction and features an ionic ammonium head group that passivates the perovskite at the buried interface. This dual functionality enabled the fabrication of a p‐i‐n architecture Pb‐Sn PSC with a bandgap of 1.24 eV, achieving a champion PCE of 23% and an open‐circuit voltage of 0.88 V, which ranks among the highest reported values in the literature. [ABSTRACT FROM AUTHOR]

Disordered polymer chain entanglements within all‐polymer blends limit the formation of optimal donor‐acceptor phase separation. Therefore, developing effective methods to regulate morphology evolution is crucial for achieving optimal morphological features in all‐polymer organic solar cells (APSCs). In this study, two isomers, 4,5‐difluorobenzo‐c‐1,2,5‐thiadiazole (SF‐1) and 5,6‐difluorobenzo‐c‐1,2,5‐thiadiazole (SF‐2), were designed as solid additives based on the widely‐used electron‐deficient benzothiadiazole unit in nonfullerene acceptors. The incorporation of SF‐1 or SF‐2 into PM6 : PY‐DT blend induces stronger molecular packing via molecular interaction, leading to the formation of continuous interpenetrated networks with suitable phase‐separation and vertical distribution. Furthermore, after treatment with SF‐1 and SF‐2, the exciton diffusion lengths for PY‐DT films are extended to over 40 nm, favoring exciton diffusion and charge transport. The asymmetrical SF‐2, characterized by an enhanced dipole moment, increases the power conversion efficiency (PCE) of PM6 : PY‐DT‐based device to 18.83 % due to stronger electrostatic interactions. Moreover, a ternary device strategy boosts the PCE of SF‐2‐treated APSC to over 19 %. This work not only demonstrates one of the best performances of APSCs but also offers an effective approach to manipulate the morphology of all‐polymer blends using rational‐designed solid additives. [ABSTRACT FROM AUTHOR]

A new phosphorous mononitride (⁠|$^{31}$| P |$^{14}$| N and |${}^{31}$| P |${}^{15}$| N) line list PaiN covering infrared, visible, and ultraviolet regions is presented. The PaiN line list extending to the |$A\, {}^{1}\Pi$| – |$X\, {}^{1}\Sigma ^{+}$| vibronic band system replaces the previous YYLT ExoMol line list for PN. A thorough analysis of high-resolution experimental spectra from the literature involving the |$X\, {}^{1}\Sigma ^{+}$| and |$A\, {}^{1}\Pi$| states is conducted, and many perturbations to the |$A\, {}^{1}\Pi$| energies are considered as part of a comprehensive MARVEL (Measured-Active-Rotational-Vibrational-Energy-Levels) study. Ab initio potential energy and coupling curves from the previous work are refined by fitting their analytical representations to 1224 empirical energy levels determined using the MARVEL procedure. The PaiN line list is compared to previously observed spectra, recorded and calculated lifetimes, and previously calculated partition functions. The ab initio transition dipole moment curve for the A – X band is scaled to match experimentally measured lifetimes. The line list is suitable for temperatures up to 5000 K and wavelengths longer than 121 nm. PaiN is available from www.exomol.com. [ABSTRACT FROM AUTHOR]

The solubility of these materials in Cyrene was determined through the laser dynamic method. Experimental results indicate that the solubility order of the four energetic materials is as follows: ${x_{Fox}} \lt {x_{HMX}} \lt {x_{RDX}} \lt {x_{CL - 20}}$xFox

The formation of electric dipoles at the buried interface through self‐assembled molecules is crucial for minimizing non‐radiative recombination and improving the efficiency of inverted perovskite solar cells. However, creating dipoles at the upper interface has seldom been reported in the literature, primarily due to the scarcity of suitable n‐type organic passivants, film sensitivity of perovskite, and chemisorption issues. In this study, a novel bimolecular host–guest strategy is proposed utilizing the cavity of crown ether as the host and the ammonia ion as the guest. The ion‐docking phenomenon is thoroughly examined through a comprehensive range of experimental characterizations and theoretical analyses, instilling confidence in the robustness of the findings. These findings demonstrate that the host–guest electrostatic interlocking induces an electric dipole at the perovskite surface, which facilitates electron extraction and prevents hole recombination. As a result, a power conversion efficiency of 25.25% is achieved with minimal photovoltage and non‐radiative recombination losses. The target devices also exhibited superior long‐term stabilities under high humid and high temperature environments. [ABSTRACT FROM AUTHOR]

To further explore the mechanofluorochromic properties of benzophenone derivatives and their potential applications, two asymmetric benzophenone-based difluoroboron compounds (TPA-BP-BF2-1 and TPA-BP-BF2-2) were designed and synthesized. It was found that the emission spectrum of the solid powder was red-shifted from 520 nm to 562 nm under the stimulation of mechanical force for compound TPA-BP-BF2-2 with a 3,5-di-tert-butyl salicylaldehyde moiety. Its luminescent color underwent a conspicuous change, and its mechanofluorochromic behavior was reversible after fumigation, which was caused by a phase transition between the crystalline and amorphous states. However, compound TPA-BP-BF2-1 with a 3-tert-butyl salicylaldehyde section did not exhibit MFC behavior due to its amorphous stacking mode and a smaller difference value of the dipole moment between the ground and excited states. The two compounds could be used as developers to detect latent fingerprints on the surface of glass, based on their aggregation-induced emission performance in THF/water mixture. Additionally, compound TPA-BP-BF2-2 could be fabricated as a simple LED paint-coating according to its reversible mechanofluorochromic behavior. This work provides a reference for exploring the potential applications of benzophenone derivatives. [ABSTRACT FROM AUTHOR]

The computational, solvatochromism, and preferential solvation studies have been carried out on newly synthesized bio‐active azo dye molecules, namely 5‐[(E)‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)diazenyl]‐6‐hydroxy‐4‐methyl‐2‐oxo‐1,2‐dihydropyridine‐3‐carbonitrile (A1) and 5‐[(E)‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)diazenyl]‐6‐hydroxy‐1,4‐dimethyl‐2‐oxo‐1,2‐dihydropyridine‐3‐carbonitrile (A2). The electronic properties, chemical reactivity, and optical characteristics of the dye molecules have been computed using density functional theory (DFT). These findings suggest that the dye molecules are chemically active and show their suitability in NLO applications. The computations related to light‐harvesting properties have been carried out on the dye molecules. The ADME properties of the dye molecules have been evaluated using SwissADME and PreADMET online tools. The solvatochromic behavior of dye molecules has been investigated using Lippert's and Reichardt's solvent polarity parameters. The dye molecules' dielectric interactions and hydrogen bonding characteristics are analyzed using the Catalan multiple regression approach. The findings of the solvatochromic studies suggest the potentiality of the molecules in polarity sensing applications. Additionally, the solvatochromic data has been exploited to determine the excited state dipole moments using various solvatochromic approaches. The HOMO‐LUMO energy values, absorption wavelengths, light‐harvesting properties, and excited state dipole moments of the synthesized dye molecules indicate their suitability in dye‐sensitized solar cell applications. The preferential solvation studies of dye molecules have been conducted in a DCM–DMSO solvent mixture. [ABSTRACT FROM AUTHOR]

Inverted perovskite/organic tandem solar cells (P/O TSCs) suffer from poor long‐term device stability due to halide segregation in organic–inorganic hybrid wide‐band gap (WBG) perovskites, which hinders their practical deployment. Therefore, developing all‐inorganic WBG perovskites for incorporation into P/O TSCs is a promising strategy because of their superior stability under continuous illumination. However, these inorganic WBG perovskites also face some critical issues, including rapid crystallization, phase instability, and large energy loss, etc. To tackle these issues, two multifunctional additives based on 9,10‐anthraquinone‐2‐sulfonic acid (AQS) are developed to regulate the perovskite crystallization by mediating the intermediate phases and suppress the halide segregation through the redox‐shuttle effect. By coupling with organic cations having the desirable functional groups and dipole moments, these additives can effectively passivate the defects and adjust the alignment of interface energy levels. Consequently, a record Voc approaching 1.3 V with high power conversion efficiency (PCE) of 18.59 % could be achieved in a 1.78 eV band gap single‐junction inverted all‐inorganic PSC. More importantly, the P/O TSC derived from this cell demonstrates a T90 lifetime of 1000 h under continuous operation, presenting the most stable P/O TSCs reported so far. [ABSTRACT FROM AUTHOR]

Here in, we have designed two new unfused non‐fullerene small molecules using asymmetric benzo[1,2‐b:3.4‐b′, 6,5‐b"]trithiophene (BTT) as the central donor core and different terminal units i. e., 2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)malononitrile (NFA‐4) and 1,3‐diethyl‐2‐thioxodi hydropyrimidine‐4,6 (1H,5H)‐dione (NFA‐5) and examined their optical and electrochemical properties. Using a wide band‐gap copolymer D18, organic solar cells (OSCs) based on bulk heterojunction of D18:NFA‐4 and D18:NFA‐5 showed overall power conversion efficiency (PCE) of about 17.07 % and 11.27 %, respectively. The increased PCE for the NFA‐4‐based OSC, compared to NFA‐5 counterpart, is due higher value of short circuit current (JSC), open circuit voltage (VOC), and fill factor (FF). Following the addition of small amount of NFA‐5 to the binary bulk heterojunction D18:NFA‐4, the ternary organic solar cells attained a PCE of 18.05 %, surpassing that of the binary counterparts due to the higher values of which is higher than that for the binary counterparts and attributed to the increased values of JSC, FF, and VOC. The higher value of JSC is linked to the efficient use to excitons transferred from NFA‐5 to NFA‐4 with a greated dipole moment than NFA‐5 and subsequently dissociated into a free charge carrier efficiently. [ABSTRACT FROM AUTHOR]

In this study, we investigate the adsorption and sensing capabilities of pristine (MoSi2N4) and nitrogen‐vacancy induced (MoSi2N4−VN) monolayers towards five potential lung cancer volatile organic compounds (VOCs), such as 2,3,4‐trimethylhexane (C9H20), 4‐methyloctane (C9H20), o‐toluidine (C7H9N), Aniline (C6H7N), and Ethylbenzene (C8H10). Spin‐polarized density functional theory (DFT) calculations reveal that MoSi2N4 weakly adsorb the mentioned VOCs, whereas the introduction of nitrogen vacancies significantly enhances the adsorption energies (Eads ${{E}_{ads}}$), both in gas phase and aqueous medium. The MoSi2N4−VN monolayers exhibit a reduced bandgap and facilitate charge transfer upon VOCs adsorption, resulting in enhanced Eads ${{E}_{ads}}$ values of −0.83, −0.76, −0.49, −0.61, and −0.50 eV for 2,3,4‐trimethylhexane, 4‐methyloctane, o‐toluidine, Aniline, and Ethylbenzene, respectively. Bader charge analysis and spin‐polarized density of states (SPDOS) elucidate the charge redistribution and hybridization between MoSi2N4−VN and the adsorbed VOCs. The work function of MoSi2N4−VN is significantly reduced upon VOCs adsorption due to induced dipole moments, enabling smooth charge transfer and selective VOCs sensing. Notably, MoSi2N4−VN monolayers exhibit sensor responses ranging from 16.2 % to 26.6 % towards the VOCs, with discernible selectivity. Importantly, the recovery times of the VOCs desorption is minimal, reinforcing the suitability of MoSi2N4−VN as a rapid, and reusable biosensor platform for efficient detection of lung cancer biomarkers. Thermodynamic analysis based on Langmuir adsorption model shows improved adsorption and detection capabilities MoSi2N4−VN under diverse operating conditions of temperatures and pressures. [ABSTRACT FROM AUTHOR]

The study investigates CO2‐nanobubbles (NBs) generated from gas‐hydrate dissociation, exploring their impact on the physicochemical properties of liquid water. Raman spectroscopy evidenced a slight increase in the Raman‐band intensity, suggesting enhanced total hydration‐layer water‐dipole moment and polarity without affecting water molecule structuring. Furthermore, an overall decreasing trend for the zeta potential of NB solution can be observed due to the strong electron affinity on the surface of CO2 bulk NBs, probably caused by a negative charge accumulation. These findings are in good qualitative accord with molecular‐dynamics (MD) simulation results, wherein water can induce a small dipole moment of about 0.16 D for CO2 NBs, thereby increasing the polarity of the system. Due to the interaction between water molecules, the Coulombic or electrostatic forces increase in the presence of NBs compared to pure water, which can reflect the increase in the dipole moment of water molecules in the presence of NBs. The presence of NBs strengthens the local hydrogen‐bond network, leading to higher‐frequency vibrations. Additionally, NBs amplify the intrinsic electric field of the aqueous solution, causing the gas‐water interface to exhibit negatively charged characteristics, dependent on NB size. Molecular simulations agree qualitatively with experiments, emphasizing their utility in studying NB evolution in water. [ABSTRACT FROM AUTHOR]

Deeply electrolytic reduction of carbon dioxide (CO2) to high‐value ethylene (C2H4) is very attractive. However, the sluggish kinetics of C−C coupling seriously results in the low selectivity of CO2 electroreduction to C2H4. Herein, we report a copper‐based polyhedron (Cu2) that features uniformly distributed and atomically precise bi‐Cu units, which can stabilize *OCCO dipole to facilitate the C−C coupling for high selective C2H4 production. The C2H4 faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm−2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h−1) compared to Cu nanoparticles (~9.42 h−1) and Cu SAC (~0.87 h−1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C2H4. [ABSTRACT FROM AUTHOR]

Deeply electrolytic reduction of carbon dioxide (CO2) to high‐value ethylene (C2H4) is very attractive. However, the sluggish kinetics of C−C coupling seriously results in the low selectivity of CO2 electroreduction to C2H4. Herein, we report a copper‐based polyhedron (Cu2) that features uniformly distributed and atomically precise bi‐Cu units, which can stabilize *OCCO dipole to facilitate the C−C coupling for high selective C2H4 production. The C2H4 faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm−2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h−1) compared to Cu nanoparticles (~9.42 h−1) and Cu SAC (~0.87 h−1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C2H4. [ABSTRACT FROM AUTHOR]

A new series of ladder‐type heteroarenes electro‐optic (EO) chromophores based on unique fused oligothiophene, oligofuran, and oligopyrrole bridge with a strong push–pull effect were designed, and their distinctive electric structure and nonlinear optical (NLO) properties were investigated by multiple methods, including DOS analysis, CPKS method, SOS model, TSM model, and hyperpolarizability density analysis. Interestingly, it is found that the introduction of different strengths of donor and acceptor moieties, the nature of ladder‐type heteroarenes bridge, and the medium polarity play critical roles in achieving ultra‐large hyperpolarizabilities. Encouragingly, the DN1‐6Fu‐AS1 and DN1‐6Py‐AS1 both exhibit ultra‐large βprj values (up to 12965.5 × 10−30 esu) and βtot value (up to 13238.2 × 10−30 esu), owing to their exceptionally low transitions energy and large variation of dipole moment. The DO2‐6Fu‐AO2, DO2‐6Th‐AO2, DO2‐6Fu‐AS1, and DO2‐6Th‐AS1, exhibit very deep HOMO levels, which are expected to have superior air stability and effectively prevent large leakage currents. Hirshfeld surface analysis and interaction region indicator analysis were employed to explore the noncovalent interactions in the dimer. The DO2‐6Fu‐AS1 and DO2‐6Py‐AS1 show the outstanding electro‐optical Pockels effect, and DN1‐6Fu‐AO2 exhibit large SHG responses. These unique and brand‐new push‐pull ladder‐type heteroarenes chromophores are promising candidates for chip‐scale EO modulators, and electronic and photonic devices in emerging communication, energy, analog, and digital technologies. [ABSTRACT FROM AUTHOR]

Development of organic nonlinear optical materials has become progressively more important due to their emerging applications in new‐generation photonic devices. A novel series of chromophores based on innovative thiophene and furan‐fused cyclopentadienyl bridge with various powerful donor and acceptor moieties were designed and theoretically investigated for applications in nonlinear optics. To unravel the structure–property relationship between this new push‐pull conjugated systems and their nonlinear optical property, multiple methods, including density of states analysis, coupled perturbed Kohn–Sham (CPKS) method, sum‐over‐states (SOS) model, the two‐level model (TSM), hyperpolarizability density analysis, and the (hyper)polarizability contribution decomposition, were performed to comprehensively investigated the nonlinear optical and electronic properties of this new π‐system. Due to excellent charge transfer ability of new bridge and distinctive structure of donor and acceptor, the designed chromophores exhibit deep HOMO levels, low excitation energy, high dipole moment difference and large hyperpolarizability, indicating the appealing air‐stable property and remarkable electrooptic performance of them. Importantly, THQ‐CS‐A3 and PA‐CS‐A3 shows outstanding NLO response properties with βtot value of 6953.9 × 10−30 and 5066.0 × 10−30 esu in AN, respectively. The influence of the push‐pull strength, the heterocycle and the π‐conjugation of new bridge on the nonlinear optical properties of this novel powerful systems are clarified. This new series of chromophores exhibit remarkable electro‐optical Pockels and optical rectification effect. More interestingly, PA‐CS‐A3 and THQ‐CS‐A2 also show appealing SHG effect. This study will help people understand the nature of nonlinear optical properties of innovative heteroarene‐fused based cyclopentadienyl chromophores and offer guidance for the rational design of chromophores with outstanding electrooptic (EO) performance in the future. [ABSTRACT FROM AUTHOR]

Deeply electrolytic reduction of carbon dioxide (CO2) to high‐value ethylene (C2H4) is very attractive. However, the sluggish kinetics of C−C coupling seriously results in the low selectivity of CO2 electroreduction to C2H4. Herein, we report a copper‐based polyhedron (Cu2) that features uniformly distributed and atomically precise bi‐Cu units, which can stabilize *OCCO dipole to facilitate the C−C coupling for high selective C2H4 production. The C2H4 faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm−2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h−1) compared to Cu nanoparticles (~9.42 h−1) and Cu SAC (~0.87 h−1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C2H4. [ABSTRACT FROM AUTHOR]

Deeply electrolytic reduction of carbon dioxide (CO2) to high‐value ethylene (C2H4) is very attractive. However, the sluggish kinetics of C−C coupling seriously results in the low selectivity of CO2 electroreduction to C2H4. Herein, we report a copper‐based polyhedron (Cu2) that features uniformly distributed and atomically precise bi‐Cu units, which can stabilize *OCCO dipole to facilitate the C−C coupling for high selective C2H4 production. The C2H4 faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm−2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h−1) compared to Cu nanoparticles (~9.42 h−1) and Cu SAC (~0.87 h−1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C2H4. [ABSTRACT FROM AUTHOR]