ABSTRACT The diabatic potential energy surfaces (PESs) for the 1 1 A ′ and 2 1 A ′ states of CH 2 system were constructed using a neural network method combined with symmetry‐constrained function sin( α ). In ab initio calculations, the aug‐cc‐pVTZ basis set is adopted for both H and C atoms, and MRCI‐F12 method is used to compute the energies. Through comparison with ab initio energies and by examining the V 12 symmetry, the PES smoothness, and the minimum‐energy paths of V 11 and V 22 at different angles, we find that the diabatic matrix yields a smooth, symmetry‐adapted representation that accurately reproduces the adiabatic energies. To assess the nonadiabatic effects, we perform adiabatic and nonadiabatic calculations on the new PESs, presenting reaction probabilities, integral cross sections, and rate constants, and comparing them with previous theory and experiment. The results show that nonadiabatic values are slightly larger at low energies, while adiabatic values become larger at higher energies. Overall, the nonadiabatic results are in better agreement with the experimental trend than the adiabatic ones, confirming that nonadiabatic effects within the A ′ manifold are significant and must be included in quantitative dynamics studies. However, the absolute values of our calculated rate constants are lower than the most recent experimental measurements of Hickson et al., indicating that contributions from the 1 1 A ″ state are essential for a complete description of the total reaction rate.
ABSTRACT The intrinsic asymmetric surface reactivity of Janus WSTe monolayers is investigated using first‐principles calculations. The broken inversion symmetry generates a macroscopic polarization that manifests as an effective built‐in electric field of approximately 0.08 V/Å, driving spatial separation of frontier molecular orbitals and anisotropic orbital hybridization. The Te‐terminated surface exhibits a higher electrophilic Fukui function of 0.18 e/Å 3 , while the S‐terminated surface shows a higher nucleophilic Fukui function of 0.15 e/Å 3 . ELF analysis reveals diffuse delocalized electron basins at the Te‐terminated surface and compact localized basins at the S‐terminated surface. Hydrogen chemisorbs strongly at the S‐terminated surface with an adsorption energy of −2.33 eV, whereas carbon monoxide exhibits only weak physisorption. The preferential H adsorption at the S‐terminated surface correlates with its higher nucleophilic Fukui function, though the detailed orbital matching mechanism involves both the electron‐accepting character of the S site and the radical reactivity of the H atom. These results establish a quantum mechanical correlation among structural asymmetry, electronic structure, and surface chemical reactivity.
ABSTRACT This study employed density functional theory to investigate the metal–organic framework [Ag 24 (trz) 18 ] 6+ as a potential nanocarrier for ibuprofen (IBF), a nonsteroidal anti‐inflammatory drug. Encapsulation occurs through a physical process characterized by a favorable interaction energy of −62.37 kcal/mol, while preserving the structure of [Ag 24 (trz) 18 ] 6+ . Reactivity parameters indicate that both the isolated [Ag 24 (trz) 18 ] 6+ and the IBF@[Ag 24 (trz) 18 ] 6+ complex are chemically and kinetically stable. The LUMO energy suggests that [Ag 24 (trz) 18 ] 6+ prevents IBF from accepting electrons during chemical reactions. The IBF encapsulated within [Ag 24 (trz) 18 ] 6+ transfers part of its charge to the nanocage, maintaining its cavity partially in a neutral state. Additionally, quantum theory of atoms in molecules (QTAIM) and non‐covalent interaction (NCI) analyses indicate that the encapsulation is a physical process driven by van der Waals forces. Overall, our study suggests that the [Ag 24 (trz) 18 ] 6+ nanocage is a promising candidate for use as a nanocarrier for IBF.
ABSTRACT Using first‐principles DFT, we investigate the synergistic modulation of the electronic structure of monolayer MoSe 2 by biaxial strain and Frenkel defects for electrocatalytic hydrogen evolution. A biaxial compressive strain of −4% lowers the Frenkel defect formation energy from 2.41 eV to 1.85 eV. The defect‐strain synergy introduces in‐gap states, increases the density of states at the Fermi level, modulates the Mo d‐band center, strengthens orbital hybridization, and optimizes surface charge distribution and work function. Consequently, the hydrogen adsorption free energy (ΔG H* ) changes from 1.92 eV on the pristine basal plane to −0.01 eV, approaching the ideal thermodynamic value. Detailed analysis of the correlation between the d ‐band center and ΔG H* elucidates the microscopic origin of this optimization. Phonon dispersion and AIMD simulations confirm dynamical stability at room temperature. This work reveals the microscopic mechanism of strain–defect coupling in enhancing catalytic activity and provides a physical basis for the rational design of two‐dimensional transition metal dichalcogenide electrocatalysts for clean energy applications.
ABSTRACT Excited‐state proton transfer (ESPT) plays a crucial role in photochemical processes, serving as an important mechanism for modulating molecular structures and fluorescence behaviors. In this study, the ESPT mechanism of salicylamide (SAM) was systematically investigated in the gas phase, aqueous solution, and ethanol solution using density functional theory (DFT) and time‐dependent DFT (TD‐DFT) methods. Explicit solvent‐complex models were constructed to evaluate solvent effects. The calculated results indicate that ESPT is both thermodynamically and kinetically feasible for SAM in the gas phase. In contrast, in aqueous and ethanol environments, ESPT occurs through intermolecular proton transfer facilitated by solvent molecules, giving rise to dual fluorescence behavior. The primary fluorescence emission originates from the local excitation.
ABSTRACT A density functional theory study of CO 2 and the cyclic trimer 1,3,5‐trioxanetrione (C 3 O 6 ) coordination to Ni 2+ , Cu 2+ , and Zn 2+ is presented to elucidate how metal identity, ligand topology, and coordination environment govern multiligand binding thermodynamics. In the absence of coordinating anions, both CO 2 and C 3 O 6 follow an intrinsic affinity order of Ni 2+ > Cu 2+ > Zn 2+ . Successive ligand addition leads to cumulative stabilization for all metals, while decreasing per‐ligand interaction and free energies indicate progressive electronic saturation and coordination‐sphere crowding. Coordination of C 3 O 6 induces localized structural activation, reflected in characteristic C–O bond distortions that follow the same metal‐dependent trend. The ligand environment significantly modulates binding: weakly coordinating BF 4 − counterions reduce interaction strengths and alter relative affinities, whereas coordinating Cl − ligands occupy metal coordination sites and limit ligand accessibility. Despite these effects, Ni 2+ retains favorable binding across coordination numbers, while Cu 2+ and Zn 2+ show more limited coordination. Comparison with equivalent monomeric CO 2 assemblies reveals that the C 3 O 6 binding mode provides enhanced metal–ligand stabilization per CO 2 equivalent, arising from its cyclic, multidentate nature. Although this stabilization partially compensates the intrinsic endothermicity associated with C 3 O 6 formation, the process remains thermodynamically uphill with respect to CO 2 . Overall, the results highlight the interplay of metal electronic structure, coordination‐sphere crowding, counterion effects, and ligand preorganization in governing multiligand CO 2 binding.
ABSTRACT It was shown more than a decade ago [J. Chem. Phys. 139, 014108 (2013)] that a many‐electron relativistic quantum electrodynamics (QED) Hamiltonian for high‐precision electronic structure calculations can be constructed in a bottom‐up fashion, by virtue of charge‐conjugated contraction (CCC) of fermion operators when normal‐ordering the starting unbounded relativistic Hamiltonian (second‐quantized in terms of the electronic Dirac field) with respect to the filled negative‐energy Dirac sea of electrons. It is shown here that the same relativistic QED Hamiltonian can also be obtained by equal average of the two relativistic Hamiltonians resulting from the normal‐ordering of the starting unbounded relativistic Hamiltonians (second‐quantized in terms of the electronic and positronic Dirac fields, respectively) with respect to the filled negative‐energy Dirac seas of electrons and positrons, respectively, via the standard contraction of fermion operators. In essence, both procedures incorporate properly the fundamental charge‐conjugation symmetry of relativistic quantum mechanics to ensure the symmetric treatment of the electronic and positronic degrees of freedom.
ABSTRACT Endohedral metallofullerenes are unique carbon nanostructures in which metal atoms are encapsulated inside fullerene cages. In this work, two representative Nd@C 82 isomers, Nd@ C s (6)‐C 82 and Nd@ C 2v (9)‐C 82 , were systematically investigated using density functional theory and time‐dependent density functional theory to understand the effects of cage isomerism and Nd encapsulation on their electronic and spectroscopic properties. Spin‐state calculations reveal that the quintet state is the lowest‐energy electronic state for both Nd@C 82 isomers. The results show that Nd encapsulation regulates the frontier electronic structures and excited‐state transition behaviors of the C 82 frameworks. Optical analyses demonstrate that the absorption and nonlinear optical responses are mainly dominated by the fullerene cages, accompanied by moderate Nd–cage electronic coupling. ECD analyses further indicate that Nd encapsulation modulates chiroptical responses through electronic transition characteristics rather than introducing intrinsic chirality into the C 82 cages. Raman analyses reveal that the vibrational properties are primarily governed by the carbon frameworks, with only limited low‐frequency modes involving noticeable Nd motion. This work provides molecular‐level insights into the relationship between cage structures, metal–cage interactions, and spectroscopic properties in rare‐earth endohedral metallofullerenes.
ABSTRACT Crystal field (CF) as well as zero field splitting (ZFS) characteristics of Mn 2+ in single crystals of Ni Cs 2 (SO 4 ) 2 ·6H 2 O (NCS) are computationally described utilizing the superposition model (SPM) and angular overlap model (AOM). The ZFS parameters calculated with SPM match the EPR experiment values quite well. The CF energy levels of Mn 2+ : NCS crystals are determined using the crystal field analysis (CFA) tool. Additionally, the experimental and theoretical energy levels agree.
ABSTRACT The interactions of the Be + ion with the H 2 molecule and its isotopic variants are important for quantum information and ultracold chemistry. We performed quantum dynamics calculations for the Be + ( 2 S) + HD → BeH + /BeD + + D/H reaction using the time‐dependent wave packet method, based on the newly constructed ground‐state BeH 2 + potential energy surface (Molecules, 2024, 29, 3436). Strong intramolecular isotope effects and different dynamic mechanisms are seen on the two reaction channels. Reaction probabilities and branching ratios show that the formation of BeD + is strongly preferred throughout the entire investigated energy range. At relatively high collision energies, the differential cross sections show nearly forward‐backward symmetric scattering for the BeD + + H channel, while the BeH + + D channel exhibits forward scattering. Rovibrationally resolved integral cross sections show that the BeD + product mainly populates low‐vibrational, high‐rotational states, while the BeH + product exhibits a vibrationally hot and rotationally cold distribution. The quantum dynamics results show that the BeD + + H channel follows a complex‐forming mechanism, while the BeH + product is mainly generated through a direct abstraction mechanism. The dynamics data presented here could serve as a reference for finer experimental studies of the Be + ( 2 S) + HD reaction.
ABSTRACT Organic solar cells (OSCs), notably small‐molecules OSCs (SMOSCs), have gained considerable attention as promising photovoltaic technologies because of their well‐defined molecular structures, high batch reproducibility, and tunable electronic properties. Density functional theory (DFT) and time‐dependent DFT (TD‐DFT) have become powerful computational methods for investigating performance mechanisms and assisting high‐performance materials design. This review provides a comprehensive overview of recent advances in DFT‐guided design approaches for SMOSCs, emphasizing the role of computational parameters derived from DFT calculations in establishing robust structure–property–performance relationships. It further discusses fundamental theoretical and methodological aspects of DFT‐based modeling and analyzes the influence of frontier orbital energies, optical absorption properties, donor‐acceptor interfacial energetics, and charge‐transport descriptors on essential device parameters, like open‐circuit voltage, short‐circuit current density, and power conversion efficiency. Special attention is devoted to recent advances in small‐molecule donors and non‐fullerene acceptors for their role in improving device efficiency. By combining computational and experimental insights, it demonstrates the pivotal role of DFT‐based approaches in accelerating materials discovery and guiding molecular architecture optimization. These perspectives are aimed to support the rational design of next‐generation high‐performance organic photovoltaic systems.
ABSTRACT It is suggested that, under restrictive ideal circumstances, the interacting electronic energy of a system can be obtained directly from experimentally accessible x‐ray orbitals, defined here as orbitals obtained from direct fitting of the one‐body density matrix to measured x‐ray structure factors, through inverse Kohn–Sham equation functional integration. The argument rests on the identity, within a unitary transformation, between experimentally fitted x‐ray orbitals and theoretically calculated Kohn–Sham orbitals, both of which—in ideal circumstances—yield the same electron density. Using x‐ray orbitals, one may evaluate both the Kohn–Sham kinetic energy and the interacting potential energy by functional integration of the exact Kohn–Sham potential, taken directly from the Kohn–Sham equations, expressed in atomic units (a.u.), . This approach allows the total interacting Kohn–Sham energy: , where E KS is the interacting electronic energy, is the non‐interacting kinetic‐energy, and is the interacting electronic potential‐energy obtained from the Kohn–Sham potential , to be reconstructed entirely from orbital data measurable through high‐resolution x‐ray diffraction. A theorem is enunciated stating that for a non‐degenerate ground state, absent magnetic fields, in a real finite one‐particle basis, if the experimentally accessible constraints uniquely determine an idempotent rank‐ N x‐ray projector P XR , and if a Kohn–Sham projector P KS satisfies the same set of constraints, then the two projectors must be identical ( P XR = P KS ). Any remaining freedom corresponds only to unitary rotations within the occupied subspace and does not affect the projector itself. A mathematical development and an illustrative application to the beryllium atom are presented. Since this procedure reconstructs Kohn–Sham energies from diffraction‐constrained electronic structure, it offers an experimentally anchored route for benchmarking and evaluating approximate DFT exchange–correlation functionals via their associated potentials and energy decompositions.
ABSTRACT Janus 2D materials have many distinct properties because of lacking the mirror asymmetry. Electronic and optical properties, charge and quantum capacitance of MoSi 2 N x P 4− x monolayers are studied by density functional theory (DFT). MoSi 2 N 4 is an indirect semiconductor with bandgap of 1.84 eV, while MoSi 2 P 4 is a direct semiconductor. MoSi 2 N 2 P 2 is a Janus structure with N‐face versus P‐face, and exhibits half‐metallic character. Dirac cone is observed for MoSi 2 NPPN, which originates from Mo‐d, N‐p, and P‐p states. Built‐in electric field appears in Janus systems, and MoSi 2 NPNN has an internal electric field of 0.14 eV/Å. All systems have larger absorption for visible light, especially for MoSi 2 PNNN with 22.55%. The systems with more P atoms have better electrical conductivity, and MoSi 2 P 4 has the best electrical conductivity. MoSi 2 NNPP, MoSi 2 NPPN, MoSi 2 PNNN and MoSi 2 NPNP are anode materials, while other systems are favorable for cathode materials in aqueous system.
ABSTRACT The global diabatic potential energy surfaces (PESs) of the CH 2 ( 1 A″) system were constructed using the neural network method with symmetry‐constrained function based on 15 726 ab initio points. To achieve high accuracy, the MRCI‐F12 method and aug‐cc‐pVTZ basis set for C and H atoms were adopted in the ab initio calculations. The newly constructed diabatic PESs were examined in detail by comparison with the ab initio points. Furthermore, the topographic features of the diabatic PESs were described which indicate that the diabatic PESs present the non‐adiabatic transition processes reasonably between the electronic states. In addition, both adiabatic and non‐adiabatic dynamics calculations of the C( 1 D) + H 2 → CH(X 2 Π) + H reaction were carried out using the time‐dependent wave packet method. By comparing the adiabatic and non‐adiabatic results, it was found that non‐adiabatic effects play an important role in the reaction process, especially in the high collision energy region, where the adiabatic results underestimate the actual values.
ABSTRACT Two‐dimensional materials have garnered significant interest due to their exceptional physical and chemical properties, making them promising candidates for diverse technological applications. In this study, we conduct a rigorous investigation of the structural, dynamical, mechanical, electronic, optical, and thermoelectric properties of the 1T‐RbTe monolayer using first‐principles calculations based on density functional theory (DFT). Structural optimization and phonon dispersion analysis confirm the dynamic stability of the monolayer. The electronic band structure reveals an indirect semiconducting band gap of 1.86 eV, calculated using the hybrid HSE06 functional, ensuring accurate band gap prediction. The optical properties are analyzed through the complex dielectric function, revealing strong absorption in the visible and ultraviolet regions, with the absorption coefficient reaching values of cm and cm, respectively, thereby indicating suitability for optoelectronic applications. Thermoelectric performance is evaluated by calculating key parameters, including the Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit. The electronic figure of merit reaches a value of 0.72 at 300 K and increases up to 0.86 at 1000 K, indicating a strong potential for efficient conversion of thermal energy into electricity. Which demonstrates significant potential for efficient thermoelectric energy conversion. These comprehensive findings establish 1T‐RbTe as an auspicious material for integration into optoelectronic and thermoelectric devices.
ABSTRACT In order to demonstrate static and dynamic properties of molecular species/processes/phenomena involving complex electron‐nuclear couplings (namely, spin‐orbit (SO) interactions), Complex Beyond Born‐Oppenheimer (CBBO) theory has already been introduced for Abelian systems (two coupled electronic manifold) [ J. Chem. Theory Comput. , 2025, 21 , 10166‐10176], but the newly developed formulation needs to be generalized for non‐Abelian cases involving three or more than three coupled electronic states. In this context, the triatomic reactive scattering system, F+H can be considered as an excellent prototype system exhibiting profound non‐adiabatic as well as SO couplings within the low‐lying three electronic states (1A, 2A and 1A). The present work mainly focuses on the development of CBBO theory for three‐state sub‐Hilbert space (with and without SO couplings) and its applications for the titled system, F+H. The complex nature of SO coupling terms for F+H is reflected in the diabatic Hamiltonian, which is expected to produce more accurate dynamical properties (like spectral bands, reaction cross‐sections, rate constants, etc.) during nuclear dynamics calculations.
ABSTRACT Electrochemical CO 2 reduction reaction (CO 2 RR) to value‐added chemicals offers a promising route for carbon neutrality. It has been reported that the Co‐anchored SnS 2 monolayer (Co@SnS 2 ) exhibits exceptional catalytic performance in the CO 2 RR toward HCOOH production. As the most prevalent intrinsic point defect in SnS 2 , S‐vacancy may alter the catalytic performance. Herein, first‐principles calculations were employed to systematically study the effects of S‐vacancy on the CO 2 RR in Co@SnS 2 . The S‐vacancy near the doped‐Co atom affects the adsorption of CO 2 molecules and impairs the activation of CO 2 . Besides, it increases the free energy of the *COOH intermediate and disfavors the generation of the *HCOOH intermediate. Consequently, the presence of S‐vacancy diminishes the catalytic performance of the Co@SnS 2 monolayer for the CO 2 RR toward HCOOH. These findings enrich the fundamental understanding of the S‐vacancy‐mediated regulation of CO 2 RR performance in the 2D SnS 2 ‐based catalysts and provide valuable experimental guidance for the rational design of high‐performance HCOOH‐selective CO 2 RR catalysts.
