J Phys Chem A [JOURNAL]
Sun
200 papers
Frozen Natural Orbital-Based Extended Second-Order Algebraic Diagrammatic Construction for Core Ionization: Theory, Implementation, and Benchmark.
Majee K, Mukhopadhyay T, Manna A … +2 more , Izsák R, Dutta AK
J Phys Chem A · 2026 Jun · PMID 42227883 · Publisher ↗
We have developed a low-cost method using the extended version of the second-order algebraic diagrammatic construction method for core-ionization potential calculations (IP-ADC(2)-x). The efficiency of the method is enha...
We have developed a low-cost method using the extended version of the second-order algebraic diagrammatic construction method for core-ionization potential calculations (IP-ADC(2)-x). The efficiency of the method is enhanced by the incorporation of frozen natural orbitals (FNOs) and natural auxiliary functions (NAFs) in combination with the core-valence separation (CVS) and density fitting (DF) approximations. This approach balances computational efficiency and precision remarkably well. Employing natural orbitals significantly reduces the size of the virtual space while maintaining a systematically controlled accuracy, delivering a substantial speed-up compared to the standard method. Furthermore, the error due to the truncation of the virtual orbital space can be reduced by adding a simple correction to the FNO-IP-ADC(2)-x results. The overall accuracy of the method is governed by setting up FNO and NAF thresholds. The use of the spin-free exact two-component Hamiltonian (SFX2C1e) improves the agreement with experimental values. We have also investigated the use of projector-based embedding theory to calculate core-ionization potentials for large molecules. Using the embedded FNO-IP-ADC(2)-x method, we have successfully computed the core-ionization energies of N-doped fullerene (azafullerene) and chlorophyll-a molecules, with approximately 2600 and 4000 basis functions, respectively, with an impressive speed-up.
Benchmarking the UMA Foundation Interatomic Potential for Gas-Phase Chemical Kinetics.
Kendall DT, Zádor J
J Phys Chem A · 2026 Jun · PMID 42223953 · Publisher ↗
Foundation machine-learned interatomic potentials promise rapid access to high-quality potential energy surfaces, but their fitness for gas-phase chemical kinetics remains largely untested. Here we benchmark the Universa...
Foundation machine-learned interatomic potentials promise rapid access to high-quality potential energy surfaces, but their fitness for gas-phase chemical kinetics remains largely untested. Here we benchmark the Universal Models for Atoms (UMA) foundation model for gas-phase kinetics applications relevant to combustion and atmospheric chemistry using our automated KinBot workflow across 12 representative systems. We compare optimized structures and ZPE-corrected energetics against the parent level of theory, ωB97M-V/def2-TZVPD, and assess pathway discovery, stationary-point fidelity, and downstream kinetic inputs such as conformer ordering and one-dimensional hindered rotor scans. UMA reliably identifies the expected reaction channels over broad regions of chemical space, including pathways that are also a challenge for ab initio methods. Single-point DFT corrections at UMA geometries are an efficient way to improve energies. Overall, we suggest a practical hybrid workflow in which UMA performs inexpensive exploration and sampling, while DFT refinement is reserved for the important regions of the PES. Our results indicate that UMA can substantially accelerate rate coefficient calculations for gas-phase systems, motivating future work on uncertainty quantification, targeted finetuning, and Δ-learning corrections toward a gas-phase kinetics-specialized foundation model.
Photobleaching of Imidazole Brown Carbon in Single Levitated Aerosol Particles.
Zhang X, Meehan PE, Knight JW … +2 more , Orr-Ewing AJ, Cotterell MI
J Phys Chem A · 2026 Jun · PMID 42223447 · Full text
Brown carbon (BrC) aerosols are key contributors to atmospheric light absorption and photochemistry, yet their optical properties and photochemical behavior are poorly understood. To explore the influence of a microdropl...
Brown carbon (BrC) aerosols are key contributors to atmospheric light absorption and photochemistry, yet their optical properties and photochemical behavior are poorly understood. To explore the influence of a microdroplet environment on the photochemical decay of a representative BrC species, single particle cavity ring-down spectroscopy was used to probe individual aerosol particles containing imidazole-2-carboxaldehyde (IC) confined inside a linear electrodynamic quadrupole balance. The aerosol particles were levitated and exposed to 405 nm wavelength laser light to drive photobleaching. The imaginary component of the complex refractive index () provided a direct characterization of the aerosol particle light absorption and was determined for varying exposures to the photolyzing light. The determined values decayed exponentially with exposure time, demonstrating photobleaching. A kinetic model incorporating Lorenz-Mie theory was fitted to the observed decay to obtain a photobleaching quantum yield (within the framework of the kinetic model) for IC of (9.6 ± 3.0) × 10. The developed kinetic framework can be used to predict photobleaching time scales in aerosols from knowledge of these effective quantum yields. Additional photobleaching measurements on bulk IC-containing solutions showed that the photobleaching quantum yields are an order of magnitude larger in aerosol droplets, potential reasons for which are discussed.
Explicitly Correlated Multireference Configuration Interaction Investigation of the Structures and Energetics of AlN (x ≥ 1, y ≥ 1, and x + y ≤ 4; q = 0-2) Nanoclusters.
Tekili A, Kamalakannan S, Gloriod A … +2 more , Abdelli-Messaci S, Hochlaf M
J Phys Chem A · 2026 Jun · PMID 42222934 · Publisher ↗
Aluminum nitride nanoclusters play a crucial role in materials science, astrophysics, and plasma physics. We study the AlN (x ≥ 1, y ≥ 1 and x + y ≤ 4; q = 0-2) species, for which we determine equilibrium structures, ene...
Aluminum nitride nanoclusters play a crucial role in materials science, astrophysics, and plasma physics. We study the AlN (x ≥ 1, y ≥ 1 and x + y ≤ 4; q = 0-2) species, for which we determine equilibrium structures, energies, harmonic frequencies, and dipole moments. Due to the pronounced multiconfigurational nature of some of their electronic wave functions, electronic structure calculations were performed using the explicitly correlated multireference configuration interaction method on top of full-active-space self-consistent field calculations. Several new forms were identified, notably for the tetratomics AlN, AlN and AlN and their cations. The current data should help to identify and characterize spectroscopically the AlN (x ≥ 1, y ≥ 1 and x + y ≤ 4; q = 0-2) species in astrophysical environments, in the laboratory, and in plasma, and to elucidate the chemical phenomena that occur during the growth of 2D and 3D aluminum nitride.
Infrared Spectra and Pressure-Dependent Yields of the Criegee Intermediate Methyl Vinyl Ketone Oxide and Its Iodoperoxy Adduct.
Hsu JY, Lee YP
J Phys Chem A · 2026 Jun · PMID 42220221 · Full text
Methyl vinyl ketone oxide (MVKO), a key Criegee intermediate from isoprene ozonolysis, is produced in laboratories via ultraviolet photolysis of 1,3-diiodo-but-2-ene [(CHI)HC═C(CH)I] in O. While the 3-iodo-3-peroxylbut-1...
Methyl vinyl ketone oxide (MVKO), a key Criegee intermediate from isoprene ozonolysis, is produced in laboratories via ultraviolet photolysis of 1,3-diiodo-but-2-ene [(CHI)HC═C(CH)I] in O. While the 3-iodo-3-peroxylbut-1-ene [CHC(CH)IOO, denoted IMVKO] adduct becomes stabilized at high pressures, the yield of MVKO decreases. We report the definitive infrared spectral identification of IMVKO, with seven observed bands showing excellent agreement with theoretical predictions. This observation also enables a more accurate MVKO spectrum, correcting prior reports that contained significant IMVKO contributions. By simultaneously monitoring IR bands of syn-MVKO and IMVKO, we quantified the pressure dependence of the syn-MVKO yield relative to the total of syn-MVKO and IMVKO, , to follow 1/ = (1.08 ± 0.11) + (1.08 ± 0.04)×10 [M]. Furthermore, incorporating quantum-chemically predicted IR intensities of MVKO and the loss of the precursor upon photolysis, the absolute yield () of MVKO was estimated as 1/ = (2.74 ± 0.40) + (3.00 ± 0.13) × 10 [M]. Possible reasons for MVKO's smaller yield than CHOO are discussed.
Chiroptics of In-Plane Excitons.
Sburlati S, Gustafson A, Kahr B
J Phys Chem A · 2026 Jun · PMID 42218668 · Full text
The exciton chirality method relates chiroptical activity to absolute stereochemistry, but because the procedure focuses on the geometry of coupled transition electric dipole moments only, the essential roles of magnetic...
The exciton chirality method relates chiroptical activity to absolute stereochemistry, but because the procedure focuses on the geometry of coupled transition electric dipole moments only, the essential roles of magnetic dipole and electric quadrupole transition moments are nonobvious in many applications. These moments become apparent when analyzing in-plane, achiral coupled excitons. In silico CH polyyne dimers spanning geometries between optically inactive H- and J-aggregate extrema are used to investigate the multipolar response of coupled excited states through the gyration and rotatory strength tensors. As anticipated, the chiroptical response is dominated by the exciton states. The responses are largest in some directions for intermediate geometries and can be reconciled simply with the transition moments derived from structure. The connection between the in-plane moments and the exciton chirality method is established by a minimal symmetry-breaking perturbation that generates circular dichroism couplets while preserving the electronic and pedagogic relationship to the planar systems.
IPSBrain: A Unified Intelligent Data Analysis Platform for Multimodal Experimental Characterization at Advanced Photon Source.
Pang Y, Li L, Deng X … +8 more , Xi Z, Li J, Han M, Sun Y, Yao H, Wu L, Yuan Q, Zhao L
J Phys Chem A · 2026 May · PMID 42214078 · Publisher ↗
Advanced photon sources deliver X-ray with unprecedented brilliance and coherence, facilitating sophisticated multimodal characterization of diverse materials while simultaneously generating data volumes that far exceed...
Advanced photon sources deliver X-ray with unprecedented brilliance and coherence, facilitating sophisticated multimodal characterization of diverse materials while simultaneously generating data volumes that far exceed the capacity of traditional, expert-driven analytical workflows. This growing gap between data acquisition and interpretation has become a critical bottleneck for timely scientific discovery, which creates a critical need for high-throughput and automated data analysis tools. Recent advances in artificial intelligence (AI) offer a transformative potential to address this challenge, enabling the direct mapping of complex experimental observations into scientific insights. However, existing AI-driven tools are remain largely fragmented and task-specific, limiting their adoption of modern multimodal experiments at the facility scale. Here we present IPSBrain, a unified AI-powered platform that serves as Intelligent Photon Source Brain for automated analysis of multimodal synchrotron experimental data. The platform integrated a series of novel, self-developed machine-learning-based models that enable automated data analysis from multiple experimental techniques, including diffraction, scattering, X-ray absorption, and tomograph. The platform is accessible through an intuitive web interface, which significantly lowers the technical barrier to advanced scientific data interpretation. By enabling end-to-end intelligent workflows from data acquisition to quantitative physical insight, IPSBrain supports high-throughput, reproducible, and scalable analysis aligned with the operational demands of modern synchrotron radiation sources. IPSBrain not only demonstrates a practical and extensible framework for AI-driven synchrotron data analysis but also establishes a transferable paradigm for intelligent data analysis of other large-scale research infrastructures, such as neutron sources and free-electron lasers.
Frontier Orbital Engineering in Heteroatom-Doped Prototypical Organic Dyes for Dye-Sensitized Solar Cells.
Singh A, Pandey RD, Jana S … +3 more , Samal P, Tecmer P, Ṡmiga S
J Phys Chem A · 2026 Jun · PMID 42213712 · Full text
The computational design of heteroatom-doped organic dyes for dye-sensitized solar cells (DSSCs) remains challenging, as predictive methods must accurately describe long-range charge-transfer (CT) excitations while remai...
The computational design of heteroatom-doped organic dyes for dye-sensitized solar cells (DSSCs) remains challenging, as predictive methods must accurately describe long-range charge-transfer (CT) excitations while remaining computationally efficient for systematic materials screening. In this work, we investigate the electronic structure and excited-state properties using the range-separated hybrid functional LC-ωPBE in conjunction with linear-response time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation (TDA). We employ a simplified, physically motivated, effective tuning protocol (ω) to enable the rapid and reliable screening of electronic properties of organic dyes. Charge-transfer excitation energies and frontier orbital alignment, the key factors governing light absorption and electron injection in DSSCs, are analyzed through targeted heteroatom (N, O, and B) incorporation into donor-π-acceptor (D-π-A) organic dyes. A library of 27 mono-, di-, and tridoped prototypical organic dyes is designed based on a carbazole donor and a cyanoacrylic acid acceptor through targeted doping at three positions of the π-bridge or linker. Distinct design trends emerge: electron-rich nitrogen and oxygen dopants increase the HOMO-LUMO gap and blue-shift CT excitations, with nitrogen exhibiting the strongest effect, whereas electron-deficient boron substitution narrows the gap and induces pronounced red shifts. Notably, the BBN-doped dye exhibits the smallest gap and lowest excitation energy, highlighting boron-rich motifs as promising candidates for enhanced solar light harvesting. Overall, this study establishes transferable heteroatom-doping guidelines and introduces an efficient, reliable, and cost-effective tuned DFT-TDDFT framework for high-throughput computational discovery and optimization of DSSC sensitizers.
The Visible Spectrum and Ionization Energy of Jet-Cooled Linear SiCCSi.
Flores J, Kaur D, Reilly NJ
J Phys Chem A · 2026 Jun · PMID 42213028 · Publisher ↗
The Σ ← Σ transition of linear SiCCSi has been examined in detail using resonant two-color two-photon ionization (R2C2PI), laser-induced fluorescence (LIF), and single-vibronic-level emission (SVLE) spectroscopy. Twenty-...
The Σ ← Σ transition of linear SiCCSi has been examined in detail using resonant two-color two-photon ionization (R2C2PI), laser-induced fluorescence (LIF), and single-vibronic-level emission (SVLE) spectroscopy. Twenty-three ground-state vibrational levels, including fundamental frequencies of totally symmetric modes and first overtones of IR-active nontotally symmetric modes, are assigned with confidence, providing a foundation for infrared laboratory surveys. In addition, a nearly complete assignment of the excitation spectrum, including many previously unidentified hot bands, has been made for transitions detectable by fluorescence. With the -state vibrationless level serving as the intermediate, we determine an adiabatic ionization energy (AIE) of 7.477(1) eV. B3LYP/aug-cc-pVQZ calculations give an AIE and ground-state vibrational frequencies in close accord with experiment but provide a relatively poor description of the -state, possibly because of a vibronic interaction with the close-lying state. The change in the Si-C bond length and rotational constant that we infer by fitting the Franck-Condon activity in the Si-C stretching mode is in excellent agreement with previous rotationally resolved analysis (both yielding /″ ∼ 0.966) but departs significantly from theory (/″ = 0.954); furthermore, the calculated -state Si-C stretch frequency is 25% too high. Measurement of the ← transition using 193 nm radiation (6.42 eV) for ionization results in remarkably different relative intensities for the same spectral features in comparison with LIF and near-threshold R2C2PI, as well as a relative insensitivity to the delay between resonant and ionizing photons. This difference is reconciled in terms of internal conversion from the -state to highly vibrationally excited levels of dark electronic states located ∼6.4 eV below the cation zero-point level, thereby admitting favorable overlap with commensurately vibrationally excited levels of the cation ground state at 193 nm.
A New Family of Seniority-Restricted Coupled Cluster Methods.
Lokhande R, de Moura CEV, Zsigmond K … +2 more , Ayers PW, Miranda-Quintana RA
J Phys Chem A · 2026 Jun · PMID 42210909 · Publisher ↗
We introduce a novel class of coupled cluster (CC) methods that leverage the seniority concept to enhance efficiency and accuracy in electronic structure calculations. While existing approaches, such as the pair coupled...
We introduce a novel class of coupled cluster (CC) methods that leverage the seniority concept to enhance efficiency and accuracy in electronic structure calculations. While existing approaches, such as the pair coupled cluster doubles (pCCD) method, are limited to seniority-zero (Ω = 0) wave functions, we propose a more flexible framework: seniority-restricted coupled cluster (sr-CC). This new methodology selectively constrains the seniority sectors accessible through excitation operators in the cluster expansion, enabling a more systematic exploration of electron correlation effects. By balancing computational cost and accuracy, sr-CC provides a promising pathway for advancing electronic structure theory, particularly in strongly correlated systems. We benchmark sr-CCSD(0), sr-CCSDTQ(0), and sr-CCSDT(2)Q(0) on BeH insertion, linear and cubic H, and F dissociation. The sr-CC hierarchy remains robust in strongly correlated regimes where conventional single-reference CC methods deteriorate. For H and F dissociation, sr-CCSDT(2)Q(0) and sr-CCSDTQ(0) reproduce FCI energies to near machine precision across the full dissociation range, while bypassing the need for orbital optimization, although intermediate geometries remain more demanding. Overall, excitation-rank-dependent seniority restrictions provide a systematically improvable strategy for extending coupled cluster theory into strongly correlated regimes within a unified exponential framework.
High-Resolution Spectroscopy and Theoretical Study of CO: Unveiling the 1A-X̃B Electronic Transition.
Li Y, Gu J, Lu H … +4 more , Liu W, Li Z, Chen Y, Zhao D
J Phys Chem A · 2026 Jun · PMID 42207610 · Publisher ↗
The vibronic spectrum of mass-selected CO in the 293-310 nm region has been recorded using photodissociation spectroscopy in combination with a cryogenic ion trap. We performed linearized pair-density functional theory (...
The vibronic spectrum of mass-selected CO in the 293-310 nm region has been recorded using photodissociation spectroscopy in combination with a cryogenic ion trap. We performed linearized pair-density functional theory (L-PDFT) calculations on potential energy surfaces of six lowest-lying electronic states to elucidate this spectrum. The results indicate that the six low-lying states originate from splitting of three degenerate Π states due to the Renner-Teller effect. Combined with the theoretical excitation energies, the spectrum corresponds to the dipole-allowed 1A-X̃B electronic transition. Calculations on the Franck-Condon factors and vibrational anharmonicity have yielded detailed assignments of the vibronic bands, revealing significant Fermi resonance between ν and 2ν vibronic levels. Partially resolved rotational features in the 0 band have also been analyzed to determine the accurate electronic transition energy. Bond order and spin density have been obtained by the analysis of multiconfigurational wave functions, providing a more in-depth understanding of the electronic structure and bonding characteristics of CO. This work highlights L-PDFT as a highly effective method for studying the excited states of open-shell molecules with strong electronic correlations.
The Concept of Meta-Accurate Parameters and Its Application to Molecular Structure.
Vishnevskiy YV
J Phys Chem A · 2026 Jun · PMID 42206923 · Publisher ↗
A new concept for the determination and representation of molecular parameters is introduced for the general case when experimental and theoretical data are used together in the refinement process. The meta-accurate para...
A new concept for the determination and representation of molecular parameters is introduced for the general case when experimental and theoretical data are used together in the refinement process. The meta-accurate parameters obtained in this way must fulfill particular criteria related to trueness, precision, and contribution of experimental data. The concept is applied to the field of molecular structure and demonstrated on a particular example. Using experimental rotational constants for arsenic trichloride (AsCl) available in the literature, together with the vibration-rotation interaction and electron-mass corrections theoretically predicted in this work, the equilibrium meta-accurate molecular structure (MAMS) parameters were determined by the method proposed here: (As-Cl) = 2.15838(3){61} Å and α(Cl-As-Cl) = 98.877(5){40} °, where the numbers in parentheses and curly braces represent accurate total standard deviations in units of the last digit and experimental data contributions in percent, respectively. Applications, advantages, and future perspectives of the concept are discussed.
Substituent and Matrix Effects in Electron-Induced One- and Two-Electron Reduction of Quinones.
Somani A, Sander W
J Phys Chem A · 2026 Jun · PMID 42202228 · Publisher ↗
The one- and two-electron reduction chemistry of -benzoquinone and tetrafluoro--benzoquinone (fluoranil) was investigated in argon and amorphous water ice matrices at cryogenic temperatures (3-9 K). Sodium atoms served...
The one- and two-electron reduction chemistry of -benzoquinone and tetrafluoro--benzoquinone (fluoranil) was investigated in argon and amorphous water ice matrices at cryogenic temperatures (3-9 K). Sodium atoms served as the electron source, and reaction products were characterized by matrix-isolation FTIR and UV-vis spectroscopy. In argon matrices, co-deposition of quinones with sodium vapor followed by visible-light excitation of matrix-isolated sodium atoms generated the corresponding radical anions. Photoexcitation of the -benzoquinone radical anion at 430 nm resulted in photoionization and regeneration of the parent quinone , whereas the fluoranil radical anion was photostable under identical conditions. In amorphous water ice, sodium atoms underwent spontaneous ionization to form hydrated electrons, which reacted with embedded quinones. -Benzoquinone yielded both the radical anion and the dianion , with subsequent photochemistry revealing a reversible interconversion between , , and . In contrast, fluoranil underwent preferential two-electron reduction to form the dianion , which also displayed further photochemical transformations analogous to those observed for -benzoquinone. These results highlight the pronounced substituent and matrix effects on low-temperature electron-transfer and photochemical behavior of quinones.
On the Equivalence of Two-Point Basis-Set Extrapolations and Robust Parameterization for Coupled-Cluster and Double-Hybrid DFT Methods.
Iron MA
J Phys Chem A · 2026 Jun · PMID 42202053 · Full text
Basis-set extrapolation (BSE) to the complete basis set (CBS) limit is a cornerstone of several high-accuracy thermochemical computational schemes. In this study, we assess some of the approximations that are commonly ma...
Basis-set extrapolation (BSE) to the complete basis set (CBS) limit is a cornerstone of several high-accuracy thermochemical computational schemes. In this study, we assess some of the approximations that are commonly made when using BSE. While the extrapolation parameters are typically fitted using coupled-cluster methods, there are cases where these same parameters are applied to other computational methods. While there can be significant differences in the fitted parameters, when applied to two benchmark datasets the difference in performance between the coupled-cluster and method-specific fitted parameters is small. While there are a number of schemes for two-basis-set extrapolations to the CBS limit, it is shown that three common extrapolations─exponential, exponential-square root, and inverse power─reduce to a Schwenke-style correction to the larger basis set of the scaled difference between two sequential basis sets ( = + ·( - )). Moreover, this reduction means that the differences between the methods is mathematically meaningless, and given the extrapolation parameter of one scheme one can find both the Schwenke-type extrapolation factor and the extrapolation factors of the other two schemes and vice versa. Finally, Schwenke-type two-point extrapolation parameters are given for a selection of basis sets for coupled-cluster and selected double-hybrid density functional theory exchange-correlation functionals.
Temperature-Dependent Kinetics of the Methyl Vinyl Ketone Oxide Criegee Intermediate: Self-Reaction and Reaction with Trifluoroacetic Acid.
Khodia S, Reilly E, Garavagno MLA … +1 more , Orr-Ewing AJ
J Phys Chem A · 2026 Jun · PMID 42200549 · Full text
Direct kinetic measurements are reported for the self-reaction and unimolecular decay of methyl vinyl ketone oxide (MVKOO), and its reactions with trifluoroacetic acid (TFA) and formic acid (FA). The -MVKOO stabilized Cr...
Direct kinetic measurements are reported for the self-reaction and unimolecular decay of methyl vinyl ketone oxide (MVKOO), and its reactions with trifluoroacetic acid (TFA) and formic acid (FA). The -MVKOO stabilized Criegee intermediate was generated by laser flash photolysis of 1,3-diiodobut-2-ene in excess O and monitored via its absorption at 360 nm using cavity ring-down spectroscopy. Time-resolved MVKOO decay traces recorded in the absence of added coreactants were analyzed to separate the first-order unimolecular thermal decomposition from second-order self-reaction contributions. Within the 270-330 K temperature and 40-200 Torr pressure ranges studied, MVKOO undergoes rapid second-order self-reaction with a rate coefficient = (12 ± 4) × 10 cm s that shows no significant temperature or pressure dependence. At 292 K, the unimolecular decay rate coefficient is = (50 ± 21) s, averaged over 40-200 Torr measurements, and shows a positive temperature dependence. Bimolecular reactions of MVKOO with FA and TFA were investigated under pseudo-first-order conditions, yielding rate coefficients of = (1.9 ± 0.2) × 10 cm s and = (3.8 ± 0.3) × 10 cm s at 292 K, respectively. The MVKOO + TFA reaction exhibits a weak negative temperature dependence. The measured rate coefficients for MVKOO reaction with FA and TFA are consistent with the predictions from a structure-activity relationship based on dipole-mediated interactions. These findings quantify key unimolecular and bimolecular loss processes of MVKOO and further highlight the potential atmospheric significance of Criegee intermediate-acid chemistry in organic oxidation pathways.
CB[5]@CB[10]. Dynamics and Interaction Energy Considerations in a Molecular Gyroscope from MD+EDA Calculations.
Paco-Chipana M, Muñoz-Castro A
J Phys Chem A · 2026 Jun · PMID 42200216 · Publisher ↗
Supramolecular noncovalent interactions infer flexibility desired to enable functional motion and molecular machinery, favoring the development of complex molecular machines at the nanoscale. Here, we evaluate the dynami...
Supramolecular noncovalent interactions infer flexibility desired to enable functional motion and molecular machinery, favoring the development of complex molecular machines at the nanoscale. Here, we evaluate the dynamical behavior of supramolecular gyroscane-like complexes, given by CB[5]@CB[10] and Cl@CB[5]@CB[10]. Our results denote that noncoaxial conformations are energetically favored due to reduced Pauli repulsion and enhanced electrostatic interactions, from a combined molecular dynamics (MD) simulations and energy decomposition analysis (EDA), denoted as MD+EDA approach, the intricate gyroscope-like rotational and precessional motions between the inner CB[5] unit and the outer CB[10] cavity are revealed, showing the impact of further incorporation of anions to modulating the supramolecular interaction dynamics. The MD+EDA approach elucidates fluctuating energy contributions during motion, showing that chloride inclusion buffers electrostatic stabilization and facilitates freer molecular motion. These findings advance understanding of noncovalent interactions governing dynamic supramolecular assemblies and provide foundational insights for designing artificial molecular machines with controllable, multifunctional motion.
Energetic Processing of Solid Nitrogen: Infrared Identification of N and Correlated γ-Line Emission under Electron Impact and Extreme-UV Irradiation.
Chou SL, Danny H, Lin SY … +3 more , Huang WJ, Chen YJ, Wu YJ
J Phys Chem A · 2026 Jun · PMID 42199030 · Publisher ↗
We investigate the energetic processing of solid N at 3 K under 300 eV electron impact and extreme-UV irradiation at 58.4 and 68.8 nm by combining in situ IR absorption spectroscopy with simultaneous UV-visible-near-IR l...
We investigate the energetic processing of solid N at 3 K under 300 eV electron impact and extreme-UV irradiation at 58.4 and 68.8 nm by combining in situ IR absorption spectroscopy with simultaneous UV-visible-near-IR luminescence measurements. Electron bombardment produces clear infrared signatures of N, N, and N, whereas extreme-UV irradiation predominantly yields neutral products, with N as the major nitrogen-bearing species and only weak N absorption. The accompanying emission spectra reveal the formation of excited N and N atoms under both excitation modes, together with a weak near-IR γ-line. Controlled warm-up of the electron-irradiated samples shows that the γ-line intensity increases sharply between 13 and 18 K, coincident with the most rapid decrease of the N infrared band, while the N absorption remains nearly unchanged. This correlated behavior is consistent with the γ-line emission being associated with a neutralization-driven relaxation pathway involving an N-related precursor, although the microscopic emitting state remains to be identified. Preliminary vacuum-ultraviolet photoionization mass spectrometry performed during desorption at 25 K further suggests that irradiated solid N contains metastable higher-order nitrogen reservoirs beyond simple N molecules. These results provide direct spectroscopic constraints on the formation, stabilization, and relaxation of metastable polynitrogen species in condensed nitrogen and show how irradiated solid N can transiently store and redistribute electronic energy through coupled radiative and nonradiative channels.
Enhancing Molecular High-Pressure Simulations by Implicit Solvation.
Kißing N, Zeller F, Neudecker T
J Phys Chem A · 2026 Jun · PMID 42190274 · Full text
Gaussians On Surface Tesserae Simulate HYdrostatic Pressure (GOSTSHYP) and the eXtended Hydrostatic Compression Force Field (X-HCFF) are quantum chemical methods to simulate the effects of pressure on a single molecule....
Gaussians On Surface Tesserae Simulate HYdrostatic Pressure (GOSTSHYP) and the eXtended Hydrostatic Compression Force Field (X-HCFF) are quantum chemical methods to simulate the effects of pressure on a single molecule. Both methods have the usage of discretized molecular surfaces in common, which are also needed in implicit solvation models like the Conductor-like Polarizable Continuum Model (C-PCM). However, a combined usage of GOSTSHYP or X-HCFF with C-PCM was not possible in previous implementations inside the Q-Chem program package. To address this circumstance, we present an independent surface construction routine for both of the pressure models. This routine enables a stable combination of C-PCM with GOSTSHYP or X-HCFF, which serves as the first step to consider the chemical surrounding inside these two pressure models. For three different compounds occurring in both neutral and zwitterionic forms, the energetic difference between these states under pressure via GOSTSHYP was investigated. Especially for compounds occurring in both zwitterionic and neutral structures, the C-PCM is essential to access the zwitterionic state. Calculated pressure dependencies in the Raman spectra of the zwitterionic structure of glycine show good agreement with experimental data. The dimerization reaction of orthosilicic acid at elevated pressure is also influenced by implicit solvation, leading to better agreement between the simulations and the experimental data. This study paves the way for the inclusion of explicit solvation to disentangle intra- and intermolecular effects that cause geometric and spectroscopic changes under pressure applied with GOSTSHYP and X-HCFF.
From Aromatic to Antiaromatic: Charge-Induced Electronic Transformation and Unexpected Stability of BNi.
Duong LV, Tam NM, Chwastyk M … +2 more , Pham LN, Nguyen MT
J Phys Chem A · 2026 Jun · PMID 42189763 · Publisher ↗
The structural and electronic features of BNi were examined across multiple charge states, revealing a double-ring configuration with three Ni atoms encapsulated within the B framework. symmetry is consistently favored,...
The structural and electronic features of BNi were examined across multiple charge states, revealing a double-ring configuration with three Ni atoms encapsulated within the B framework. symmetry is consistently favored, with the neutral and anionic species representing the global minima. Analyses of bond current strength and orbital interactions highlight the crucial role of the ψ(2 0 2) wave function in stabilizing the system through enhanced Ni-Ni and intraring B-B bonding. The transformation of ψ(2 0 2) into a ψ(3 3 1)-like character triggers rotational transitions, and the way these transitions are quenched becomes an intriguing story of this study. Born-Oppenheimer molecular dynamics simulations at 300-900 K and Δ calculations confirm the high thermodynamic stability of both the neutral and anionic species. The neutral BNi is more stable overall, whereas the anion BNi exhibits rotational motion of the boron framework around the nickel atoms, highlighting its potential as an antiaromaticity antifriction bearing motor at high temperatures.
Bridging Hydrocarbon Thermodynamics and Electron-Density Isosurfaces with Explainable Machine Learning.
Liu R, Wang L, Zhang X … +1 more , Li G
J Phys Chem A · 2026 Jun · PMID 42187288 · Publisher ↗
Key thermodynamic properties of hydrocarbons are essential for process design and for reliable thermodynamic modeling. Experimental measurements are often costly or unavailable for many compounds, and prediction models a...
Key thermodynamic properties of hydrocarbons are essential for process design and for reliable thermodynamic modeling. Experimental measurements are often costly or unavailable for many compounds, and prediction models are rarely further updated and optimized after the establishment of the classic thermodynamic estimation method. Here we develop compact and physically interpretable QSPR models that predict these properties from descriptors obtained by quantitative analysis of molecular surface defined on the 0.001 au electron-density isosurface. Molecular geometries and wave functions are generated using a baseline DFT protocol (B3LYP/6-31G(d,p) with harmonic frequency checks), and the robustness of the selected descriptor set is further examined across alternative functionals/basis sets and solvent-continuum settings. Using variance-inflation-factor (VIF) pruning to control multicollinearity, we combine sparse linear models (LASSO) with sure independence screening and sparsifying operator (SISSO) to obtain concise closed-form expressions (typically 1-2 composite descriptors). Across the corresponding test splits, all reported models achieve high predictive accuracy (test-set generally > 0.95), while retaining clear physical meaning: density-like packing proxy (/), geometric size/shape measures (, sphericity ), and, where needed, electrostatic-surface statistics (e.g., charge-balance ν, ESP skewness) jointly rationalize trends in volatility and critical behavior. The resulting formulas provide a practical bridge between first-principles electronic-structure calculations at the molecular scale and macroscopic thermodynamic properties, enabling rapid property estimation with transparent structure-property interpretation.
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