J Phys Chem A [JOURNAL]
Sun
200 papers
New Insights into Thermal Transport in ε-CL-20 Revealed by Machine-Learned Potentials and Mode-Projection Analysis.
Fang Y, Li W, Hang G … +5 more , Wang J, Yun X, Guo W, Wang T, Yu W
J Phys Chem A · 2026 Jun · PMID 42187253 · Publisher ↗
The thermal conductivity of energetic molecular crystals is a critical safety parameter, yet its temperature dependence remains poorly understood from a mode-resolved perspective. Here, we elucidate the underlying mechan...
The thermal conductivity of energetic molecular crystals is a critical safety parameter, yet its temperature dependence remains poorly understood from a mode-resolved perspective. Here, we elucidate the underlying mechanisms in ε-CL-20 by integrating a high-accuracy, machine-learned potential with comprehensive vibrational-dynamics analysis. Using transfer learning, we fine-tuned a neuroevolution potential that reproduces DFT-level accuracy. The anisotropic thermal conductivity, calculated with this potential, decreases significantly from 200 to 400 K. Spectral energy density analysis reveals that this decline originates from a universal shortening of phonon lifetimes and a crossover from particle-like propagation to wave-like tunneling. Full unit-cell mode-projection analysis demonstrates that temperature selectively strengthens anharmonic couplings between N-NO bending vibrations and cage-skeleton deformation modes. Nonequilibrium mode-excitation simulations further reveal that the cage-deformation mode acts as an energy-flux hub, directing thermal energy toward nitro-group vibrations, with a temperature-gated redistribution of dominant receiving channels. Crucially, the wave-like tunneling channels and the mode-mode coupling pathways are two manifestations of the same anharmonic network. The degradation of heat conduction and the funneling of energy toward reactive trigger bonds are therefore two sides of the same coin. Under rapid external loading, the inward flux overwhelms dissipative backflow, driving vibrational-amplitude growth and bond cleavage. This work provides phonon-resolved dynamic evidence directly linking macroscopic heat conduction to the microscopic initiation of chemical reactions and paves the way toward a general framework for investigating energy-flux networks in complex molecular solids.
Assessment of Excited-State Methods for One- and Two-Photon Absorption in the Retinal Protonated Schiff Base.
Di Prima D, Reinholdt P, Kongsted J
J Phys Chem A · 2026 Jun · PMID 42187015 · Publisher ↗
The retinal protonated Schiff base (rPSB) is the chromophore of rhodopsins, a family of light-sensitive proteins employed in optogenetics and biomedical research. Accurate computational prediction of its optical properti...
The retinal protonated Schiff base (rPSB) is the chromophore of rhodopsins, a family of light-sensitive proteins employed in optogenetics and biomedical research. Accurate computational prediction of its optical properties is essential for the in silico design of rhodopsin variants. While multiconfigurational methods are required to describe the photochemical isomerization of rPSB, the vertical absorption properties can be reliably assessed with more cost-effective electronic-structure approaches. In this work, we benchmark vertical excitation energies (Δ), oscillator strengths, and two-photon absorption (TPA) transition strengths (δ) for the S-S transition of rPSB across a representative sample of its configurational space. Results obtained with ISR-ADC(2), LR/QR-CC2, and range-separated TDDFT functionals are compared against EOM-EE-CCSD, with both the aug-cc-pVDZ and 6-31+G* basis sets. ISR-ADC(2) shows a strong correlation with EOM-EE-CCSD for all properties. LR/QR-CC2 exhibits lower and less consistent agreement, particularly for δ. The considered TDDFT methods reproduce excitation energies and oscillator strengths with excellent accuracy, although standard CAM-B3LYP slightly underperforms relative to other functionals. For TPA strengths, functionals with appropriate long-range exchange corrections display good correlation with EOM-EE-CCSD but systematically underestimates absolute values by approximately a factor of 4. It is indicated how to tune the exchange parameters of DFT functionals in order to adhere more to EOM-EE-CCSD or LR/QR-CC2 results.
Theoretical Exploration of Electronic and Second-Order Nonlinear Optical Properties of Superalkali-(Superhalogen Endohedral) Fullerene Complexes: Ta@Si-C and Ta@Si-BO@C.
Hou N, Yang Y, Wang ZY
J Phys Chem A · 2026 Jun · PMID 42186958 · Publisher ↗
To develop novel high-performance deep-ultraviolet (deep-UV) nonlinear optical (NLO) materials, two series of complexes (Ta@Si-C and Ta@Si-BO@C) were designed by integrating the superalkali Ta@Si, C fullerenes, and the s...
To develop novel high-performance deep-ultraviolet (deep-UV) nonlinear optical (NLO) materials, two series of complexes (Ta@Si-C and Ta@Si-BO@C) were designed by integrating the superalkali Ta@Si, C fullerenes, and the superhalogen BO. The results indicate that all complexes possess high structural stability, as reflected by significantly negative interaction energies. Compared to Ta@Si-C, the corresponding Ta@Si-BO@C complexes exhibit significant enhancements in both linear and nonlinear optical properties, which are reflected by their isotropic polarizabilities and first hyperpolarizabilities, respectively. Taking the most stable systems ( for Ta@Si-C; , and for Ta@Si-BO@C) as representative cases, the spatial contribution and structural origin of the hyperpolarizability were clarified through analyses of hyperpolarizability tensor and hyperpolarizability density, respectively. Molecular orbital and hole-electron analyses of crucial excited states further deepen the understanding of the electronic excitation nature of these key complexes. UV-vis absorption spectra confirm that all complexes have a deep-UV transparent region (≤200 nm), highlighting their potential as new deep-UV NLO molecular candidates. This work provides valuable insights for the rational design of high-performance deep-UV NLO materials based on superatom-based complexes.
Synergistic Regulation of Water Activity on the Polymorphs and Crystal Morphology of Ampicillin Sodium.
Zhang M, Wang N, Gao R … +4 more , Huang X, Wang T, Zhu D, Hao H
J Phys Chem A · 2026 Jun · PMID 42178786 · Publisher ↗
In this work, the synergistic mechanism by which water activity regulates the polymorphic transformation and crystal habit of ampicillin sodium crystals was elucidated, and the crystal structure of form D was determined....
In this work, the synergistic mechanism by which water activity regulates the polymorphic transformation and crystal habit of ampicillin sodium crystals was elucidated, and the crystal structure of form D was determined. Water activity was calculated based on the NRTL equation to determine the critical range for polymorphic transformation. Online Raman spectroscopy, PXRD, FTIR, molecular dynamics simulation, and other techniques were used in combination to reveal the effects of solvent composition, solid content, and temperature on the polymorphic transformation process and crystal habit. It was found that anhydrous form B with aggregated morphology is formed at low water activity, while the crystals transform into form D at high water activity, exhibiting improved dispersibility and a large, flake-like morphology. Increasing water activity could enhance solvent adsorption on various crystal faces, weaken intermolecular aggregation of the solute, and then result in crystals with improved dispersibility and flake-like morphology. By regulating the interactions between solvent molecules and crystal faces, water activity achieves the coordinated transformation of ampicillin sodium polymorphism and crystal habit, providing a reliable theoretical basis for the optimization of crystal forms and morphologies of β-lactam antibiotics.
Benchmarking Nanoscale Noncovalent Complexes at the Two-Hundred-Atom Scale with Converged Local CCSD(T).
Lao KU
J Phys Chem A · 2026 Jun · PMID 42175922 · Full text
We present vL27, a benchmark data set of 27 large noncovalent complexes with sizes up to 205 atoms, designed to probe nanoscale interaction effects. Reference binding energies were computed using local coupled cluster wi...
We present vL27, a benchmark data set of 27 large noncovalent complexes with sizes up to 205 atoms, designed to probe nanoscale interaction effects. Reference binding energies were computed using local coupled cluster with single, double, and perturbative triple [CCSD(T)] extrapolated to the complete basis set (CBS) limit with VeryTightPNO thresholds and complete pair natural orbital space (CPS) extrapolation to minimize errors arising from local approximations. The MP2/CBS scheme was validated against MP2-F12, and the local CCSD(T)/CPS protocol was benchmarked against canonical CCSD(T), confirming the robustness of both CBS and CPS extrapolation strategies for nanoscale systems. Symmetry-adapted perturbation theory (SAPT) analysis reveals that most complexes are dispersion-dominated or exhibit mixed interaction character, even for hydrogen-bonded systems lacking π-π stacking, underscoring the central role of dispersion and many-body effects in stabilizing large assemblies. Using these benchmark data, we evaluate a broad range of electronic structure methods, semiempirical approaches, and machine learning potentials. MP2+D3-ML, B97M-D4, ωB97M-D4, and HF-3c offer the best balance of accuracy and transferability, consistently reproducing both absolute interaction energies and relative binding trends. The vL27 data set thus provides a rigorous and chemically realistic foundation for evaluating and guiding the development of computationally efficient methods for nanoscale noncovalent systems.
Spatial Mapping of Valence Excited-State Landscapes Using Time-Resolved Shake-Down Spectroscopy.
Thompson HJ, Devetta M, Faccialà D … +22 more , Ingle RA, Pratt ST, Razmus WO, Vozzi C, Allum F, Ashfold MNR, Coriani S, Feifel R, Forbes R, Holland DMP, Rolles D, Squibb RJ, Bonanomi M, Callegari C, Coreno M, Danailov M, Demidovich A, Di Fraia M, Grazioli C, Manfredda M, Plekan O, Minns RS
J Phys Chem A · 2026 Jun · PMID 42172042 · Full text
Time-resolved X-ray photoelectron spectroscopy (XPS) is used to track the photodissociation dynamics of 2-iodothiophene following 262 nm excitation. The transient XPS features include both direct ionization of the initia...
Time-resolved X-ray photoelectron spectroscopy (XPS) is used to track the photodissociation dynamics of 2-iodothiophene following 262 nm excitation. The transient XPS features include both direct ionization of the initially populated excited states and pronounced satellite peaks arising from shake-down processes. While the direct ionization signals exhibit only minimal energy shifts during C-I bond cleavage, the shake-down transitions undergo a substantial, 5 eV, shift over the reaction coordinate. By correlating these shifts with simulated C-I bond lengths, a direct structural mapping is established that reveals the exceptional sensitivity of shake-down channels to molecular geometry. These results demonstrate that shake-down transitions provide a new and powerful probe of ultrafast structural dynamics.
Toward an Affordable Density-Based Measure for the Quality of a Coupled Cluster Calculation.
Jones GH, Weflen KE, Martin JML
J Phys Chem A · 2026 Jun · PMID 42170937 · Full text
We propose two new diagnostics for the degree to which static correlation impacts the quality of a coupled cluster calculation. The first is the change in the Matito static correlation diagnostic between CCSD and CCSD(T...
We propose two new diagnostics for the degree to which static correlation impacts the quality of a coupled cluster calculation. The first is the change in the Matito static correlation diagnostic between CCSD and CCSD(T), . The second is the ratio of the same and of the corresponding change in the total correlation diagnostic , i.e., . The first diagnostic can be extended to higher-order improvements in the wave function, e.g., . In general, a small [level] value indicates that at this level of theory, the density is converged and any further changes to the energy come from dynamical correlation, while larger [level] indicates that the density is still not converged at level and some static correlation remains. [()] is found to be a moderately good predictor for the importance of post-CCSD(T) correlation effects.
Toward Generalizable Surrogate Models for Molecular Dynamics via Graph Neural Networks.
Immanuel J, Mahata A, Maiti A
J Phys Chem A · 2026 Jun · PMID 42161483 · Publisher ↗
We present a graph neural network (GNN) based surrogate framework for molecular dynamics simulations that directly predicts atomic displacements and learns the underlying evolution operator of an atomistic system. Unlike...
We present a graph neural network (GNN) based surrogate framework for molecular dynamics simulations that directly predicts atomic displacements and learns the underlying evolution operator of an atomistic system. Unlike conventional molecular dynamics, which relies on repeated force evaluations and numerical time integration, the proposed surrogate model propagates atomic configurations forward in time without explicit force computation and can be applied in an autoregressive manner for multistep temporal evolution. The approach represents atomic environments as graphs and combines message-passing layers with attention mechanisms to capture local coordination and many-body interactions in metallic systems. Trained on classical molecular dynamics trajectories of bulk aluminum, the surrogate achieves sub angstrom level accuracy within the training horizon and exhibits stable behavior during short to midhorizon temporal extrapolation. Structural and dynamical fidelity are validated through agreement with reference radial distribution functions and mean squared displacement trends. The results suggests the model preserves key physical signatures beyond point-wise coordinate accuracy. The results from both the baseline single-step model and the autoregressive model establish that GNN-based surrogate integrators are a promising and computationally efficient complement to traditional molecular dynamics for accelerated atomistic simulations within validated settings.
Mechanism, Thermochemistry, and Kinetics for the CH + N Reaction Leading to Prompt NO Formation in Combustion.
Nguyen TL, Thorpe JH, Franke PR … +6 more , Jones GH, Peeters J, Bross DH, Ruscic B, Ellison GB, Stanton JF
J Phys Chem A · 2026 Jun · PMID 42160658 · Publisher ↗
The reaction of CH + N forming H + NCN is a remarkable example of activation of the nitrogen triple bond and is an important source of prompt NO in combustion. The reaction pathway is complex and proceeds through two com...
The reaction of CH + N forming H + NCN is a remarkable example of activation of the nitrogen triple bond and is an important source of prompt NO in combustion. The reaction pathway is complex and proceeds through two competing mechanisms: a cyclic addition channel initiated by c-HC(NN) and a chain-addition channel initiated by HCNN, both of which eventually form HNCN prior to dissociation to H + NCN. This work reinvestigates this reaction with composite coupled cluster protocols, including a novel spin-flip equation of motion coupled cluster scheme, combined with pragmatic two-dimensional master equation simulations of the resulting rate coefficients. These improved calculations predict the CH + N rate coefficient between the two more recent previous theoretical results and reduce the uncertainties of the best theoretical models of this reaction to less than a factor of 1.3. Additionally, we provide a closer theoretical investigation of the simultaneous dependence of the CH + N rate coefficient on pressure and temperature, and affirm that collisionally stabilized HNCN, another potential source of prompt NO, emerges as an appreciable product of this reaction under conditions relevant to automotive internal combustion engines and aircraft gas turbine engines.
How an Equi-Ensemble Description Systematically Outperforms the Weighted Ensemble Variational Quantum Eigensolver.
Rajamani A, Beseda M, Lasorne B … +1 more , Senjean B
J Phys Chem A · 2026 Jun · PMID 42160615 · Publisher ↗
Calculating excited states in chemistry is crucial to providing insight into photoinduced molecular behavior beyond the ground state, enabling innovations in spectroscopy, material sciences, and drug design. While severa...
Calculating excited states in chemistry is crucial to providing insight into photoinduced molecular behavior beyond the ground state, enabling innovations in spectroscopy, material sciences, and drug design. While several approaches have been developed to compute excited-state properties, finding the best ratio between the computational cost and accuracy remains challenging. The advent of quantum computers brings new perspectives with the development of quantum algorithms that promise an advantage over classical ones. Most of these new algorithms are inspired by previous classical ones but with different pros and cons. In this work, we focus on the choice of the weights within the ensemble variational quantum eigensolver (VQE) based on the generalization of the variational principle for many-body excited states. We compare the performance of the equi-ensemble and weighted ensemble VQE on two types of problems that cover different correlation regimes: (1) the many-body electronic structure problem of formaldimine using the generalized unitary coupled cluster ansatz and (2) the one-body noninteracting Kohn-Sham problem of hydrogen chains using the RCNOT hardware-efficient ansatz. While the equi-ensemble objective is to perform a block-diagonalization only, the weighted ensemble has the additional complexity to reach the targeted eigenstates and eigenvalues. In this work, we show that such a difference leads to several significant consequences, such as the increase in circuit depth together with optimization issues. We conclude that one should always favor the use of equi-weights, even if it requires an additional postprocessing step to extract the eigenvalues of the problem.
On the Performance of QTP Functionals Applied to Second-Order Response Properties II: Dynamic Polarizability and Long-Range C Coefficients.
Mendes RA, Franke PR, Perera A … +1 more , Bartlett RJ
J Phys Chem A · 2026 Jun · PMID 42160205 · Publisher ↗
This work is the second in the series "On the performance of QTP functionals applied to second-order response properties." In the first paper ( , , 054105), we demonstrated the good performance of Quantum Theory Project...
This work is the second in the series "On the performance of QTP functionals applied to second-order response properties." In the first paper ( , , 054105), we demonstrated the good performance of Quantum Theory Project functionals in predicting static perturbed second-order properties, such as static polarizabilities, nuclear magnetic resonance (NMR) spin-spin coupling constants, and NMR chemical shifts. In the present study, we focus on frequency-dependent properties, namely dynamic polarizabilities and dispersion coefficients. For completeness, a total of 25 exchange-correlation (XC) functionals were investigated. Dynamic polarizabilities were evaluated at five different perturbation wavelengths: 632.99, 594.10, 543.52, 514.50, and 325.13 nm. This property was also computed using HF, LR-CC3, and EOM-CCSD. In general, EOM-CCSD results are very close to those obtained with linear-response CC3, except at the highest frequency. Among Kohn-Sham calculations, TPSS0 and QTP01 showed the best overall performance for dynamic polarizabilities. We also assessed how well QTP functionals reproduce the pole structure of the CO molecule. For the dispersion coefficients, calculations were performed using the Casimir-Polder equation. The best overall performance was obtained with O3LYP; however, the first 11 ranked functionals show very similar accuracy. Within the QTP family, QTP01 and LC-QTP provide the best results for coefficients.
DFT Study on the Mechanism of Isoprene Polymerization Catalyzed by Ziegler-Natta Catalyst with Esters and Diethers.
Sui K, Liu J, Chen J … +3 more , Zhou R, He A, Yang X
J Phys Chem A · 2026 Jun · PMID 42159405 · Publisher ↗
The internal electron donor is a crucial component of modern Ziegler-Natta catalysts. In this manuscript, we investigated the adsorption behavior of dimethyl phthalate (DMP), dimethyl 2,3-dimethylsuccinate (DMS), and 2,2...
The internal electron donor is a crucial component of modern Ziegler-Natta catalysts. In this manuscript, we investigated the adsorption behavior of dimethyl phthalate (DMP), dimethyl 2,3-dimethylsuccinate (DMS), and 2,2-dimethyl-1,3-dimethoxypropane (DMMP) on the multisite titanium active center model named TMC-2, as well as the coordination and insertion processes of isoprene using density functional theory (DFT). Among the models, the DMS chelating adsorption configuration (TMC-2*) exhibited the lowest reaction energy barrier (ΔG = 31.2 kcal/mol) and the highest stereoselectivity (ΔGstereo = 9.2 kcal/mol) during isoprene polymerization. In contrast, the adsorption of DMP and DMMP exerted only a marginal influence on both the geometric parameters of the active centers and the reaction energy barrier. In summary, the adsorption mode and type of internal electron donors significantly influence the coordination free energy and insertion energy barrier of isoprene. For the two insertion modes of isoprene, named re- and si- spatial configurations, the cis-1,4-re configuration presents the methyl substituents pointing to the right (clockwise when viewed down the C1-C4 axis), whereas the cis-1,4-si configuration presents them to the left (counterclockwise); this local chirality dictates which face can readily access the titanium center after donor adsorption. The reconfigured isoprene can spontaneously coordinate across all internal electron donor adsorption models, whereas the coordination process for the si configuration is strongly hindered.
Formation of Monocyclic and Polycyclic Hydrocarbons from Sequential Toluene Reactions in Coulomb Crystals.
Kocheril GS, Zagorec-Marks C, Allison SH … +1 more , Lewandowski HJ
J Phys Chem A · 2026 Jun · PMID 42155061 · Full text
Understanding the formation and reactivity of aromatic molecules is important for understanding chemistry in a wide range of environments, including the interstellar medium. The clear observation of polycyclic aromatic h...
Understanding the formation and reactivity of aromatic molecules is important for understanding chemistry in a wide range of environments, including the interstellar medium. The clear observation of polycyclic aromatic hydrocarbons (PAHs) in space has intensified efforts to identify efficient formation pathways capable of producing such complex species under cold, dilute conditions. In astrochemical environments, ion-molecule reactions are typically the dominant type of reactions due to their high efficiency compared to neutral-neutral reactions. However, current models of PAH formation largely neglect ion-molecule reactions beyond the initial formation of benzene. Here, we present results from a series of ion-molecule reactions carried out in Coulomb Crystals beginning with the protonation of toluene to identify possible reaction pathways that could lead to interstellar PAH growth. In this work, we observe the formation of monocyclic aromatic species, CH and CH, via the initial dissociative proton transfer to toluene. We also observe an associative proton transfer product, resulting in CH. We find the sequential reaction between CH and CH results in the formation of CH, CH, and CH, which provides the first experimental evidence of a possible interstellar formation mechanisms of polycyclic cations beginning with monocyclic precursors.
Surface Energy Modulation of NiO through In Situ Click-Cross-Linked Networks for Air-Processed Flexible Blue Perovskite Light-Emitting Diodes.
Liu X, Wu J, Li H … +10 more , Wang Y, Guo Y, Dong F, Wang C, Li Z, Li C, Capaz RB, Zhang M, Wang H, Wang H
J Phys Chem A · 2026 Jun · PMID 42154977 · Publisher ↗
Air-processed flexible blue perovskite light-emitting diodes (PeLEDs) are crucial for advancing flexible displays and wearable optoelectronic devices. However, the NiO functional layer in such a flexible device faces a c...
Air-processed flexible blue perovskite light-emitting diodes (PeLEDs) are crucial for advancing flexible displays and wearable optoelectronic devices. However, the NiO functional layer in such a flexible device faces a critical challenge of surface energy control within an extremely narrow polarity range to balance water resistance and perovskite precursor wettability. Herein, we demonstrate the postpolymerization modification strategy of click-cross-linking that in situ constructs polymer networks, which significantly improves the mechanical flexibility of the NiO film and the interfacial contact between NiO and perovskite. Furthermore, the polymer network precisely modulates the surface energy of the NiO film based on the selective hydrogen bond interaction between the polymer and solvent molecules (HO and DMSO). The flexible NiO film is capable of simultaneously achieving good DMSO wetting and HO resistance, which facilitates the perovskite film fabrication under ambient conditions. Consequently, we realize the first air-processed flexible blue PeLEDs, achieving a peak external quantum efficiency (EQE) of 1.32% with exceptional bending durability, retaining over 80% of the initial EQE after 2000 bending cycles. This work offers a guideline for surface energy modulation to achieve a robust flexible inorganic hole transport layer for air-processed blue perovskite fabrication, opening an avenue for advancing flexible perovskite displays.
Intramolecular Vibrational Energy Transfer in the Precatalyst [Mn(ppy)(CO)] Tracked by Dual-Frequency 2D Infrared Spectroscopy.
Flesch S, Procacci B, Gurung S … +4 more , Choudhary S, Fairlamb IJS, Lynam JM, Hunt NT
J Phys Chem A · 2026 May · PMID 42150131 · Full text
The thermal dissociation of carbon monoxide is a fundamental entry step to many catalytic cycles involving metal carbonyl (MCO) complexes as it reveals a vacant coordination site at the metal center, enabling substrate c...
The thermal dissociation of carbon monoxide is a fundamental entry step to many catalytic cycles involving metal carbonyl (MCO) complexes as it reveals a vacant coordination site at the metal center, enabling substrate coordination. Overcoming the dissociation barrier requires sufficient accumulation of energy in vibrational modes with displacement vectors along the reaction coordinate (M-CO distance). Hence, understanding the energy transfer to and from these vibrations is essential in developing a detailed understanding of a precatalyst's activation pathway. Here, the intramolecular vibrational energy redistribution (IVR) within the heteroleptic metal carbonyl complex [Mn(ppy)(CO)] (, ppy = cyclometalated 2-phenylpyridine) in dichloromethane solution has been studied using dual-frequency, two-dimensional infrared spectroscopy. The responses of three vibrational modes localized on the ppy-ligand were monitored following the photoexcitation of carbonyl ligand stretching modes. A rise of signal strength by a factor of 4.7 within the first 35 ps, followed by a decay within ca. 150 ps exemplify the IVR from the metal carbonyl to the organic moiety, and the intermolecular energy transfer (IET) to the solvent, respectively. Moreover, pronounced changes of the spectral shape within the first 10 ps indicate the population of distinct vibrationally excited states. Direct anharmonic coupling between the pumped and probed modes gives rise to the initial spectral features, which include an uncommon, negative anharmonic coupling. These features do not decay single-exponentially as expected, but rise during the first 23 ps instead. This finding is assigned to the population of low-frequency modes (<250 cm), which are predicted to have a similar coupling pattern toward the measured bands as the CO stretching modes, based on density functional theory (DFT) calculations. The stronger signals predominant at late waiting times have uniform anharmonic shifts of ca. -2.5 cm arising from the coupling to medium-frequency modes (250-1200 cm), which are strongly localized on the ppy-ligand. Due to the distinct signal positions, the time-dependent populations of low- and medium-frequency modes can be evaluated independently. Rate constants for the rise of their populations were found to be 1/52 ps and 1/58 ps, respectively, while the rate constants of depopulation via IET to the solvent are 1/19 ps and 1/25 ps.
Robust Performance of the Noniterative Triples Corrections in CCSD(T): YbS as a Challenging Case with Strong Variation of Orbital Rotation.
Chen T, Changala PB, McCarthy MC … +1 more , Cheng L
J Phys Chem A · 2026 May · PMID 42150127 · Publisher ↗
A relativistic coupled-cluster study on the ytterbium monosulfide molecule (YbS) in synergy with a high resolution microwave spectroscopy study is reported. The quality of the potential energy surfaces and the surfaces o...
A relativistic coupled-cluster study on the ytterbium monosulfide molecule (YbS) in synergy with a high resolution microwave spectroscopy study is reported. The quality of the potential energy surfaces and the surfaces of the nuclear electric quadrupole coupling constants ('s) computed using relativistic exact two-component (X2C) coupled-cluster singles and doubles (CCSD), CCSD augmented with a noniterative treatment of triple excitations [CCSD(T)], and the "Λ"-version of CCSD(T) [CCSD(T)] is carefully assessed, comparing computed structure parameters and values to precise experimental benchmark values derived from the microwave rotational spectrum of vibrationally excited YbS. The X2C-CCSD calculations are shown to provide qualitatively accurate results, while CCSD(T) calculations provide reliable triples corrections. The inaccuracy of the corresponding CCSD(T) calculations is attributed to a strong variation of orbital rotation due to the coupling between the Yb[4f6s]S[2s2p] and Yb[4f6s]S[2s2p] configurations along the potential energy surface.
Gas-Phase Far-Infrared and Rotational Spectroscopy of 1- and 2-Cyanonaphthalene: Experiment and Theory.
Bentley MR, Franke PR, Esselman BJ … +3 more , Voute A, Jacovella U, Martin-Drumel MA
J Phys Chem A · 2026 May · PMID 42149906 · Publisher ↗
Cyanonaphthalenes (CHCN) are bicyclic, nitrogen-substituted polycyclic aromatic hydrocarbons and the first polycyclic species detected in the interstellar medium via radioastronomy. Here, we report a combined experimenta...
Cyanonaphthalenes (CHCN) are bicyclic, nitrogen-substituted polycyclic aromatic hydrocarbons and the first polycyclic species detected in the interstellar medium via radioastronomy. Here, we report a combined experimental and computational study of 1- and 2-cyanonaphthalene, extending and improving the spectroscopic characterization of their rotational and vibrational spectra. Gas-phase far-infrared vibrational spectra were measured in the 50-650 cm region with a Fourier-transform infrared spectrometer, providing the first gas-phase experimental vibrational band centers for these molecules. Pure rotational spectra were recorded between 75 and 220 GHz using chirped-pulse Fourier-transform and source-frequency-modulation spectroscopy, enabling extended observation of transitions in the ground vibrational states as well as the first spectroscopic characterization of low-lying vibrational states of energies lower than 200 cm. While density functional theory calculations guided initial spectral assignments, high-level coupled cluster computations were also performed and compared with experiment, yielding highly accurate fundamental vibrational frequencies and rotational constants for both ground and excited vibrational states.
Ultrafast Energy Transfer in Orthogonal Heptamethine Cyanine-Naphthalimide Systems: A Pathway toward High-Energy Excitation.
Jamjah A, Kölbel J, Mohammadpour P … +5 more , Raeesi AM, Honarvar Y, Nozary H, Jamali S, Fernández-Terán RJ
J Phys Chem A · 2026 Jun · PMID 42133939 · Publisher ↗
We report the synthesis and photophysical characterization of a family of bichromophoric systems, in which substituted naphthalimides (NMI) are covalently attached at the position of heptamethine cyanines (Cy7). Single...
We report the synthesis and photophysical characterization of a family of bichromophoric systems, in which substituted naphthalimides (NMI) are covalently attached at the position of heptamethine cyanines (Cy7). Single crystal X-ray diffraction and DFT calculations reveal a near-perpendicular arrangement of the NMI and Cy7 moieties, resulting in minimal electronic communication. Complementary variable-temperature NMR measurements reveal potential fluctuations in the dihedral angle between the two moieties. Steady-state spectroscopy and femtosecond transient absorption measurements reveal a non-negligible excited state coupling, linked to ultrafast internal conversion/energy transfer from an NMI localized high-lying excited state to the cyanine state. This process occurs on a subpicosecond time scale for all dyads, regardless of NMI substitution, leading to a large excitation-emission wavelength difference and an effective monochromophoric fluorescence behavior. Comparative studies with the NMI-pyridine precursors further highlight the role of intramolecular charge transfer in shaping the ultrafast dynamics in these systems, prior to cyanine attachment. Altogether, our results establish clear structure-property relationships for cyanine-based antenna constructs, thus providing design principles for multichromophoric systems that broaden cyanine absorption while preserving the integrity of the polymethine core.
Mechanistic Studies on the Reaction of HOClO with OH Radical on Aqueous Surfaces.
Xu F, Zhong J, Hadizadeh MH … +7 more , Hu Y, Yin Q, Zhang W, Tham YJ, An T, Francisco JS, Saiz-Lopez A
J Phys Chem A · 2026 May · PMID 42126996 · Publisher ↗
Chloric acid (HOClO) is a newly detected compound in the atmosphere and is involved in ozone depletion. The reaction of HOClO with OH radical is likely one of its main atmospheric loss processes. Aqueous surfaces have be...
Chloric acid (HOClO) is a newly detected compound in the atmosphere and is involved in ozone depletion. The reaction of HOClO with OH radical is likely one of its main atmospheric loss processes. Aqueous surfaces have been reported as critical media for reactions of some chlorine acids, such as HOCl/HCl. However, their effect on the reaction of HOClO with OH remains unexplored. Here, we use Born-Oppenheimer molecular dynamics simulations to investigate the reaction of HOClO with OH on an aqueous surface. The interfacial behaviors of the reactant (HOClO) and product (ClO) involved in this reaction were investigated. Gas phase HOClO can be absorbed on the aqueous surface by forming H-bonds between the acidic H atoms and water. As HOClO penetrates the sublayer, it rapidly dissociates into OClO and HO; however, before this dissociation, a competitive reaction with OH is likely due to the rapid reactivity of the radical. The reaction of HOClO with OH on the aqueous surface follows hydrogen abstraction mechanisms; these include the direct and water monomer/dimer-mediated abstraction pathways. Direct abstraction has no energy barrier and is most kinetically favored, compared to ∼0.5 kcal mol and ∼3.0 kcal mol for the water monomer- and dimer-mediated mechanisms, respectively. The resulting ClO can reside on the surface with its Cl atom exposed to the air, increasing the potential for further reactions with other atmospheric species. Overall, the specific reaction of HOClO with OH on the water surface, could lead to new chlorine recycling by converting HOClO into reactive species.
Selective Bond Breaking of HOD by Nonresonant Infrared Pulse Trains and a Delayed Ultraviolet Pulse.
Jing WQ, Sun ZP, Zhao SF … +1 more , Shu CC
J Phys Chem A · 2026 May · PMID 42124525 · Publisher ↗
Tailored ultrafast laser pulses provide a powerful means of selectively breaking bonds in polyatomic molecules. However, traditional laser control strategies often assume that reactions begin from pure eigenstates or the...
Tailored ultrafast laser pulses provide a powerful means of selectively breaking bonds in polyatomic molecules. However, traditional laser control strategies often assume that reactions begin from pure eigenstates or thermal ensembles. Here, we present a theoretical framework that combines an ultrashort infrared (IR) pulse train with a time-delayed ultraviolet (UV) pulse to achieve selective photodissociation in HOD─a prototypical system for mode-selective chemistry. Our approach utilizes nonresonant infrared (NIR) pulse trains to drive impulsive stimulated Raman scattering (ISRS), thereby generating coherent superpositions of the O-H and O-D stretching vibrational modes in the ground electronic state. These vibrational coherences enable UV-induced quantum interference: a time-delayed UV pulse projects the prepared vibrational states onto a repulsive electronic state, resulting in bond-selective photodissociation. By tuning the pulse delay and adjusting molecular orientation, we can steer the reaction pathway and, under optimal conditions, reduce the H/D product ratio to 0.3. Our findings underscore the critical roles of vibrational coherence and pulse shaping in controlling chemical reactivity and offer an analytically transparent perspective that connects vibrational-state preparation to dissociation branching ratios.
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