The Journal of Physical Chemistry A最新文献

{"title":"The Electronic Structure of Boron, Aluminum, and Scandium Monoxides: BO, AlO, and ScO","authors":"João Gabriel Farias Romeu,&nbsp;, ,&nbsp;James L. Gole,&nbsp;, and ,&nbsp;David A. Dixon*,&nbsp;","doi":"10.1021/acs.jpca.5c05513","DOIUrl":"10.1021/acs.jpca.5c05513","url":null,"abstract":"<p >The diatomics BO, AlO, and ScO play roles in the combustion of the parent atoms. Potential energy curves for the lowest-lying spin-free (ΛS) and spin–orbit (Ω) states of gas-phase BO, AlO, and ScO were calculated with the SA-CASSCF/SO-icMRCI+Q/aug-cc-pwCV<i>n</i>Z-DK method (<i>n</i> = Q for ScO and <i>n</i> = 5 for BO and AlO). The spectroscopic parameters obtained at the icMRCI+Q level are consistent with the available experimental data, and new data for the spin–orbit states are presented. At the CCSD(T) level, the use of reference PW91 orbitals resulted in a significant improvement of the spectroscopic parameters for AlO and small improvements for BO and ScO. The dissociation energies were predicted at the icMRCI+Q and Feller–Peterson–Dixon (FPD) levels, including CCSDT, CCSDTQ, and spin–orbit effects. For BO, AlO, and ScO, the FPD <i>D</i>₀ (<i>D</i>_e) values are 192.4 (195.1), 120.2 (121.6), and 158.2 (159.6) kcal/mol, respectively. NBO analysis shows that the ionic character increases in going from BO to AlO and slightly decreases in going from AlO to ScO, with two highly polarized π bonds and one σ bond. A pronounced multireference character is predicted for AlO at the CCSD(T) and SA-CASSCF/icMRCI+Q levels. The lowest excited states of BO and AlO are mostly formed from excitations on the 1π orbitals. For ScO, excitations on the 2σ orbital are the most significant to form the lowest excited states.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9368–9386"},"PeriodicalIF":2.8,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145172112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Absorption and Scattering Properties of Atmospheric Molecular Clusters","authors":"Georg Baadsgaard Trolle,&nbsp;, ,&nbsp;Jakub Kubečka,&nbsp;, and ,&nbsp;Jonas Elm*,&nbsp;","doi":"10.1021/acs.jpca.5c03658","DOIUrl":"10.1021/acs.jpca.5c03658","url":null,"abstract":"<p >Information about the optical properties of atmospheric molecular clusters is scarce as they are challenging to measure using current experimental techniques. Here we explore the absorption and Rayleigh scattering properties of acid–base molecular clusters using quantum chemical methods. We studied 127 small (acid)_1–2(base)_1–2 cluster systems, with the acids sulfuric acid (SA), methanesulfonic acid (MSA), nitric acid (NA), and formic acid (FA) in all combinations of the bases ammonia (AM), methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), and ethylenediamine (EDA). To further explore the effect of cluster size on the optical properties, we studied the large (SA)_<i>n</i>(AM)_<i>n</i> cluster systems, with <i>n</i> up to 15 acid–base pairs. We calculated the polarizability tensors and the 10 lowest excitation energies at the CAM-B3LYP/aug-cc-pVTZ level of theory. We find that the isotropic polarizability is almost linearly dependent on the cluster size, with small variations depending on the cluster composition. The anisotropic polarizability is plateauing as a function of cluster size. The larger the cluster, the more dominant the isotropic contribution becomes in the calculation of the Rayleigh light scattering activity. As a consequence, the Rayleigh scattering activity will increase quadratically as a function of cluster size. We stress that future studies on the scattering properties should be evaluated as effective scattering, taking the concentrations of the clusters into account. We find that the clusters absorb infrared (IR) radiation in the atmospheric spectral window region but speculate that their lifetime is too short to be competitive with common greenhouse gases. Due to the lack of strong chromophores in the studied acid–base clusters, the ultraviolet–visual (UV–vis) absorption is found to occur in the deep UV. Hence, clusters with more organic content should be studied in the future. Finally, we outline several directions in which the field of studying the optical properties of clusters and aerosols using response theory methods could evolve.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9129–9138"},"PeriodicalIF":2.8,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benchmarking Electronic-Structure Methods for the Description of Dark Transitions in Carbonyls at and Beyond the Franck–Condon Point","authors":"Jasmine Bone,&nbsp;, ,&nbsp;Javier Carmona-García,&nbsp;, ,&nbsp;Daniel Hollas*,&nbsp;, and ,&nbsp;Basile F. E. Curchod*,&nbsp;","doi":"10.1021/acs.jpca.5c05510","DOIUrl":"10.1021/acs.jpca.5c05510","url":null,"abstract":"<p >Herein, we propose a comprehensive benchmark of electronic-structure methods to describe dark transitions, that is, transitions to excited electronic states characterized by a near-zero oscillator strength. This type of electronic state is particularly important for the photochemistry of molecules containing carbonyl groups, such as atmospheric volatile organic compounds (VOCs). The oscillator strength characterizing a dark transition can change dramatically by a slight alteration of the molecular geometry around its ground-state equilibrium, the so-called non-Condon effects. Hence, testing the performance of electronic-structure methods for dark transitions requires considering molecules at their Franck–Condon point (i.e., equilibrium geometry), but also beyond the Franck–Condon point. Our benchmark focuses on various electronic-structure methods─LR-TDDFT(/TDA), ADC(2), CC2, EOM-CCSD, CC2/3, XMS-CASPT2─with CC3/aug-cc-pVTZ serving as a theoretical best estimate. These techniques are tested against a set of 16 carbonyl-containing VOCs at their equilibrium geometry. We then assess the performance of these methods to describe the dark transition of acetaldehyde beyond its Franck–Condon point by (i) distorting the molecule toward its S₁ minimum energy structure and (ii) sampling an approximate ground-state quantum distribution for the molecule and calculating photoabsorption cross-sections within the nuclear ensemble approach. Based on the calculated cross-sections, we calculate the photolysis half-life as depicted by the different electronic-structure methods─highlighting the impact of the different electronic-structure methods on predicted experimental photolysis observables. The observed inhomogeneities in the performance of certain methods in different regions of the potential energy surface, and their effect on the calculated observables, highlight the need to conduct analyses beyond the Franck–Condon point when benchmarking electronic-structure methods for describing excited states.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9355–9367"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c05510","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanistic Insights into Acid Generation from Nonionic Photoacid Generators for Extreme Ultraviolet and Electron Beam Lithography.","authors":"Chengbin Fu, Jie Xue, Hanshen Xin, Jianhua Zhang, Haoyuan Li","doi":"10.1021/acs.jpca.5c05089","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c05089","url":null,"abstract":"<p><p>Nonionic photoacid generators (PAGs) have emerged as key components in advanced extreme ultraviolet (EUV) and electron beam (EB) photoresists, offering advantages such as low dark loss, reduced outgassing, and suppressed phase separation. However, the lack of molecular-level understanding of their acid generation mechanisms hinders rational design and leads to reliance on trial-and-error synthesis. In this study, we perform a comprehensive density functional theory (DFT) investigation on 22 representative nonionic PAGs to elucidate their postexposure reaction pathways, encompassing bond dissociation, byproduct formation, and proton transfer mechanisms. Our findings reveal four distinct electron-triggered dissociation modes, including productive N-O/C-O bond cleavage and competing, nonproductive S-O bond cleavage. We identify the relative energy barrier between productive and unproductive pathways as a critical descriptor for photoacid generation efficiency and, by extension, photoresist sensitivity. Moreover, we demonstrate that molecular conformation (bent vs extended) and electron-withdrawing or electron-donating substituents profoundly impact the selectivity of bond dissociation. Importantly, this study also clarifies the roles of various proton sources (phenolic -OH⁺, t-BOC⁺ protecting groups, and intermediates during byproduct formation) in facilitating acid formation. Our analysis quantifies the energy barriers associated with each route, highlighting structure-dependent modulation of acid generation efficiency. These insights collectively establish a structure-mechanism-function relationship for nonionic PAGs and offer a predictive framework for designing next-generation high-sensitivity PAGs tailored for advanced lithographic applications.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benchmark Equilibrium Structures of Nucleobase Tautomers Validated Against Experimental Rotational Constants","authors":"Luca Di Fiore,&nbsp;, ,&nbsp;Luigi Crisci*,&nbsp;, ,&nbsp;Federico Lazzari,&nbsp;, ,&nbsp;Marco Mendolicchio,&nbsp;, and ,&nbsp;Vincenzo Barone*,&nbsp;","doi":"10.1021/acs.jpca.5c04369","DOIUrl":"10.1021/acs.jpca.5c04369","url":null,"abstract":"<p >Tautomerism in nucleobases is a subtle yet decisive factor in key biological processes, including mutagenesis, enzymatic catalysis, and molecular recognition. Capturing the exact geometry of these fleeting forms is a demanding task, as their small energy differences are highly sensitive to stereoelectronic effects and environmental perturbations. Gas-phase high-resolution spectroscopy provides precise experimental data on individual tautomers, but interpreting these measurements in structural terms requires highly accurate quantum-chemical calculations. Here, we compute benchmark-quality structures for a representative set of canonical and noncanonical nucleobase tautomers with available experimental rotational constants. The approach combines geometry optimizations─based on CCSD(T)-F12 energies with MP2 core–valence corrections─with vibrational corrections from DFT anharmonic force fields within second-order vibrational perturbation theory. The resulting near-spectroscopic accuracy enables an unbiased comparison with experiment and demonstrates the robustness of the protocol in capturing subtle structural features. Building on this, we extend the study to fluorinated and sulfur-containing pyrimidine derivatives for which no gas-phase data are available, providing reference-quality structural parameters to guide and accelerate future high-resolution experimental and theoretical investigations.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9217–9226"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the Role of Azaborondipyrromethene as an Electron Relay in Photoinduced Events Operating in Near-Infrared Absorbing Heteroaromatics Based Dual-Dye Substituted AzaBODIPYs","authors":"Anjaiah Boligorla,&nbsp;, ,&nbsp;Sai Prasanna Palacharala,&nbsp;, ,&nbsp;Sadashiv Wadepalli,&nbsp;, ,&nbsp;Akanksha Ashok Sangolkar,&nbsp;, ,&nbsp;Gundu Venkateswarlu,&nbsp;, ,&nbsp;Priyanka Mekala,&nbsp;, ,&nbsp;Ravinder Pawar,&nbsp;, ,&nbsp;Prakriti R. Bangal*,&nbsp;, ,&nbsp;Lingamallu Giribabu*,&nbsp;, and ,&nbsp;Raghu Chitta*,&nbsp;","doi":"10.1021/acs.jpca.5c04425","DOIUrl":"10.1021/acs.jpca.5c04425","url":null,"abstract":"<p >Panchromatic dyes extending the absorption up to the near-infrared region stand out as excellent candidates for light harvesting and biological applications. One of the viable ways to construct panchromatic dyes involves the strategic selection of a molecular platform that can accommodate multiple chromophores absorbing at varied wavelength ranges. Even though azadipyrromethene (azaBODIPY) offers such a molecular skeleton, reports on broadband absorbing azaBODIPYs and related photoinduced interchromophore energy/electron transfer events intending to provide desirable functions such as electron migration and charge separation (CS) are still inadequate. In this context, multiheteroaromatic tethered azaBODIPY, <b>(PTZ)</b>_<b>2</b><b>-AB-(TPA)</b>_<b>2</b>, containing phenothiazine (PTZ) and triphenylamine (TPA) integrated into azaBODIPY core has been synthesized and light-induced electron transfer events were explored. Parallely, control compounds involving azaBODIPYs with either TPA or PTZ moieties, <b>(Ph)</b>_<b>2</b><b>-AB-(TPA)</b>_<b>2</b> and <b>(PTZ)</b>_<b>2</b><b>-AB-(Ph)</b>_<b>2</b>, and pristine <b>Et-PTZ</b> and <b>TPA</b> were synthesized, and the roles of the individual constituents in the photoinduced events are investigated. Optical absorption studies have revealed that the substitution of azaBODIPY skeleton with PTZ and TPA moieties at 1,7- and 3,5-positions enhanced the extended π-conjugation and resulted in broader absorption extending beyond 1000 nm. Electrochemical studies have displayed first oxidation from either TPA or PTZ, and first reduction from the azaBODIPY moieties indicating that TPA or PTZ would behave as electron donors and azaBODIPY as the electron acceptor, and computational studies have corroborated the results. Steady-state fluorescence studies in solvents of varied polarity, involving selective excitation of PTZ at 265 nm and TPA at 300 nm resulted in quenching of the PTZ or TPA emission indicating the occurrence of photoinduced electron transfer (PET) from ¹PTZ* or ¹TPA* to azaBODIPY. Time-correlated single photon counting studies confirmed the quenching of overall lifetimes of the azaBODIPYs indicating the presence of PET within these systems. Systematic femtosecond transient absorption studies revealed the optical signatures of TPA^+• or PTZ^+• displayed at 550 and 650 nm, respectively, authenticating the occurrence of PET from excited TPA or PTZ to azaBODIPY with a very short formation time of CS states (14, 61, and 7 ps for <b>(PTZ)</b>_<b>2</b><b>-AB-(Ph)</b>_<b>2</b>, <b>(Ph)</b>_<b>2</b><b>-AB-(TPA)</b>_<b>2</b> and <b>(PTZ)</b>_<b>2</b><b>-AB-(TPA)</b>_<b>2</b>, respectively), and a long charge recombination in the nanosecond time domain, and highlighted the versatility of azaBODIPY as an electron relay in light-induced events.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9227–9242"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron Density Redistribution as a Descriptor for Excited-State Reactivity","authors":"Cristian J. Guerra*,&nbsp;","doi":"10.1021/acs.jpca.5c03467","DOIUrl":"10.1021/acs.jpca.5c03467","url":null,"abstract":"<p >This study introduces the electronic redistribution function, <i>Δρ</i>_<i>ij</i>(<b>r</b>), as a descriptor for analyzing excited-state reactivity in photochemical processes. Building upon the Quantum Theory of Atoms in Molecules (QTAIM) and state-specific density partitioning, <i>Δρ</i>_<i>ij</i>(<b>r</b>) quantifies electron density changes between two electronic states (<i>i</i> and <i>j</i>) and identifies reactive sites by integrating charge redistribution over atomic basins. This approach includes state weights (<i>c</i>_<i>i</i>², <i>c</i>_<i>j</i>²) to ensure physically meaningful interpretations of density differences. Applied to diverse systems─including the [2 + 2] cycloaddition of ethylene, Paternò-Büchi reactions of carbonyl/thiocarbonyl compounds, and photocyclizations of 1,3-butadiene─the descriptor reveals distinct reactivity patterns. For instance, <i>Δρ</i>_<i>ij</i>(<b>r</b>) delineates charge depletion (δ⁺) and accumulation (δ^–) sites, predicting interactions that drive photoproduct formation. The framework is further extended to analyze conical intersection regions, offering insights into bond-forming mechanisms for processes such as benzene isomerization and ethylene cycloaddition.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9423–9433"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145147123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exciton Basis Description of Ultrafast Triplet Separation in Pentacene-(Tetracene)2-Pentacene Intramolecular Singlet Fission Chromophore","authors":"Arifa Nazir,&nbsp;, ,&nbsp;Alok Shukla,&nbsp;, and ,&nbsp;Sumit Mazumdar*,&nbsp;","doi":"10.1021/acs.jpca.5c03774","DOIUrl":"10.1021/acs.jpca.5c03774","url":null,"abstract":"<p >Precise understanding of the electronic structures of optically dark triplet–triplet multiexcitons of π-conjugated carbon-based systems requires computations incorporating configuration interaction (CI) with up to quadruple excitations from the single-particle ground state of many-electron Hamiltonians. This continues to be a challenge in the context of intramolecular singlet fission (iSF), where the systems of interest are oligomers of large monomer molecules, and CI matrices have dimensions of several million. We have performed many-body calculations of the complete set of excited states relevant to iSF in Pentacene-(Tetracene)2-Pentacene oligomers, consisting of two terminal pentacene monomers linked by two tetracene monomers. Our computations within the Pariser–Parr–Pople Hamiltonian use an exciton basis that gives physical pictorial descriptions of all of the eigenstates. They are performed over an active space of twenty-eight monomer molecular orbitals and include configuration interaction with all relevant quadruple excitations within the active space, thereby ensuring high accuracy. We discuss the many-electron structures of the lowest optical predominantly intramonomer spin-singlets, intermonomer charge-transfer excitations, and most importantly, the complete set of low-energy covalent triplet–triplet multiexcitons. We can explain the weak binding energy of the pentacene-tetracene triplet–triplet eigenstate that is generated immediately following photoexcitation as opposed to the large binding energy of the triplet–triplet in polypentacene. Our approach allows calculations of excited state absorptions (ESAs) from the optical singlet as well as the triplet–triplet, thereby making comparisons with experimental transient absorption measurements in Pentacene-(Tetracene)2-Pentacene feasible. We explain the increase in lifetime with increasing numbers of tetracene monomers of the transient absorption associated with contiguous pentacene-tetracene triplet–triplet oligomers in this family of oligomers. We are able to give a pictorial description of the triplet separation following generation of the initial triplet–triplet, leading to a state with individual triplets occupying only the two pentacene monomers. We expect many applications of our theoretical approach to triplet separation in the iSF.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9139–9148"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliable Structures and Electronic Energies of Small Water Clusters Using Density Functional and Local Correlation Coupled Cluster Model Chemistries","authors":"Benjamin T. Petty,&nbsp;, ,&nbsp;Vance R. Fowler,&nbsp;, ,&nbsp;Audrey Ryu,&nbsp;, ,&nbsp;Caroline S. Glick,&nbsp;, ,&nbsp;Carly A. Rock,&nbsp;, ,&nbsp;Qihang Wang,&nbsp;, ,&nbsp;Gregory S. Tschumper*,&nbsp;, and ,&nbsp;George C. Shields*,&nbsp;","doi":"10.1021/acs.jpca.5c04923","DOIUrl":"10.1021/acs.jpca.5c04923","url":null,"abstract":"<p >In this paper we have assessed the ability of the domain-based local pair natural orbital (DLPNO)-CCSD(T) method to match the explicitly correlated CCSD(T) relative energies of (H₂O)_{<i>n</i>=3–7} isomers along with the impact of the level of theory utilized to optimize the water cluster geometries. The benchmark structures were optimized using a 2-body:Many-body procedure in which all of the 1- and 2-body contributions are computed using CCSD(T) while all of the higher-order many-body interactions are computed using MP2 (denoted CCSD(T):MP2). Benchmark relative energies were computed for these CCSD(T):MP2 optimized geometries with explicitly correlated CCSD(T)-F12b single point energies (SPEs) using the cc-pVQZ-F12 and cc-pV5Z-F12 basis sets augmented with diffuse functions on the O atoms. The benchmark structures and energies were used to gauge the performance of less demanding computational protocols. For example, DLPNO–CCSD(T) computations on the 31 benchmark structures with the analogous family of correlation consistent basis sets (cc-pVNZ for H and aug-cc-pVNZ for O, or simply haNZ where N = D-6) were used to estimate relative energies at the complete basis set (CBS) limit via three-point extrapolations. When compared to the CCSD(T)-F12 benchmark data, the mean absolute differences (MADs) were ≤ 0.13 kcal/mol when triple-ζ and larger basis sets were employed. Using these DLPNO–CCSD(T) results, we demonstrate that 2 less-demanding geometry optimization procedures, specifically the ωB97X-D density functional theory (DFT) method paired with the 6–31++G(d,p) basis set and the density-fitted MP2 method paired with the haTZ basis set, give structures that yield nearly identical relative energies (MADs of only 0.07 and 0.02 kcal/mol, respectively, when comparing DLPNO–CCSD(T)/ha6Z data). In addition, we show how the presence or absence of diffuse functions in the basis sets used for DLPNO–CCSD(T) SPEs impact the quality of the relative energies. The protocol that combines ωB97X-D/6–31++G(d,p) optimized structures with DLPNO–CCSD(T) SPEs using triple-ζ or higher Dunning basis sets that include augmentation with diffuse functions on the oxygen atoms provides a fast and accurate method for determining the relative electronic energies of (H₂O)_{<i>n</i>=3–7} water cluster isomers.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9291–9302"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c04923","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photodissociation Dynamics in (N2)n+ Clusters","authors":"John R. C. Blais,&nbsp;, ,&nbsp;B. Wade Stratton,&nbsp;, ,&nbsp;Nathan J. Dynak,&nbsp;, ,&nbsp;Brandon M. Rittgers,&nbsp;, ,&nbsp;D. J. Kellar,&nbsp;, and ,&nbsp;Michael A. Duncan*,&nbsp;","doi":"10.1021/acs.jpca.5c05798","DOIUrl":"10.1021/acs.jpca.5c05798","url":null,"abstract":"<p >(N₂)_<i>n</i>⁺ cluster ions are produced and cooled in a pulsed-discharge supersonic expansion and studied with UV laser photodissociation and velocity-map imaging (VMI). All cluster sizes up to <i>n</i> = 15 absorb strongly near 355 nm, and those with <i>n</i> &gt; 3 dissociate to produce both N₂⁺ and N₄⁺ photofragments. This suggests that the N₄⁺ ion is the chromophore in the larger clusters, consistent with the previous optical spectroscopy and bond energy determinations. Photofragment imaging of N₄⁺ produces an anisotropic distribution peaked along the laser polarization. Analysis of the maximum kinetic energy release produces a dissociation energy consistent with values determined in previous experiments. Dissociation of larger clusters produces N₂⁺ with significant kinetic energy values that do not change appreciably with cluster size. This suggests that the N₄⁺ core ion is not enclosed by the clustering of additional N₂ molecules. N₄⁺ fragments from larger clusters have somewhat lower kinetic energies than the N₂⁺ fragments, consistent with recombination or partial caging after dissociative recoil. However, the kinetic energy release of N₄⁺ is also considerable and it persists in the dissociation of larger clusters. This suggests that the N₄⁺ ion in these clusters resides near the surface and that the photodissociation and recombination are mediated by this surface rather than by a true caging effect.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 40","pages":"9387–9396"},"PeriodicalIF":2.8,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c05798","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}