Journal of Chemical Physics最新文献

{"title":"Evaluation of quantum offset in velocity imaging-based electron spectrometry.","authors":"Rui Zhang, Shuaiting Yan, Wenru Jie, Jiayi Chen, Qihan Liu, Chuangang Ning","doi":"10.1063/5.0332540","DOIUrl":"https://doi.org/10.1063/5.0332540","url":null,"abstract":"<p><p>Velocity-map imaging of electrons is a pivotal technique in chemical physics. A recent study reported a quantum offset as large as 0.2 cm-1 in velocity imaging-based electron spectrometry [C. Blondel and C. Drag, Phys. Rev. Lett. 134, 043001 (2025)]. In this work, we assess the existence of this offset through a combination of simulations and experiments. Our simulations reveal that the velocity imaging results reconstructed using the maximum entropy velocity Legendre reconstruction method exhibit no such offset. Furthermore, experimental measurements of the electron affinity of oxygen conducted at various imaging voltages show no discernible offset attributable to the electric field in the photodetachment region. Therefore, we conclude that there is no evidence for the claimed quantum offset in properly analyzed velocity imaging-based electron spectrometry.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838629","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":"Elliptically polarized high-order harmonic generation by controlling quantum paths with two-dimensional laser fields.","authors":"Chunyang Zhai, Yifan Liu, Xiaosong Zhu, Fengrun Wu, Jiapeng Li, Pu Wang, Jingkun Xu, Qiming Zhao, Qingbin Tang, Yingbin Li, Baichao Liu, Benhai Yu","doi":"10.1063/5.0331989","DOIUrl":"https://doi.org/10.1063/5.0331989","url":null,"abstract":"<p><p>Circularly and elliptically polarized high-order harmonics are powerful tools for probing ultrafast dynamics in chiral and magnetic materials. However, previous methods for generating elliptically polarized harmonics impose stringent requirements on the driving laser or the target medium. Here, we present a new method for generating harmonics with tunable ellipticity by driving both atoms and randomly aligned molecules with a two-dimensional two-color field. This field consists of an elliptically polarized fundamental component and a linearly polarized second-harmonic component, which together control the two-dimensional electron motion and hence the intra-cycle interference of harmonic radiation, resulting in elliptically polarized harmonics. Molecular structure effects can further modulate the harmonic polarization, enabling the generation of harmonics with consistently positive or negative helicity across a broad spectral range as well as the synthesis of attosecond pulses with high ellipticity. Our method provides a broadly applicable and flexible approach to generating elliptically polarized high-order harmonics and attosecond pulses.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838634","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":"p-H2 vs o-D2 clusters: From liquid-like to glass-like behavior.","authors":"Colin Schiltz, Vladimir A Mandelshtam","doi":"10.1063/5.0327108","DOIUrl":"https://doi.org/10.1063/5.0327108","url":null,"abstract":"<p><p>Motivated by fascinating structural properties, as well as emerging numerical challenges, para-hydrogen clusters have been explored in numerous publications in the past. Despite the enormous computational resources used by a number of groups, involving various methods, no consensus on the clusters' energetic and structural properties has been established. Most studies reported strong size dependencies, e.g., \"magic number\" clusters, while strongly disagreeing with each other quantitatively. Only a few studies claimed the lack of size-sensitivity. That is, hardly more than a couple of reports could be considered numerically converged and/or physically meaningful. Unlike most of the previous studies, we focus on a small size range of Lennard-Jones LJ34-39 clusters, for which, using Diffusion Monte Carlo (DMC), we attempt to capture the true behavior of the systems accurately. Not only do we demonstrate that the (p-H2)N clusters for the chosen sizes have the ground state wavefunctions strongly delocalized over thousands of structurally identical isomers, but we also vary the quantum delocalization parameter Λ in the effective range between the hydrogen (ΛH2∼0.28) and deuterium (ΛD2∼0.20) regimes. We show that for the o-D2 clusters, the ground state wavefunctions are strongly localized, yet they are still disordered. In this regime, the system dynamics associated with the DMC method becomes non-ergodic, e.g., the random walkers get trapped in the potential energy minima where they have been initialized. (It is ergodic for hydrogen clusters.) Consequently, we suggest that the structural change induced by decreasing the quantum parameter Λ from p-H2 to o-D2 has the character of a \"liquid-glass\" transition.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838710","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":"Elongational flow response of compressible polymer melts.","authors":"Rosita Sivaraj, John M Bracewell, Thomas C O'Connor, Dvora Perahia, Gary S Grest","doi":"10.1063/5.0325571","DOIUrl":"https://doi.org/10.1063/5.0325571","url":null,"abstract":"<p><p>The molecular-level flow response of macromolecules underlies their rheological behavior and affects their processing. The correlation between molecular characteristics, such as polymer rigidity and compressibility, and their macroscopic rheological response remains an open question. With coarse-grained molecular dynamics simulations, the current study explores the effects of polymer rigidity and compressibility on their flow response for both linear and ring polymers. We find that, as for incompressible polymers, the chains extend along the flow direction for both architectures. In contrast to incompressible polymers, the systems undergo a flow-induced transition at high flow rates, in which the viscosity and density increase dramatically, independent of chain length. In ring polymers, at high flow rates, topological links or knots give rise to a large increase in extensional viscosity before the onset of the flow-induced transition.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838558","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":"Nanoparticle-polymer coupling in magnetic gels studied by means of computer simulations and experiments.","authors":"Rebecca Stephan, Surojit Ranoo, Patrick Kreissl, Chinmay Pabshettiwar, Jessica Kubis, Christian Holm, Annette M Schmidt, Regine von Klitzing, Rudolf Weeber","doi":"10.1063/5.0323088","DOIUrl":"https://doi.org/10.1063/5.0323088","url":null,"abstract":"<p><p>Magnetic gels are soft hydrogels with incorporated magnetic nanoparticles, combining viscoelastic properties with responsiveness to magnetic fields. In many experimentally relevant systems, the nanoparticles are not covalently attached to the polymer network but are instead physically trapped within its meshes. Despite this weak mechanical coupling, experiments reveal signatures of hindered rotational dynamics. Here, we investigate the microscopic origin of this behavior by combining experiments on polyacrylamide hydrogels loaded with cobalt ferrite nanoparticles with simulations that explicitly account for polymers, nanoparticles, and hydrodynamic interactions. We probe the nanoparticle-polymer coupling by exploring the systems' magnetic AC susceptibility-a quantity that is accessible both by experiment and in simulations, and that is sensitive to rotational dynamics. Experimentally, we observe a reduced low-frequency susceptibility, indicating partial orientational blocking of the nanoparticles, even in the absence of covalent bonding. Simulations show that this behavior cannot be explained by hydrodynamic coupling or isotropic van der Waals-like interactions alone. Instead, our results demonstrate that a degree of preferential attachment of polymers to spots on the nanoparticle surface-arising from chemical or topographical heterogeneity-is essential to reproduce the experimentally observed response.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838559","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":"Nonadiabatic rare events from transition-path sampling of MASH trajectories.","authors":"Danial Ghamari, Jeremy O Richardson","doi":"10.1063/5.0321299","DOIUrl":"https://doi.org/10.1063/5.0321299","url":null,"abstract":"<p><p>Rare nonadiabatic reactions are a key component of many important molecular processes, but are challenging to capture with direct dynamical simulations. In this paper, we combine our recently developed mapping approach to surface hopping (MASH) with transition-path sampling to create a framework to efficiently simulate these rare events. This is possible because MASH trajectories are Markovian, time-reversible, and obey Liouville's theorem. The combined approach generates nonadiabatic reactive pathways without biasing the underlying dynamics. The resulting ensemble allows for a detailed analysis of reaction mechanisms and the unraveling of statistical and dynamical properties, including rate constants. We apply the method to study a spin-boson model in thermal equilibrium over a wide range of diabatic coupling strengths. Our results demonstrate how this approach provides a practical and systematic tool for investigating rare nonadiabatic processes, potentially beyond the reach of brute-force simulations.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838614","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":"Active subspace learning for coarse-grained molecular dynamics.","authors":"Anna Wojnar, Stephen Pankavich, Alexander J Pak","doi":"10.1063/5.0316662","DOIUrl":"https://doi.org/10.1063/5.0316662","url":null,"abstract":"<p><p>We introduce Active Subspace Coarse-Graining (ASCG), an interpretable framework for systematic bottom-up coarse-graining trained from atomistic molecular dynamics simulations that simultaneously defines the coarse-grained mapping, effective interactions, and the equations of motion within one unified mathematical framework. We employ active subspace learning to identify linear projections of atomistic degrees of freedom that maximally describe gradients of the potential energy, yielding a reduced set of coarse-grained variables that capture the dominant collective motions across the potential of mean force. Effective coarse-grained forces and noise terms are obtained directly from the same projection, eliminating the need for separate parameterization schemes. We demonstrate ASCG on three biomolecular systems (dialanine, Trp-cage, and chignolin), showing that the method captures many-body intramolecular conformational effects while eliminating all solvent degrees of freedom and reducing solute dimensionality by more than 90%. The resulting free energy surfaces are recapitulated with Jensen-Shannon divergences as low as 0.034. ASCG trajectories are integrated with time steps up to 100 fs, around four to ten times larger than those possible with conventional coarse-graining methods, while ASCG models remain accurate with as little as 100 ns of training data. In its current formulation, ASCG operates on global intramolecular representations and is, therefore, best suited to single-molecule systems, while future extensions to intermolecular interactions will require locality-aware representations. Nonetheless, these results establish ASCG as a robust, data-efficient approach for learning coarse-grained representations of complex intramolecular forces while representing a departure from traditional particle-based models.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838096","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":"Wertheim association theory for ion pairing in electrolytes: The effect of neutral clusters.","authors":"Patrick B Warren, Andrew J Masters","doi":"10.1063/5.0316777","DOIUrl":"https://doi.org/10.1063/5.0316777","url":null,"abstract":"<p><p>We address the problem of the vapor-liquid phase transition in the restricted primitive model (RPM) using Wertheim's statistical associating fluid theory to capture the effects of ion pairing, which dominate the low-temperature vapor phase. For this, we employ a reference system in which ion-pairing is suppressed by a judicious modification of the interaction between unlike charges, from 1/r to erf(κr)/r, where the state-point-dependent parameter κ is chosen so that the Helmholtz free energy A is at a null point (∂A/∂κ = 0). Unlike the original RPM, this reference fluid admits real solutions to the hypernetted-chain closure of the Ornstein-Zernike equations over a wide range of densities and temperatures. In the present study, we go beyond previous work [M. Li, Ph.D. thesis, University of Manchester, 2011] to allow ion pairs to assemble into neutral clusters. We find that this has the potential to improve significantly the agreement with the Monte Carlo results for the RPM vapor phase boundary. We can also match recent results on anomalous underscreening in the RPM [A. Härtel et al., Phys. Rev. Lett. 130, 108202 (2023)], assuming that only the free ions contribute to the screening length.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838134","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":"Characterizing nanostructured films using phase sensitive vibrational sum frequency spectroscopy.","authors":"Furong Yan, Carsten Placke-Yan, Aleyna Yasar, Zhipeng Huang, Gerd Bacher, Stephan Schulz, Yujin Tong, R Kramer Campen","doi":"10.1063/5.0321067","DOIUrl":"https://doi.org/10.1063/5.0321067","url":null,"abstract":"<p><p>Nanoparticle films are ubiquitous thermal and electrocatalysts, yet their operando characterization remains challenging. Vibrational sum-frequency generation (vSFG) spectroscopy offers unique advantages due to its high sensitivity and surface specificity, but its application to systems with such intermediate length scale disorder, particularly with phase-resolved detection, has been challenging. In this study, we describe an approach to phase-resolved vSFG spectroscopy of nanoparticle films using z-cut α-quartz as a local reference. We show, by analysis of an octadecyltrichlorosilane film on quartz under the ppp polarization condition, that quantitative detection of absolute phase is possible and subsequently apply this protocol to a film of Mn-doped Co3O4 nanoparticles. Two OH species are resolved (∼3585 and ∼3770cm-1), both oriented H-up relative to the surface. This approach delivers a practical, internally referenced, phase-resolved vSFG methodology for nanoparticle ensembles on dielectric supports and, therefore, offers operando access to catalytic interfaces beyond metallic or plasmonically enhanced systems.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838356","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":"Consistent inclusion of triple substitutions within a coupled cluster based static quantum embedding theory.","authors":"Avijit Shee, Fabian M Faulstich, K Birgitta Whaley, Lin Lin, Martin Head-Gordon","doi":"10.1063/5.0327679","DOIUrl":"https://doi.org/10.1063/5.0327679","url":null,"abstract":"<p><p>We have previously proposed the MPCC static embedding framework for quantum chemistry that self-consistently couples a high-level coupled cluster (CC) treatment of the fragment (active region) with a lower level, Møller-Plesset perturbation treatment of the environment. Our initial implementation was limited to single and double (SD) substitutions, with CCSD for the fragment and first-order perturbative SD amplitudes for the environment. Here, we extend the MPCC embedding treatment to triple substitutions, which is essential for achieving chemical accuracy in energy differences. To this end, we employ a CCSDT solver for the fragment subsystem. For the environment subsystem, we construct a perturbative estimate of the triples amplitudes, explicitly accounting for feedback from all fragment amplitudes. The resulting approach is denoted MPCCSDT(pt). We further introduce a more complete formulation in which feedback from the environment amplitudes to the fragment amplitudes is also included. This scheme involves an iterative treatment of the environment triples amplitudes and is denoted MPCCSDT(it). In addition, we assess the accuracy of the previously proposed low-level method by introducing a modified low-level approach that incorporates a lowest-order treatment of selected long-range effects, including spin fluctuations and charge polarization. All resulting approaches may be viewed as post-CCSD(T) methods. We therefore consider test cases for which CCSD(T) exhibits substantial deviations from CCSDT. These include (i) single- and triple-bond stretching in F2 and N2, (ii) bond dissociation energies of selected molecules from the W4-11 dataset, and (iii) total atomization energies of transition metal hydrides. Our results demonstrate that inclusion of triples amplitudes at the fragment level alone is insufficient; a perturbative treatment of the environment triples amplitudes is required. For many energy-difference applications, feedback from the environment triples amplitudes to the fragment amplitudes is not essential, but it does play a role in the very challenging CoH and FeH molecules. A very interesting finding from our study is that in some challenging cases, we need an improved (second-order) perturbative method for the SD amplitudes, going beyond the first-order one used in our earlier work. Considering both cost and accuracy, the MP2CCSDT(pt) model is the most promising for future applications among the candidates considered here.</p>","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":"164 17","pages":""},"PeriodicalIF":3.1,"publicationDate":"2026-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838402","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}