Journal of Chemical Physics最新文献_第2页

Nitrosation mechanisms, kinetics, and dynamics of the guanine and 9-methylguanine radical cations by nitric oxide-Radical-radical combination at different electron configurations. 一氧化氮-自由基-自由基组合在不同电子构型下对鸟嘌呤和 9-甲基鸟嘌呤自由基阳离子的亚硝化机制、动力学和动力学。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0230367

Jonathan Benny, Toru Saito, Jianbo Liu

{"title":"Nitrosation mechanisms, kinetics, and dynamics of the guanine and 9-methylguanine radical cations by nitric oxide-Radical-radical combination at different electron configurations.","authors":"Jonathan Benny, Toru Saito, Jianbo Liu","doi":"10.1063/5.0230367","DOIUrl":"https://doi.org/10.1063/5.0230367","url":null,"abstract":"As a precursor to various reactive nitrogen species formed in biological systems, nitric oxide (•NO) participates in numerous processes, including enhancing DNA radiosensitivity in ionizing radiation-based radiotherapy. Forming guanine radical cations is another common DNA lesion resulting from ionization and oxidation damage. As such, the interaction of •NO with guanine radical cations (G•+) may contribute to the radiosensitization of •NO. An intriguing aspect of this process is the participation of multiple spin configurations in the reaction, including open-shell singlet 1,OS[G•+(↑)⋯(↓)•NO], closed-shell singlet 1,CS[G(↑↓)⋯NO+], and triplet 3[G•+(↑)⋯(↑)•NO]. In this study, the reactions of •NO with both unsubstituted guanine radical cations (in the 9HG•+ conformation) and 9-methylguanine radical cations (9MG•+, a guanosine-mimicking model compound) were investigated in the absence and presence of monohydration of radical cations. Kinetic-energy dependent reaction product ions and cross sections were measured using an electrospray ionization guided-ion beam tandem mass spectrometer. The reaction mechanisms, kinetics, and dynamics were comprehended by interpreting the reaction potential energy surface using spin-projected density functional theory, coupled cluster theory, and multiconfiguration complete active space second-order perturbation theory, followed by RRKM kinetics modeling. The combined experimental and computational findings revealed closed-shell singlet 1,CS[7-NO-9MG]+ as the major, exothermic product and triplet 3[8-NO-9MG]+ as the minor, endothermic product. Singlet biradical products were not detected due to high reaction endothermicities, activation barriers, and inherent instability.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347513","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}

引用次数: 0

Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation. 通过微焦 SR-SAXS 重建和分子模拟揭示 γ 辐照预氧化 PAN 纤维的异质微观结构。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0229949

Tianyu Li, Ruiqi Shao, Haiting Shi, Shengkai Liu, Feng Tian, Jianrong Zeng, Zhiwei Xu, Fenggang Bian

{"title":"Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation.","authors":"Tianyu Li, Ruiqi Shao, Haiting Shi, Shengkai Liu, Feng Tian, Jianrong Zeng, Zhiwei Xu, Fenggang Bian","doi":"10.1063/5.0229949","DOIUrl":"https://doi.org/10.1063/5.0229949","url":null,"abstract":"The microstructure plays a crucial role in the manufacturing and application of polyacrylonitrile fibers, which serve as precursors for carbon fibers. Synchrotron radiation small angle x-ray scattering (SR-SAXS) is a non-destructive and precise technique for analyzing fiber structures. This study employed one-dimensional SR-SAXS mapping to extract key structural parameters such as periodicity, lamellae thickness, and the extent of amorphous regions, as well as the directional orientation in γ-irradiated, pre-oxidized polyacrylonitrile fibers. The analysis revealed a three-layered structure comprising a surface skin, a transitional layer, and a central core. Notably, the lamellar thickness exhibits a \"U\"-shaped distribution, while the long-period structures, amorphous regions, and orientational properties demonstrate a \"wave-like\" pattern. Within this structure, the skin exhibits a higher level of orientation, with the orientation decreasing progressively from the skin toward the core layer. The structure of the layered crystal was further corroborated by the morphological analysis. In addition, molecular simulations were performed to propose the mechanisms underlying the formation of this layered structure. This comprehensive investigation using SR-SAXS and one-dimensional mapping provides detailed insights into the microstructural and morphological characteristics of polyacrylonitrile fibers, which can inform future advancements in material processing and refinement techniques for the production of advanced fibers.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347502","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}

引用次数: 0

Interfacial local field and surface response coefficients. 界面局部场和表面响应系数

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0231281

Yuxuan Wei, Y R Shen

引用次数: 0

Closure to the PRISM equation derived from nonlinear response theory. 根据非线性响应理论得出的 PRISM 方程的封闭性。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0226882

James P Donley

{"title":"Closure to the PRISM equation derived from nonlinear response theory.","authors":"James P Donley","doi":"10.1063/5.0226882","DOIUrl":"https://doi.org/10.1063/5.0226882","url":null,"abstract":"Nonlinear response theory is employed to derive a closure to the polymer reference interaction site model equation. The closure applies to a liquid of neutral polymers at melt densities. It can be considered a molecular generalization of the mean spherical approximation (MSA) closure of Lebowitz and Percus to the atomic Ornstein-Zernike (OZ) equation and is similar in some aspects to the reference \"molecular\" MSA (R-MMSA) closure of Schweizer and Yethiraj to PRISM. For a model binary blend of freely-jointed chains, the new closure predicts an unmixing critical temperature, Tc, via the susceptibility route that scales linearly with molecular weight, N, in agreement with Flory theory. Predictions for Tc of the new closure differ greatest from those of the R-MMSA at intermediate N, the latter being about 40% higher than the former there, but at large N, both theories give about the same values. For an isotopic blend of polyethylene, the new and R-MMSA closures predict a Tc about 25% higher than the experimental value, which is only moderately less accurate than the prediction of atomic OZ-MSA theory for Tc of methane. In this way, the derivation and its consequences help to identify the ingredients in a theory needed to properly model the equilibrium properties of a polymeric liquid at both short and long lengthscales.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347491","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}

引用次数: 0

Divergences in classical and quantum linear response and equation of motion formulations. 经典与量子线性响应和运动方程公式的分歧。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0225409

Erik Rosendahl Kjellgren, Peter Reinholdt, Karl Michael Ziems, Stephan P A Sauer, Sonia Coriani, Jacob Kongsted

引用次数: 0

mpsqd: A matrix product state based Python package to simulate closed and open system quantum dynamics. mpsqd：基于矩阵乘积状态的 Python 软件包，用于模拟封闭和开放系统量子动力学。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0226214

Weizhong Guan, Peng Bao, Jiawei Peng, Zhenggang Lan, Qiang Shi

引用次数: 0

Constructing potential energy surface for carbon-chain containing systems using the radial angular network with gradual expansion method. 利用径向角网络逐步扩展法构建含碳链系统的势能面

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0229945

C T Bop, F Lique

{"title":"Constructing potential energy surface for carbon-chain containing systems using the radial angular network with gradual expansion method.","authors":"C T Bop, F Lique","doi":"10.1063/5.0229945","DOIUrl":"https://doi.org/10.1063/5.0229945","url":null,"abstract":"Investigating molecular excitation induced by collisions requires the prior determination of accurate analytical potential energy surfaces for the colliding partners. For carbon-chain molecules, such as cyanopolyynes, this has been a longstanding challenge, resulting in the absence of rate coefficients for HC5N, HC7N, HC9N, and others, induced by collisions with He. To overcome this bottleneck, we introduce a new approach: the Radial Angular Network with Gradual Expansion (RANGE). This method jointly connects the construction of ab initio interaction potentials with the determination of their analytical forms. We use the HC3N-He molecular complex as a reference to assess the reliability of our method, given that its analytical potential has been derived using various methods. Additionally, we apply the RANGE approach to construct the analytical representation of the interaction potential for HC5N-He and HC7N-He. The analysis of the analytical potentials reveals three systematic trends: (i) the anisotropy increases with the length of the carbon chain, (ii) the number of local minima correlates with the number of carbon atoms, and (iii) the shallowest local minimum is consistently located at ∼30 cm-1 below the dissociation limit of the complex. Using the time-independent quantum mechanical close-coupling formalism, we briefly estimate the propensity rules governing the excitation of HC3N, HC5N, and HC7N induced by collisions with He. Consequently, the three collisional systems exhibit the same propensity rule, favoring Δj = 2 transitions.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347493","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}

引用次数: 0

Molecular modeling and simulation of organic electrolyte solutions for lithium ion batteries. 锂离子电池有机电解质溶液的分子建模与模拟。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0228158

Pascal Zittlau, Sarah Mross, Dominik Gond, Maximilian Kohns

{"title":"Molecular modeling and simulation of organic electrolyte solutions for lithium ion batteries.","authors":"Pascal Zittlau, Sarah Mross, Dominik Gond, Maximilian Kohns","doi":"10.1063/5.0228158","DOIUrl":"https://doi.org/10.1063/5.0228158","url":null,"abstract":"Multi-criteria optimization is used for developing molecular models for ethylene carbonate (EC) and propylene carbonate (PC), organic solvents commonly used in Li-ion batteries. The molecular geometry and partial charges of the solvents are obtained from quantum mechanical calculations. Using a novel optimization strategy that combines systematic variations of the Lennard-Jones parameters with a reduced units approach, the models are fitted to experimental data on the liquid density, vapor pressure, relative permittivity, and self-diffusion coefficient. Since no experimental data for the self-diffusion coefficient of pure EC were available in the literature, they are measured in this work using a gradient-based nuclear magnetic resonance technique. For all pure component properties, excellent agreement between experiment and simulation is obtained. Moreover, the predictive capabilities of the new solvent models are assessed by comparison to experimental data for the liquid density and relative permittivity of mixtures of EC and PC. In addition, molecular models for the anions PF6-, BF4-, and ClO4- in solutions of their lithium electrolytes in PC are developed using experimental data on the solution densities. Finally, the self-diffusion coefficients of LiPF6 in PC and in aqueous solution are predicted and compared, showing that diffusion is much slower in the organic solution due to the formation of larger solvent shells around the ions. Furthermore, an analysis of the radial distribution functions in these solutions suggests that the ions have much less impact on the structure of the solvent PC than on water.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347511","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}

引用次数: 0

Blueshift or redshift? Effect of hydrogen bonding interactions on the C≡N stretching frequency of 5-cyanoindole. 蓝移还是红移？氢键相互作用对 5-氰基吲哚的 C≡N 伸展频率的影响

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0228319

Yuyao Yang, Ruoqi Zhao, Wenkai Zhang, Jiali Gao, Feng Gai

{"title":"Blueshift or redshift? Effect of hydrogen bonding interactions on the C≡N stretching frequency of 5-cyanoindole.","authors":"Yuyao Yang, Ruoqi Zhao, Wenkai Zhang, Jiali Gao, Feng Gai","doi":"10.1063/5.0228319","DOIUrl":"https://doi.org/10.1063/5.0228319","url":null,"abstract":"The nitrile (C≡N) stretching vibration is widely used as a site-specific environmental probe of proteins and, as such, many computational studies have been used to investigate the factors that affect its frequency (νCN). These studies, most of which were carried out in the ground electronic state of the molecule of interest, revealed that the formation of a normal or linear hydrogen bond (H-bond) with the nitrile group results in a blueshift in its νCN. Recently, however, several experimental studies showed that for certain aromatic nitriles, solvent relaxations in their excited electronic state(s) induce a redshift (blueshift) in νCN in protic (aprotic) solvents, suggesting that the effect of hydrogen-bonding (H-bonding) interactions on νCN may depend on the electronic state of the molecule. To test this possibility, herein we combine molecular dynamics simulations and quantum mechanical calculations to assess the effect of H-bonding interactions on the νCN of 5-cyanoindole (5-CNI) in its different electronic states. We find that its C≡N group can form either one H-bond (single-H-bond) or two H-bonds (d-H-bonds) with the solvent molecules and that in the ground electronic state, a single-H-bond can lead νCN to shift either to a higher or lower frequency, depending on its angle, which is consistent with previous studies, whereas the d-H-bonds cause νCN to redshift. However, in its lowest-lying excited electronic state (i.e., S1), which has the characteristics of a charge-transfer state, all H-bonds induce a redshift in νCN, with the d-H-bonds being most effective in this regard.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347489","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}

引用次数: 0

Endohedral metallofullerenes as nanoreactors: Regulating the ring-opening reaction of m-xylene at a molecular level under pressure. 作为纳米反应器的内层金属富勒烯：在分子水平上调节间二甲苯在压力下的开环反应。

IF 3.1 2区化学

Journal of Chemical Physics Pub Date : 2024-09-28 DOI: 10.1063/5.0223053

Ying Zhang, Shuang Liu, Si Yin, Xiu Yin, Lei Yue, Ran Liu, Bo Liu, Jiajun Dong, Xing Lu, Mingguang Yao, Wangqiang Shen, Bingbing Liu

{"title":"Endohedral metallofullerenes as nanoreactors: Regulating the ring-opening reaction of m-xylene at a molecular level under pressure.","authors":"Ying Zhang, Shuang Liu, Si Yin, Xiu Yin, Lei Yue, Ran Liu, Bo Liu, Jiajun Dong, Xing Lu, Mingguang Yao, Wangqiang Shen, Bingbing Liu","doi":"10.1063/5.0223053","DOIUrl":"https://doi.org/10.1063/5.0223053","url":null,"abstract":"The ring-opening reaction of aromatic molecules is a significant and critical process for the construction of carbon-based and related functional materials with desired structures and properties. However, direct observation and control of such a process at a molecular level remains a challenge. Here, we employed the octahedral voids in endohedral metallofullerene (EMF) crystals as nanoreactors to accommodate aromatic m-xylene molecules and regulate the ring-opening reaction of guest m-xylene by applying a high pressure. We found that the ring-opening reaction of m-xylenes strongly depends on the degree of charge transfer between m-xylene and EMF, which can be tuned by varying the electronegativity of the carbon cages with different endohedral metals. A positive relationship between the electronegativity of fullerenes and the reactivity of m-xylene was revealed. This work demonstrates the potential of tuning the ring-opening reaction of aromatic molecules by charge transfer and manipulates the reaction at a molecule level, providing new insights into the synthesis of carbon materials and fullerene derivatives.","PeriodicalId":15313,"journal":{"name":"Journal of Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142347500","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}

引用次数: 0