Damiano Aliverti-Piuri, Kaustav Chatterjee, Lexin Ding, Ke Liao, Julia Liebert, Christian Schilling
It is the ultimate goal of this work to foster synergy between quantum chemistry and the flourishing field of quantum information theory. For this, we first translate quantum information concepts such as entanglement and correlation into the context of quantum chemical systems. In particular, we establish two conceptually distinct perspectives on correlation leading to a notion of orbital and particle correlation. We then demonstrate that particle correlation equals orbital correlation minimized with respect to all orbital reference bases. Accordingly, particle correlation resembles the minimal, thus intrinsic, complexity of many-electron wavefunctions while orbital correlation quantifies their complexity relative to a basis. We illustrate these novel concepts of intrinsic and extrinsic correlation complexity with analytic and numerical examples, which also demonstrates the crucial link between the two correlation pictures. Our results provide theoretical justification for the long-favored natural orbitals for simplifying electronic structures, and open new pathways for developing more efficient approaches towards the electron correlation problem.
{"title":"What can Quantum Information Theory Offer to Quantum Chemistry?","authors":"Damiano Aliverti-Piuri, Kaustav Chatterjee, Lexin Ding, Ke Liao, Julia Liebert, Christian Schilling","doi":"10.1039/d4fd00059e","DOIUrl":"https://doi.org/10.1039/d4fd00059e","url":null,"abstract":"It is the ultimate goal of this work to foster synergy between quantum chemistry and the flourishing field of quantum information theory. For this, we first translate quantum information concepts such as entanglement and correlation into the context of quantum chemical systems. In particular, we establish two conceptually distinct perspectives on correlation leading to a notion of orbital and particle correlation. We then demonstrate that particle correlation equals orbital correlation minimized with respect to all orbital reference bases. Accordingly, particle correlation resembles the minimal, thus intrinsic, complexity of many-electron wavefunctions while orbital correlation quantifies their complexity relative to a basis. We illustrate these novel concepts of intrinsic and extrinsic correlation complexity with analytic and numerical examples, which also demonstrates the crucial link between the two correlation pictures. Our results provide theoretical justification for the long-favored natural orbitals for simplifying electronic structures, and open new pathways for developing more efficient approaches towards the electron correlation problem.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Kats, Evelin Martine Corvid Christlmaier, Thomas Schraivogel, Ali Alavi
We present a combination of the bi-orthogonal orbital optimisation framework with the recently introduced xTC version of transcorrelation. This allows us to implement non-iterative perturbation based methods on top of the transcorrelated Hamiltonian. Besides, the orbital optimisation influences results of other truncated methods, such as the distinguishable cluster with singles and doubles. The accuracy of these methods in comparison to standard xTC methods is demonstrated, and the advantages and disadvantages of the orbital optimisation are discussed.
{"title":"Orbital optimisation in xTC transcorrelated methods","authors":"Daniel Kats, Evelin Martine Corvid Christlmaier, Thomas Schraivogel, Ali Alavi","doi":"10.1039/d4fd00036f","DOIUrl":"https://doi.org/10.1039/d4fd00036f","url":null,"abstract":"We present a combination of the bi-orthogonal orbital optimisation framework with the recently introduced xTC version of transcorrelation. This allows us to implement non-iterative perturbation based methods on top of the transcorrelated Hamiltonian. Besides, the orbital optimisation influences results of other truncated methods, such as the distinguishable cluster with singles and doubles. The accuracy of these methods in comparison to standard xTC methods is demonstrated, and the advantages and disadvantages of the orbital optimisation are discussed.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate ab initio calculations of real solids are of fundamental importance in fields such as chemistry, phases and materials science. Recently, variational Monte Carlo (VMC) based on neural network wavefunction has been developed as a promising option to solve the existing challenges in ab initio calculations. In this study, we discuss the calculation of interatomic force and stress tensor of real solids with neural network--based VMC method. A new scheme of computing force is proposed based on the space warp coordination transformation method, which achieves better accuracy, efficiency and robustness than existing methods. In addition, we also designed new periodic features of neural network to further improve the robustness of force calculations for different lattices. This work paves the way for further extending the application of machine learning quantum Monte Carlo in materials modelling.
在化学、相学和材料科学等领域，对实际固体进行精确的 ab initio 计算至关重要。最近，基于神经网络波函数的变分蒙特卡罗（VMC）作为一种有前途的选择被开发出来，以解决现有的非初始计算难题。在本研究中，我们讨论了用基于神经网络的 VMC 方法计算实际固体的原子间力和应力张量。我们提出了一种基于空间翘曲协调变换方法的力计算新方案，与现有方法相比，该方案具有更高的精度、效率和鲁棒性。此外，我们还设计了新的神经网络周期特征，进一步提高了不同晶格下力计算的鲁棒性。这项工作为进一步扩展机器学习量子蒙特卡洛在材料建模中的应用铺平了道路。
{"title":"Force and stress calculation with neural network wavefunction for solids","authors":"Yubing Qian, Xiang Li, Ji Chen","doi":"10.1039/d4fd00071d","DOIUrl":"https://doi.org/10.1039/d4fd00071d","url":null,"abstract":"Accurate <em>ab initio</em> calculations of real solids are of fundamental importance in fields such as chemistry, phases and materials science. Recently, variational Monte Carlo (VMC) based on neural network wavefunction has been developed as a promising option to solve the existing challenges in <em>ab initio</em> calculations. In this study, we discuss the calculation of interatomic force and stress tensor of real solids with neural network--based VMC method. A new scheme of computing force is proposed based on the space warp coordination transformation method, which achieves better accuracy, efficiency and robustness than existing methods. In addition, we also designed new periodic features of neural network to further improve the robustness of force calculations for different lattices. This work paves the way for further extending the application of machine learning quantum Monte Carlo in materials modelling.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Strong correlation has been said to have many faces, and appears to have many synonyms of questionable suitability. In this work we aim not to define the term once and for all, but to highlight one possibility that is both rigorously defined and physically transparent, and remains so in reference to molecules and quantum lattice models. We survey both molecular examples -- hydrogen systems (H$_text{n}$, n=2, 4, 6), Be$_2$, H-He-H, and benzene -- and the half-filled Hubbard model over a range of correlation regimes. Various quantities are examined including the extent of spin symmetry breaking in correlated single-reference wavefunctions, energetic ratios inspired by the Hubbard model and the Virial theorem, and metrics derived from the one- and two-electron reduced density matrices. The trace and the square norm of the cumulant of the two-electron reduced density matrix capture what may well be defined as strong correlation, and are consistent with more familiar chemical concepts such as Baird's rule of (anti)aromaticity. Accordingly, strong correlation is understood as a statistical dependence between two electrons, and is distinct from the concepts of ``correlation energy" and more general than entanglement quantities that require a partitioning of a quantum system (presupposing some distinguishability of fermions).
{"title":"On the notion of strong correlation in electronic structure theory","authors":"Brad Ganoe, James Shee","doi":"10.1039/d4fd00066h","DOIUrl":"https://doi.org/10.1039/d4fd00066h","url":null,"abstract":"Strong correlation has been said to have many faces, and appears to have many synonyms of questionable suitability. In this work we aim not to define the term once and for all, but to highlight one possibility that is both rigorously defined and physically transparent, and remains so in reference to molecules and quantum lattice models. We survey both molecular examples -- hydrogen systems (H$_text{n}$, n=2, 4, 6), Be$_2$, H-He-H, and benzene -- and the half-filled Hubbard model over a range of correlation regimes. Various quantities are examined including the extent of spin symmetry breaking in correlated single-reference wavefunctions, energetic ratios inspired by the Hubbard model and the Virial theorem, and metrics derived from the one- and two-electron reduced density matrices. The trace and the square norm of the cumulant of the two-electron reduced density matrix capture what may well be defined as strong correlation, and are consistent with more familiar chemical concepts such as Baird's rule of (anti)aromaticity. Accordingly, strong correlation is understood as a statistical dependence between two electrons, and is distinct from the concepts of ``correlation energy\" and more general than entanglement quantities that require a partitioning of a quantum system (presupposing some distinguishability of fermions).","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jake Seymour, Ekaterina Gousseva, Frances Towers Tompkins, Lewis Parker, Najaat Alblewi, Coby James Clarke, Shusaku Hayama, Robert Palgrave, Roger Bennett, Richard Paul Matthews, Kevin R. J. Lovelock
Using a combination of liquid-phase experimental X-ray spectroscopy experiments and small-scale calculations we have gained new insights into the speciation of halozincate anions in ionic liquids (ILs). Both core and valence X-ray photoelectron spectroscopy (XPS) were performed directly on the liquid-phase ILs, supplemented by Zn 1s X-ray absorption near edge structure (XANES) spectroscopy. Density functional theory (DFT) calculations were carried out on both 1- and 2- halozincate anions, in both a generalised solvation model SMD (Solvation Model based on Density) and the gas phase, to give XP spectra and total energy differences; time-dependent DFT was used to calculate XA spectra. Speciation judgements were made using a combination of the shape and width of experimental spectra, and visual matches to calculated spectra. For 2- halozincate anions, excellent matches were found between experimental and calculated XP spectra, clearly showing that only 2- halozincate anions were present at all zinc halide mole fraction, x, studied. At specific x (0.33, 0.50, 0.60) only one halozincate anion was present; equilibria of different halozincate anions at those x were not observed. All findings show that chlorozincate anion and bromozincate anion speciation matched at the same x. Based on the results, predictions are made of the halozincate anion speciation for all x up to 0.67. Caution is advised when using differences in calculated total energies obtained from DFT to judge halozincate anion speciation, even when the SMD was employed, as predictions based on total energy differences did not always match the findings from experimental and calculated spectra. Our findings clearly establish that the combination of high-quality experimental data from multiple spectroscopies and a wide range of calculated structures are essential to have high confidence in halozincate anion speciation identification.
利用液相 X 射线光谱实验和小规模计算相结合的方法，我们对离子液体（ILs）中卤代锌酸盐阴离子的标示有了新的认识。我们直接在液相离子液体中进行了核心和价态 X 射线光电子能谱（XPS）实验，并辅以 Zn 1s X 射线吸收近边缘结构（XANES）能谱。在广义溶解模型 SMD（基于密度的溶解模型）和气相中，对 1-和 2-卤代锌酸盐阴离子进行了密度泛函理论（DFT）计算，以得出 XP 光谱和总能差；并使用随时间变化的 DFT 计算 XA 光谱。结合实验光谱的形状和宽度以及与计算光谱的目视匹配来进行物种判断。对于卤代锌酸盐阴离子，实验和计算的 XP 光谱非常吻合，清楚地表明在研究的所有卤化锌摩尔分数 x 下，只有卤代锌酸盐阴离子存在。在特定的 x（0.33、0.50、0.60）条件下，只存在一种卤代锌酸盐阴离子；在这些 x 条件下，没有观察到不同卤代锌酸盐阴离子的平衡。所有研究结果都表明，在相同的 x 条件下，氯锌酸盐阴离子和溴锌酸盐阴离子的种类是一致的。在使用 DFT 计算得出的总能量差异来判断卤代锌酸盐阴离子的种类时，即使使用了 SMD，也要谨慎，因为基于总能量差异的预测并不总是与实验和计算光谱的结果相吻合。我们的研究结果清楚地表明，要想在卤锌酸盐阴离子种类鉴定中获得较高的置信度，就必须将来自多种光谱的高质量实验数据和广泛的计算结构结合起来。
{"title":"Unravelling the complex speciation of halozincate ionic liquids using X-ray spectroscopies and calculations","authors":"Jake Seymour, Ekaterina Gousseva, Frances Towers Tompkins, Lewis Parker, Najaat Alblewi, Coby James Clarke, Shusaku Hayama, Robert Palgrave, Roger Bennett, Richard Paul Matthews, Kevin R. J. Lovelock","doi":"10.1039/d4fd00029c","DOIUrl":"https://doi.org/10.1039/d4fd00029c","url":null,"abstract":"Using a combination of liquid-phase experimental X-ray spectroscopy experiments and small-scale calculations we have gained new insights into the speciation of halozincate anions in ionic liquids (ILs). Both core and valence X-ray photoelectron spectroscopy (XPS) were performed directly on the liquid-phase ILs, supplemented by Zn 1s X-ray absorption near edge structure (XANES) spectroscopy. Density functional theory (DFT) calculations were carried out on both 1- and 2- halozincate anions, in both a generalised solvation model SMD (Solvation Model based on Density) and the gas phase, to give XP spectra and total energy differences; time-dependent DFT was used to calculate XA spectra. Speciation judgements were made using a combination of the shape and width of experimental spectra, and visual matches to calculated spectra. For 2- halozincate anions, excellent matches were found between experimental and calculated XP spectra, clearly showing that only 2- halozincate anions were present at all zinc halide mole fraction, <em>x</em>, studied. At specific <em>x</em> (0.33, 0.50, 0.60) only one halozincate anion was present; equilibria of different halozincate anions at those <em>x</em> were not observed. All findings show that chlorozincate anion and bromozincate anion speciation matched at the same <em>x</em>. Based on the results, predictions are made of the halozincate anion speciation for all <em>x</em> up to 0.67. Caution is advised when using differences in calculated total energies obtained from DFT to judge halozincate anion speciation, even when the SMD was employed, as predictions based on total energy differences did not always match the findings from experimental and calculated spectra. Our findings clearly establish that the combination of high-quality experimental data from multiple spectroscopies and a wide range of calculated structures are essential to have high confidence in halozincate anion speciation identification.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanoparticles (NPs) of iron oxide are dispersed in mixtures of water and ionic liquid, here ethylammonium nitrate (EAN) and the interactions NP/NP and NP/solvent are studied. They are analysed by Small Angle X-Ray Scattering and Dynamic Light Scattering coupled to Forced Rayleigh Scattering from 22° C to 80° C. The NPs are well dispersed as individual objects on the whole range of composition and temperature thanks to a sufficient repulsion due to the organization of the solvents at the interface. The surface changes from hydrophilic to hydrophobic around a{proportion of 50 vol% of water: 50 vol% of EAN, following the evolution of the bulk mixtures, heterogeneous on the whole range of compositions.
{"title":"Dispersions of magnetic nanoparticles in Water/ Ionic Liquid mixtures","authors":"Thiago Fiuza, Mitradeep Sarkar, Jesse Cornelius Riedl, Fabrice Cousin, Gilles Demouchy, Jerome Depeyrot, Emmanuelle Dubois, Regine Perzynski, Veronique Peyre","doi":"10.1039/d4fd00028e","DOIUrl":"https://doi.org/10.1039/d4fd00028e","url":null,"abstract":"Nanoparticles (NPs) of iron oxide are dispersed in mixtures of water and ionic liquid, here ethylammonium nitrate (EAN) and the interactions NP/NP and NP/solvent are studied. They are analysed by Small Angle X-Ray Scattering and Dynamic Light Scattering coupled to Forced Rayleigh Scattering from 22° C to 80° C. The NPs are well dispersed as individual objects on the whole range of composition and temperature thanks to a sufficient repulsion due to the organization of the solvents at the interface. The surface changes from hydrophilic to hydrophobic around a{proportion of 50 vol% of water: 50 vol% of EAN, following the evolution of the bulk mixtures, heterogeneous on the whole range of compositions.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael E. Ritter, Simone Alexis DeSouza, Hannah Marie Ogden, Tara J Michael, Amy S Mullin
Collisions of optically centrifuged CO2 molecules with J=244-282 (Erot =22,800-30,300 cm-1) are investigated with high-resolution transient IR absorption spectroscopy to reveal collisional and orientational phenomena of molecules with hyper-thermal rotational energies. The optical centrifuge is a non-resonant optical excitation technique that uses ultrafast, 800 nm chirped pulses to drive molecules to extreme rotational states through sequential Raman transitions. The extent of rotational excitation is controlled by tuning the optical bandwidth of the excitation pulses. Frequencies of 30 R-branch ν_3 fundamental IR probe transitions are measured for the J=186-282 states of CO2, expanding beyond previously reported IR transitions up to J=128. The optically centrifuged molecules have oriented angular momentum and unidirectional rotation. Polarization-sensitive transient IR absorption of individual rotational states of optically centrifuged molecules and their collision products reveals information about collisional energy transfer, relaxation kinetics, and dynamics of rotation-to-translation energy transfer. The transient IR probe also measures the extent of orientation and decay rates of the orientation anisotropy. Rotational energy transfer for lower energy molecules are discussed in terms of statistical models and a comparison highlights the role of increasing energy gap with J and angular momentum of the optically centrifuged molecules.
{"title":"Transient IR Spectroscopy of Optically Centrifuged CO2 (R186−R282) and Collision Dynamics for the J=244−282 States","authors":"Michael E. Ritter, Simone Alexis DeSouza, Hannah Marie Ogden, Tara J Michael, Amy S Mullin","doi":"10.1039/d3fd00179b","DOIUrl":"https://doi.org/10.1039/d3fd00179b","url":null,"abstract":"Collisions of optically centrifuged CO<small><sub>2</sub></small> molecules with J=244-282 (E<small><sub>rot</sub></small> =22,800-30,300 cm<small><sup>-1</sup></small>) are investigated with high-resolution transient IR absorption spectroscopy to reveal collisional and orientational phenomena of molecules with hyper-thermal rotational energies. The optical centrifuge is a non-resonant optical excitation technique that uses ultrafast, 800 nm chirped pulses to drive molecules to extreme rotational states through sequential Raman transitions. The extent of rotational excitation is controlled by tuning the optical bandwidth of the excitation pulses. Frequencies of 30 R-branch ν_3 fundamental IR probe transitions are measured for the J=186-282 states of CO<small><sub>2</sub></small>, expanding beyond previously reported IR transitions up to J=128. The optically centrifuged molecules have oriented angular momentum and unidirectional rotation. Polarization-sensitive transient IR absorption of individual rotational states of optically centrifuged molecules and their collision products reveals information about collisional energy transfer, relaxation kinetics, and dynamics of rotation-to-translation energy transfer. The transient IR probe also measures the extent of orientation and decay rates of the orientation anisotropy. Rotational energy transfer for lower energy molecules are discussed in terms of statistical models and a comparison highlights the role of increasing energy gap with J and angular momentum of the optically centrifuged molecules.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Naomi Elstone, Emily Shaw, Karina Shimizu, Joshua Lai, Bruno Demé, Paul Lane, Matthew L Costen, Kenneth G McKendrick, Sarah Elizabeth Youngs, Sarah E. Rogers, Jose Nuno Canongia Lopes, Duncan W Bruce, John M. Slattery
As part of an ongoing study of the structure and properties of mixtures of ionic liquids in which one component has a hydrocarbon chain and the other a semiperfluorocarbon chain, we now report a study of the mixtures [C8MIM]1-x[C10MIM-F17]x[Tf2N], [C10MIM]1-x[C8MIM-F13]x[Tf2N] and [C10MIM]1-x[C10MIM-F17]x[Tf2N], where [C8MIM][Tf2N] is 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide, [C10MIM][Tf2N] is 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C8MIM-F13][Tf2N] is 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide and [C10MIM-F17][Tf2N] is 1-(1H,1H,2H,2H-perfluorodecyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide. The mixtures were investigated using small-angle X-ray (SAXS) and neutron (SANS) scattering complemented by molecular dynamics simulations (with viscosity and surface tension measurements also possible for the mixtures [C10MIM]1-x[C8MIM-F13]x[Tf2N]). Unlike previous studies of [C8MIM]1-x[C8MIM-F13]x[Tf2N], where no strong evidence of alkyl/fluoroalkyl chain segregation or triphilic behaviour was seen (Elstone et al., J. Phys. Chem. B, 2023, 127, 7394-7407), these new mixtures showed the formation of small aggregates of varying sizes of each component, even though all were co-miscible across the full range of compositions. Thus, while a clear polar non-polar peak (PNPP) was observed at large or small values of x, at intermediate compositions the small-angle neutron scattering at low q was dominated by scattering from these small aggregates, with little or no evidence of the PNPP at some compositions. The origins of this behaviour are discussed in terms of inter-chain interactions.
{"title":"Chain-length dependent organisation in mixtures of hydrogenous and fluorous ionic liquids","authors":"Naomi Elstone, Emily Shaw, Karina Shimizu, Joshua Lai, Bruno Demé, Paul Lane, Matthew L Costen, Kenneth G McKendrick, Sarah Elizabeth Youngs, Sarah E. Rogers, Jose Nuno Canongia Lopes, Duncan W Bruce, John M. Slattery","doi":"10.1039/d4fd00047a","DOIUrl":"https://doi.org/10.1039/d4fd00047a","url":null,"abstract":"As part of an ongoing study of the structure and properties of mixtures of ionic liquids in which one component has a hydrocarbon chain and the other a semiperfluorocarbon chain, we now report a study of the mixtures [C8MIM]1-x[C10MIM-F17]x[Tf2N], [C10MIM]1-x[C8MIM-F13]x[Tf2N] and [C10MIM]1-x[C10MIM-F17]x[Tf2N], where [C8MIM][Tf2N] is 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide, [C10MIM][Tf2N] is 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C8MIM-F13][Tf2N] is 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide and [C10MIM-F17][Tf2N] is 1-(1H,1H,2H,2H-perfluorodecyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide. The mixtures were investigated using small-angle X-ray (SAXS) and neutron (SANS) scattering complemented by molecular dynamics simulations (with viscosity and surface tension measurements also possible for the mixtures [C10MIM]1-x[C8MIM-F13]x[Tf2N]). Unlike previous studies of [C8MIM]1-x[C8MIM-F13]x[Tf2N], where no strong evidence of alkyl/fluoroalkyl chain segregation or triphilic behaviour was seen (Elstone et al., J. Phys. Chem. B, 2023, 127, 7394-7407), these new mixtures showed the formation of small aggregates of varying sizes of each component, even though all were co-miscible across the full range of compositions. Thus, while a clear polar non-polar peak (PNPP) was observed at large or small values of x, at intermediate compositions the small-angle neutron scattering at low q was dominated by scattering from these small aggregates, with little or no evidence of the PNPP at some compositions. The origins of this behaviour are discussed in terms of inter-chain interactions.","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140577198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Perspective on the Future of Quantum Chemical Software: The Example of the ORCA Program Package","authors":"Frank Neese","doi":"10.1039/d4fd00056k","DOIUrl":"https://doi.org/10.1039/d4fd00056k","url":null,"abstract":"TBC","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pierre-Francois Loos, Antoine Marie, Abdallah Ammar
The cumulant expansion of the Green’s function is a computationally efficient beyond-GW approach renowned for its significant enhancement of satellite features in materials. In contrast to the ubiquitous GW approximation of many-body perturbation theory, ab initio cumulant expansions performed on top of GW (GW+C) have demonstrated the capability to handle multi-particle processes by incorporating higher-order correlation effects or vertex corrections, yielding better agreements between experiment and theory for satellite structures. While widely employed in condensed matter physics, very few applications of GW+C have been published on molecular systems. Here, we assess the performance of this scheme on a series of 10-electron molecular systems (Ne, HF, H2O, NH3, and CH4) where full configuration interaction estimates of the outer-valence quasiparticle and satellite energies are available.
格林函数的累积展开是一种计算高效的超越全球定位系统的方法，因其显著增强了材料中的卫星特征而闻名。与多体扰动理论中无处不在的 GW 近似相比，在 GW（GW+C）基础上进行的 ab initio 积展开证明了通过纳入高阶相关效应或顶点校正来处理多粒子过程的能力，从而在卫星结构的实验与理论之间取得更好的一致。虽然 GW+C 广泛应用于凝聚态物理，但在分子系统中的应用却寥寥无几。在这里，我们评估了这一方案在一系列 10 电子分子系统（Ne、HF、H2O、NH3 和 CH4）上的性能，这些系统的外价准粒子和卫星能量的完全构型相互作用估计值是可用的。
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