Pub Date : 2026-10-20DOI: 10.1021/acs.jctc.6c01350
Er-Fei Zhen,Chen-Yu Zhang,Yan-Xia Chen
We quantify how metal identity and crystallographic orientation shape the electrical double layer (EDL) and differential capacitance (Cdl) in weakly adsorbing electrolytes. The concentration-dependent Cdl curves of Ag(110), Ag(100), Ag(111), and Au(110) in aqueous KPF6, are quantitatively analyzed using the density-potential functional theory (DPFT). The comparative analysis results in four key findings. First, in accordance with conventional understanding, Cdl is dominated by the diffuse layer and is identical for Ag and Au electrodes near their respective potential of zero free charge (pzfc) at the same low electrolyte concentrations. Second, the Cdl sequence of Ag(110)>Ag(100)>Ag(111) at their pzfc at the same higher electrolyte concentration is attributed to facet-dependent water adsorption. Third, under same solution conditions, Ag(110) shows a higher Cdl peak and smaller peak-to-peak spacing than Au(110), reflecting differences in short-range metal-water interaction, metal-ion interaction and electron spillover at the metal surface. Fourth, partial desolvation under strong interfacial fields further reshapes the ionic distribution and lifts the Cdl curves away from the pzfc. Overall, these results map macroscopic capacitance fingerprints onto microscopic EDL structure within a unified DPFT framework.
{"title":"Correlating Metal-Water Interactions and Double-Layer Capacitance at Gold and Silver: Revisit of Single-Crystal Experiments Using a Unified Theoretical Model","authors":"Er-Fei Zhen,Chen-Yu Zhang,Yan-Xia Chen","doi":"10.1021/acs.jctc.6c01350","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01350","url":null,"abstract":"We quantify how metal identity and crystallographic orientation shape the electrical double layer (EDL) and differential capacitance (Cdl) in weakly adsorbing electrolytes. The concentration-dependent Cdl curves of Ag(110), Ag(100), Ag(111), and Au(110) in aqueous KPF6, are quantitatively analyzed using the density-potential functional theory (DPFT). The comparative analysis results in four key findings. First, in accordance with conventional understanding, Cdl is dominated by the diffuse layer and is identical for Ag and Au electrodes near their respective potential of zero free charge (pzfc) at the same low electrolyte concentrations. Second, the Cdl sequence of Ag(110)>Ag(100)>Ag(111) at their pzfc at the same higher electrolyte concentration is attributed to facet-dependent water adsorption. Third, under same solution conditions, Ag(110) shows a higher Cdl peak and smaller peak-to-peak spacing than Au(110), reflecting differences in short-range metal-water interaction, metal-ion interaction and electron spillover at the metal surface. Fourth, partial desolvation under strong interfacial fields further reshapes the ionic distribution and lifts the Cdl curves away from the pzfc. Overall, these results map macroscopic capacitance fingerprints onto microscopic EDL structure within a unified DPFT framework.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"73 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jctc.6c00696
Takuma Ito,Yuki Kurashige
Properties of photofunctional materials are governed by nonadiabatic transitions, and theoretical methods to predict reaction rate constants for nonadiabatic transitions are desired. Fermi’s golden rule (FGR) is one of the most useful approaches for computing rate constants. In particular, FGR combined with the harmonic approximation to the potential energy surface (PES) is widely used, since it requires only geometry optimizations and Hessian calculations for the initial and final states. However, real PESs are inherently anharmonic, and such anharmonicity can affect the rate constant by altering vibrational energy levels and wave functions. In this study, we propose a method for computing rate constants that incorporates anharmonicity into the conventional harmonic-approximation framework. In this method, only a subset of important modes is treated anharmonically, whereas the remaining modes are treated harmonically. We applied the proposed method to two systems: the T1 → S0 nonradiative decay process of 4-pyrone molecule, and the S1 → T1 intersystem crossing process of 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN) molecule. The calculation for 4-pyrone revealed that the rate constant decreases by 3 orders of magnitude compared with the harmonic rate when anharmonicity of all vibrational modes is taken into account, indicating the importance of considering the anharmonicity when calculating the rate constant. In addition, it was found that the fully anharmonic rate constant can be reproduced by considering the anharmonicity of only two vibrational modes. Further analysis based on the sum-over-states formalism revealed that this decrease in the rate constant originates from a reduction in the overlaps between the initial- and final-state vibrational eigenfunctions. It was also found that this decrease in the rate constant does not appear unless the anharmonicity of multiple vibrational modes is taken into account simultaneously, even though coupling between vibrational modes is not considered. The application to ACRXTN showed that the anharmonicity associated with dihedral torsional modes has little influence on the rate constant. Comparison of these results revealed that the anharmonicity of vibrational modes with high Huang–Rhys factors and high frequencies, or those whose harmonic frequencies are different between initial and final states, has an impact on the rate constant. The proposed method is expected to be useful for the theoretical design of new photofunctional materials.
{"title":"Incorporating Anharmonicity of Selected Modes into Fermi’s Golden Rule Rate Calculations for Large Molecular Systems","authors":"Takuma Ito,Yuki Kurashige","doi":"10.1021/acs.jctc.6c00696","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c00696","url":null,"abstract":"Properties of photofunctional materials are governed by nonadiabatic transitions, and theoretical methods to predict reaction rate constants for nonadiabatic transitions are desired. Fermi’s golden rule (FGR) is one of the most useful approaches for computing rate constants. In particular, FGR combined with the harmonic approximation to the potential energy surface (PES) is widely used, since it requires only geometry optimizations and Hessian calculations for the initial and final states. However, real PESs are inherently anharmonic, and such anharmonicity can affect the rate constant by altering vibrational energy levels and wave functions. In this study, we propose a method for computing rate constants that incorporates anharmonicity into the conventional harmonic-approximation framework. In this method, only a subset of important modes is treated anharmonically, whereas the remaining modes are treated harmonically. We applied the proposed method to two systems: the T1 → S0 nonradiative decay process of 4-pyrone molecule, and the S1 → T1 intersystem crossing process of 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN) molecule. The calculation for 4-pyrone revealed that the rate constant decreases by 3 orders of magnitude compared with the harmonic rate when anharmonicity of all vibrational modes is taken into account, indicating the importance of considering the anharmonicity when calculating the rate constant. In addition, it was found that the fully anharmonic rate constant can be reproduced by considering the anharmonicity of only two vibrational modes. Further analysis based on the sum-over-states formalism revealed that this decrease in the rate constant originates from a reduction in the overlaps between the initial- and final-state vibrational eigenfunctions. It was also found that this decrease in the rate constant does not appear unless the anharmonicity of multiple vibrational modes is taken into account simultaneously, even though coupling between vibrational modes is not considered. The application to ACRXTN showed that the anharmonicity associated with dihedral torsional modes has little influence on the rate constant. Comparison of these results revealed that the anharmonicity of vibrational modes with high Huang–Rhys factors and high frequencies, or those whose harmonic frequencies are different between initial and final states, has an impact on the rate constant. The proposed method is expected to be useful for the theoretical design of new photofunctional materials.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"42 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jctc.6c01592
Vedran Miletić,Miłosz Wieczór,Carlos Simmerling,Markus Rampp,Bert L. de Groot,Carsten Kutzner,Vytautas Gapsys
The GROMACS molecular dynamics simulation package has historically supported a number of molecular mechanics force fields, including Amber. Force fields have evolved over time and continue to do so through refinement of existing interactions and the definition of additional ones to more faithfully match real-world experiments and higher-level quantum chemistry calculations. Although users have provided a number of conversions of newer Amber force fields over the years, the two most recent Amber protein force fields, ff14SB and ff19SB, had not previously been officially ported to GROMACS. A technical challenge is that ff19SB introduces residue-specific backbone dihedral energy correction maps (CMAPs), which required new support in GROMACS for residue-aware force-field preprocessing and topology generation. Unlike older force fields such as CHARMM27, in which CMAPs are parameterized using only atom types, ff19SB extends this scheme with additional amino-acid typing. Here, we describe how we ported and validated the Amber ff14SB and ff19SB force fields for use with GROMACS as AMBER14SB and AMBER19SB, respectively. The ported force fields reproduce the Amber reference topologies exactly, with per-interaction energies matching to within the single-precision floating-point limit (<10–7 kJ/mol). To achieve this level of consistency between Amber and GROMACS, we resolved discrepancies in their handling of fundamental constants, parameter precision, and improper-dihedral atom ordering logic. In long unrestrained ubiquitin simulations, the converted ff19SB reproduces the conformational free-energy profile obtained with the native Amber implementation. This work provides the first official port of an Amber force field to GROMACS in more than a decade, improving feature parity between the two simulation packages. We provide a reproducible porting and validation procedure that can be used for modified variants and future versions of Amber force fields.
{"title":"Force Fields and Simulation Engines: Lessons Learned from Porting Amber ff14SB and ff19SB to GROMACS","authors":"Vedran Miletić,Miłosz Wieczór,Carlos Simmerling,Markus Rampp,Bert L. de Groot,Carsten Kutzner,Vytautas Gapsys","doi":"10.1021/acs.jctc.6c01592","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01592","url":null,"abstract":"The GROMACS molecular dynamics simulation package has historically supported a number of molecular mechanics force fields, including Amber. Force fields have evolved over time and continue to do so through refinement of existing interactions and the definition of additional ones to more faithfully match real-world experiments and higher-level quantum chemistry calculations. Although users have provided a number of conversions of newer Amber force fields over the years, the two most recent Amber protein force fields, ff14SB and ff19SB, had not previously been officially ported to GROMACS. A technical challenge is that ff19SB introduces residue-specific backbone dihedral energy correction maps (CMAPs), which required new support in GROMACS for residue-aware force-field preprocessing and topology generation. Unlike older force fields such as CHARMM27, in which CMAPs are parameterized using only atom types, ff19SB extends this scheme with additional amino-acid typing. Here, we describe how we ported and validated the Amber ff14SB and ff19SB force fields for use with GROMACS as AMBER14SB and AMBER19SB, respectively. The ported force fields reproduce the Amber reference topologies exactly, with per-interaction energies matching to within the single-precision floating-point limit (<10–7 kJ/mol). To achieve this level of consistency between Amber and GROMACS, we resolved discrepancies in their handling of fundamental constants, parameter precision, and improper-dihedral atom ordering logic. In long unrestrained ubiquitin simulations, the converted ff19SB reproduces the conformational free-energy profile obtained with the native Amber implementation. This work provides the first official port of an Amber force field to GROMACS in more than a decade, improving feature parity between the two simulation packages. We provide a reproducible porting and validation procedure that can be used for modified variants and future versions of Amber force fields.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"13 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rational design of lithium-ion battery (LIB) electrolytes is severely impeded by the vast chemical space of solvent–salt combinations and the inefficiency of empirical trial-and-error approaches. Molecular dynamics (MD) bridges microscopic solvation structures and macroscopic physicochemical properties, but classical force fields (FFs) often lack accuracy for multicomponent electrolytes. To address this, we develop an automated differentiable OPLS-AA FF parametrization workflow tailored for ionic electrolytes. It employs topology-guided atom typing to reduce parameter redundancy and optimizes Lennard-Jones parameters via the DMFF framework. A uniform charge-scaling scheme approximates condensed-phase charge transfer and polarization. Density serves as the structural/thermodynamic fitting target, while ionic conductivity provides the independent transport benchmark, ensuring balanced accuracy. Rigorous convergence tests establish a standardized protocol with ∼100,000-atom systems and 35–40 ns NVT trajectories for reliable transport property calculations. Furthermore, high-throughput simulations of over 10,000 formulations─encompassing 67 solvents and 15 lithium salts─are performed on Tianqiong, a special-purpose supercomputer for molecular dynamics simulations that has been validated to deliver numerically equivalent results to GPUs with superior efficiency. A comprehensive data set is generated covering five key electrolyte properties. The t-SNE visualization reveals partial clustering of distinct salt chemistries, continuous property gradients as functions of salt concentration and temperature, and internal physical self-consistency across the measured electrolyte parameters while simultaneously identifying solvent components as another critical performance determinant. The accurate, transferable FF and the rich data resource establish a robust foundation for future data-driven design of ionic electrolytes.
{"title":"Differentiable OPLS Force-Field Parameterization for Ionic Electrolytes and High-Throughput Application to Lithium-Ion Batteries","authors":"Haichao Huang,Zilin Chen,Qi Liu,Tianqi Zhao,Yunpei Liu,Guotao Qiu,Jianhui Chen,Zhen Li,Wenshuo Liang,Minsung Cho,Manxue Zhang,Feiyu Kang,Xiaolong Zou,Yidan Cao,Xushan Zhao,Ziqi Cheng,Ye Mei","doi":"10.1021/acs.jctc.6c01451","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01451","url":null,"abstract":"The rational design of lithium-ion battery (LIB) electrolytes is severely impeded by the vast chemical space of solvent–salt combinations and the inefficiency of empirical trial-and-error approaches. Molecular dynamics (MD) bridges microscopic solvation structures and macroscopic physicochemical properties, but classical force fields (FFs) often lack accuracy for multicomponent electrolytes. To address this, we develop an automated differentiable OPLS-AA FF parametrization workflow tailored for ionic electrolytes. It employs topology-guided atom typing to reduce parameter redundancy and optimizes Lennard-Jones parameters via the DMFF framework. A uniform charge-scaling scheme approximates condensed-phase charge transfer and polarization. Density serves as the structural/thermodynamic fitting target, while ionic conductivity provides the independent transport benchmark, ensuring balanced accuracy. Rigorous convergence tests establish a standardized protocol with ∼100,000-atom systems and 35–40 ns NVT trajectories for reliable transport property calculations. Furthermore, high-throughput simulations of over 10,000 formulations─encompassing 67 solvents and 15 lithium salts─are performed on Tianqiong, a special-purpose supercomputer for molecular dynamics simulations that has been validated to deliver numerically equivalent results to GPUs with superior efficiency. A comprehensive data set is generated covering five key electrolyte properties. The t-SNE visualization reveals partial clustering of distinct salt chemistries, continuous property gradients as functions of salt concentration and temperature, and internal physical self-consistency across the measured electrolyte parameters while simultaneously identifying solvent components as another critical performance determinant. The accurate, transferable FF and the rich data resource establish a robust foundation for future data-driven design of ionic electrolytes.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jctc.6c01398
Sebastian R. Thomsen,Anker M. H. Nielsen,Bo B. Iversen,Frank Jensen
Electron densities provide valuable information, such as atomic charges and static structure factors, but all-electron densities can be computationally expensive to obtain. This work presents a method to approximate all-electron densities from pseudopotential electronic structure calculations, called the Valence Electrons Plus Independent Cores (VEPIC) model. For each pseudopotential in the calculation, a pseudocore is defined, and this is added to the ab initio pseudovalence density. Electron densities obtained this way yield accurate static structure factors, as well as atomic charges and dipoles from the Hirshfeld and Minimal Basis Iterative Stockholder methods, compared with those from all-electron calculations. While the total density of this model matches the all-electron density in the valence region, the model lacks core polarization, which is present in the Projector Augmented Wave (PAW) method, making the VEPIC model an intermediate between the Independent Atom Model (IAM) and the PAW model in terms of accuracy. It is also intermediate between the two in terms of computational complexity, as it only requires the pseudovalence density, unlike PAW, which additionally requires processing every pseudovalence wave function in the system.
{"title":"Reconstructing All-Electron Densities and Static Structure Factors from General Pseudopotentials","authors":"Sebastian R. Thomsen,Anker M. H. Nielsen,Bo B. Iversen,Frank Jensen","doi":"10.1021/acs.jctc.6c01398","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01398","url":null,"abstract":"Electron densities provide valuable information, such as atomic charges and static structure factors, but all-electron densities can be computationally expensive to obtain. This work presents a method to approximate all-electron densities from pseudopotential electronic structure calculations, called the Valence Electrons Plus Independent Cores (VEPIC) model. For each pseudopotential in the calculation, a pseudocore is defined, and this is added to the ab initio pseudovalence density. Electron densities obtained this way yield accurate static structure factors, as well as atomic charges and dipoles from the Hirshfeld and Minimal Basis Iterative Stockholder methods, compared with those from all-electron calculations. While the total density of this model matches the all-electron density in the valence region, the model lacks core polarization, which is present in the Projector Augmented Wave (PAW) method, making the VEPIC model an intermediate between the Independent Atom Model (IAM) and the PAW model in terms of accuracy. It is also intermediate between the two in terms of computational complexity, as it only requires the pseudovalence density, unlike PAW, which additionally requires processing every pseudovalence wave function in the system.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"46 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jctc.6c01004
Nicolas Grimblat,Gabriel Klassen,Guido Falk von Rudorff
Quantum chemistry calculations are often performed using atom-centered basis sets, which are chosen to balance accuracy and cost. While they are systematically improvable, the total energy converges slowly with basis set size toward the complete basis set (CBS) limit. Common extrapolation methods require several intermediate-quality calculations to afford an estimate of the CBS energy. We propose a minimal complementary auxiliary basis set (CABS) baseline to estimate the CBS energy from a single quantum chemistry calculation in a minimal basis set via kernel ridge regression (KRR), which is more efficient than both direct and Δ-machine learning and 40× faster than triple-ζ single-point calculations. The spatial and alchemical gradients from minimal basis and minimal CABS are more accurate than double-ζ (DZ) calculations. We show that KRR on standard molecular representations can be improved by approximating atom-wise local kernels using Chebyshev polynomials, which allows us to train KRR models 10×–50× times faster on moderate compute resources, thereby enabling a data-driven approach toward the mean-field CBS, combining physical baselines capturing leading-order effects with data-efficient machine learning models.
{"title":"Data-Driven Complete Basis Set Limit Estimates from a Minimal Auxiliary Basis","authors":"Nicolas Grimblat,Gabriel Klassen,Guido Falk von Rudorff","doi":"10.1021/acs.jctc.6c01004","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01004","url":null,"abstract":"Quantum chemistry calculations are often performed using atom-centered basis sets, which are chosen to balance accuracy and cost. While they are systematically improvable, the total energy converges slowly with basis set size toward the complete basis set (CBS) limit. Common extrapolation methods require several intermediate-quality calculations to afford an estimate of the CBS energy. We propose a minimal complementary auxiliary basis set (CABS) baseline to estimate the CBS energy from a single quantum chemistry calculation in a minimal basis set via kernel ridge regression (KRR), which is more efficient than both direct and Δ-machine learning and 40× faster than triple-ζ single-point calculations. The spatial and alchemical gradients from minimal basis and minimal CABS are more accurate than double-ζ (DZ) calculations. We show that KRR on standard molecular representations can be improved by approximating atom-wise local kernels using Chebyshev polynomials, which allows us to train KRR models 10×–50× times faster on moderate compute resources, thereby enabling a data-driven approach toward the mean-field CBS, combining physical baselines capturing leading-order effects with data-efficient machine learning models.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jctc.6c01519
Francisco García-González,Julia Portela-Pino,Daniel Aranda,José Lorenzo Alonso-Gómez,Fabrizio Santoro
The chiroptical response of π-conjugated macrocycles assembled from repeating chromophores can be remarkably intense, yet how it scales with ring size, and what controls it, remains only partly understood. Here we investigate a series of axially chiral diethynylspirobifluorene macrocycles, (Pn)-DESn (n = 2, 3, 4; D2, D3 and D4 symmetry), combining accurate nonadiabatic quantum dynamics with two complementary linear vibronic coupling Hamiltonians: a delocalized model, whose diabatic states span the whole macrocycle, and a localized, exciton-like model built from the excitations of the individual fragments. Both reproduce the experimental one-photon absorption and electronic circular dichroism (ECD) spectra and reveal that nonadiabatic interactions, conical intersections and (pseudo-)Jahn–Teller couplings govern their shapes; a hierarchical representation of the Hamiltonian keeps the simulations tractable, even for (P4)-DES4, with more than 500 vibrational modes. A simple symmetry analysis bridges the two pictures, tracing every coupling back to the single excited-state gradient of the monomer and partitions the magnetic transition dipole into an intrinsic contribution, from the strained monomer and an extrinsic, excitonic one. This decomposition rationalizes the observed trends explaining why the ECD grows super-linearly with ring size. As a result, the response crosses over from strain-dominated chirality in (P2)-DES2 to excitonic chirality in (P4)-DES4 at a nearly constant dissymmetry factor. Crucially, the excitonic rotatory strengths form a nearly conservative couplet whose oppositely signed branches partly cancel, and their splitting (0.12–0.16 eV) is comparable to the width of the vibronic progressions. The intrinsic band shape of the monomer, not the splitting alone, therefore sets how much ECD survives. We translate these findings into geometric, excitonic and vibronic design principles for g-factor improved symmetric chiral macrocycles, suggesting that our proposed computational approach can be a fast screening tool for new designed macrocycles before synthesis.
{"title":"Localized and Delocalized Nonadiabatic Vibronic Models Unravel Chiroptical Trends and Design Principles in Symmetric π Conjugated Macrocycles","authors":"Francisco García-González,Julia Portela-Pino,Daniel Aranda,José Lorenzo Alonso-Gómez,Fabrizio Santoro","doi":"10.1021/acs.jctc.6c01519","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01519","url":null,"abstract":"The chiroptical response of π-conjugated macrocycles assembled from repeating chromophores can be remarkably intense, yet how it scales with ring size, and what controls it, remains only partly understood. Here we investigate a series of axially chiral diethynylspirobifluorene macrocycles, (Pn)-DESn (n = 2, 3, 4; D2, D3 and D4 symmetry), combining accurate nonadiabatic quantum dynamics with two complementary linear vibronic coupling Hamiltonians: a delocalized model, whose diabatic states span the whole macrocycle, and a localized, exciton-like model built from the excitations of the individual fragments. Both reproduce the experimental one-photon absorption and electronic circular dichroism (ECD) spectra and reveal that nonadiabatic interactions, conical intersections and (pseudo-)Jahn–Teller couplings govern their shapes; a hierarchical representation of the Hamiltonian keeps the simulations tractable, even for (P4)-DES4, with more than 500 vibrational modes. A simple symmetry analysis bridges the two pictures, tracing every coupling back to the single excited-state gradient of the monomer and partitions the magnetic transition dipole into an intrinsic contribution, from the strained monomer and an extrinsic, excitonic one. This decomposition rationalizes the observed trends explaining why the ECD grows super-linearly with ring size. As a result, the response crosses over from strain-dominated chirality in (P2)-DES2 to excitonic chirality in (P4)-DES4 at a nearly constant dissymmetry factor. Crucially, the excitonic rotatory strengths form a nearly conservative couplet whose oppositely signed branches partly cancel, and their splitting (0.12–0.16 eV) is comparable to the width of the vibronic progressions. The intrinsic band shape of the monomer, not the splitting alone, therefore sets how much ECD survives. We translate these findings into geometric, excitonic and vibronic design principles for g-factor improved symmetric chiral macrocycles, suggesting that our proposed computational approach can be a fast screening tool for new designed macrocycles before synthesis.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-18DOI: 10.1021/acs.jctc.6c01476
Dávid Mester,Mihály Kállay
Abstract Two-photon absorption (2PA) strengths span several orders of magnitude, yet time-dependent density functional theory (TDDFT) benchmark studies have commonly relied on raw-scale mean absolute errors and linear regression statistics. Such statistics can be dominated by the most intense transitions and do not distinguish systematic multiplicative bias, typical fold error, dynamic range reproduction, and rank preservation. Here, published TDDFT 2PA benchmarks based on coupled-cluster references are reanalyzed by using a scale-invariant, multiplicative framework. For the most widely used benchmark set [J. Chem.Theory Comput. 2022, 18, 1046], it is shown that the five strongest transitions, representing only approximately 10% of the data, account for up to 65.5% of the total raw absolute error. Consequently, raw-scale metrics assign disproportionate weight to a small number of intense transitions and may obscure method performance across the remainder of the intensity range. Across several benchmark sets, the analysis further reveals that similar raw-scale errors can arise from qualitatively different error structures. The multiplicative analysis goes beyond previously recognized qualitative trends by resolving them into directly comparable and interpretable components. These results demonstrate that neither individual raw-scale metrics nor their combinations provide a sufficient basis for identifying a reliable or generally recommended functional, and they support a multidimensional, scale-invariant assessment of 2PA benchmarks. The same framework may also be useful for other properties for which multiplicative errors provide a more appropriate description than additive deviations such as oscillator strengths, kinetic and radiative rate constants, and equilibrium constants.
{"title":"Multiplicative\u0000Error Analysis: A Scale-Invariant View\u0000of TDDFT Two-Photon Absorption Benchmarks","authors":"Dávid Mester,Mihály Kállay","doi":"10.1021/acs.jctc.6c01476","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01476","url":null,"abstract":"Abstract Two-photon absorption (2PA) strengths span several orders of magnitude, yet time-dependent density functional theory (TDDFT) benchmark studies have commonly relied on raw-scale mean absolute errors and linear regression statistics. Such statistics can be dominated by the most intense transitions and do not distinguish systematic multiplicative bias, typical fold error, dynamic range reproduction, and rank preservation. Here, published TDDFT 2PA benchmarks based on coupled-cluster references are reanalyzed by using a scale-invariant, multiplicative framework. For the most widely used benchmark set [J. Chem.Theory Comput. 2022, 18, 1046], it is shown that the five strongest transitions, representing only approximately 10% of the data, account for up to 65.5% of the total raw absolute error. Consequently, raw-scale metrics assign disproportionate weight to a small number of intense transitions and may obscure method performance across the remainder of the intensity range. Across several benchmark sets, the analysis further reveals that similar raw-scale errors can arise from qualitatively different error structures. The multiplicative analysis goes beyond previously recognized qualitative trends by resolving them into directly comparable and interpretable components. These results demonstrate that neither individual raw-scale metrics nor their combinations provide a sufficient basis for identifying a reliable or generally recommended functional, and they support a multidimensional, scale-invariant assessment of 2PA benchmarks. The same framework may also be useful for other properties for which multiplicative errors provide a more appropriate description than additive deviations such as oscillator strengths, kinetic and radiative rate constants, and equilibrium constants.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"21 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-16DOI: 10.1021/acs.jctc.6c01605
Giovanni Cistaro,Miguel Sá,Davide Sangalli,Antonio Picón,Nicola Colonna
Abstract We present an efficient first-principles approach for simulating the nonequilibrium electron dynamics in extended systems beyond the linear regime. The method combines Koopmans-compliant functionals, which provide accurate quasiparticle band structures, with the real-time evolution of the electronic density matrix in a Wannier basis within the Hartree plus screened exchange (HSEX) approximation. The locality of the orbital basis enables physically motivated approximations that significantly reduce both the computational cost and memory requirements while preserving accuracy. The screened Coulomb interaction, the central ingredient of the HSEX self-energy, is computed efficiently using density-functional perturbation theory. We benchmark the approach in the linear regime against experimental spectra and reference Green’s function calculations for systems featuring both weakly and strongly bound excitons. Moving to the nonlinear regime, we investigate high-harmonic generation in silicon and lithium fluoride. While in silicon the HHG spectrum is largely governed by the quasiparticle band structure, in LiF, a material featuring strong excitonic effects, the harmonic emission is selectively enhanced at excitonic resonances, suggesting that HHG probes correlated electron–hole excitations rather than solely the quasiparticle band structure. The present framework enables fully ab initio simulations of excitonic effects in nonlinear optical spectra at a significantly reduced computational cost compared to real-time Green’s function approaches, providing an efficient route to the study of ultrafast and strong-field phenomena in solids.
{"title":"Efficient Nonequilibrium\u0000Electron Dynamics from First-Principles:\u0000Leveraging Koopmans Spectral Functionals and Wannier Localization","authors":"Giovanni Cistaro,Miguel Sá,Davide Sangalli,Antonio Picón,Nicola Colonna","doi":"10.1021/acs.jctc.6c01605","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01605","url":null,"abstract":"Abstract We present an efficient first-principles approach for simulating the nonequilibrium electron dynamics in extended systems beyond the linear regime. The method combines Koopmans-compliant functionals, which provide accurate quasiparticle band structures, with the real-time evolution of the electronic density matrix in a Wannier basis within the Hartree plus screened exchange (HSEX) approximation. The locality of the orbital basis enables physically motivated approximations that significantly reduce both the computational cost and memory requirements while preserving accuracy. The screened Coulomb interaction, the central ingredient of the HSEX self-energy, is computed efficiently using density-functional perturbation theory. We benchmark the approach in the linear regime against experimental spectra and reference Green’s function calculations for systems featuring both weakly and strongly bound excitons. Moving to the nonlinear regime, we investigate high-harmonic generation in silicon and lithium fluoride. While in silicon the HHG spectrum is largely governed by the quasiparticle band structure, in LiF, a material featuring strong excitonic effects, the harmonic emission is selectively enhanced at excitonic resonances, suggesting that HHG probes correlated electron–hole excitations rather than solely the quasiparticle band structure. The present framework enables fully ab initio simulations of excitonic effects in nonlinear optical spectra at a significantly reduced computational cost compared to real-time Green’s function approaches, providing an efficient route to the study of ultrafast and strong-field phenomena in solids.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"233 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-16DOI: 10.1021/acs.jctc.6c01369
Valay Agarawal,Bhavnesh Jangid,Rishu Khurana,Cong Liu,Christopher Knight,Matthew R. Hermes,Laura Gagliardi
Abstract Iron–sulfur clusters play central roles in biological photosynthesis, respiration, and catalysis. The [Fe4S4(SCH3)4]2– cluster possesses a dense manifold of low-lying electronic states arising from strong magnetic interactions among the Fe centers, making its electronic structure challenging to describe theoretically. Previous multireference studies have generally optimized excited states individually while neglecting the interactions among low-lying states. In this work, we investigate the low-lying electronic states of [Fe4S4(SCH3)4]2– using localized active space state interaction singles (LASSIS) combined with pair-density functional theory (PDFT). By treating all states within a common model-space Hamiltonian, LASSIS generates a single set of orthogonal low-lying states. The resulting spin-state energies organize into distinct manifolds. The same overall pattern is obtained for active spaces ranging from 22 electrons in 20 orbitals to 54 electrons in 36 orbitals. To enable these calculations, we also implement GPU acceleration for the most computationally demanding components of the LASSIS workflow.
{"title":"Spin Manifolds\u0000in the [Fe4S4(SCH3)4]2– Cluster from Localized\u0000Active Space State Interaction Singles and Pair-Density Functional\u0000Theory","authors":"Valay Agarawal,Bhavnesh Jangid,Rishu Khurana,Cong Liu,Christopher Knight,Matthew R. Hermes,Laura Gagliardi","doi":"10.1021/acs.jctc.6c01369","DOIUrl":"https://doi.org/10.1021/acs.jctc.6c01369","url":null,"abstract":"Abstract Iron–sulfur clusters play central roles in biological photosynthesis, respiration, and catalysis. The [Fe4S4(SCH3)4]2– cluster possesses a dense manifold of low-lying electronic states arising from strong magnetic interactions among the Fe centers, making its electronic structure challenging to describe theoretically. Previous multireference studies have generally optimized excited states individually while neglecting the interactions among low-lying states. In this work, we investigate the low-lying electronic states of [Fe4S4(SCH3)4]2– using localized active space state interaction singles (LASSIS) combined with pair-density functional theory (PDFT). By treating all states within a common model-space Hamiltonian, LASSIS generates a single set of orthogonal low-lying states. The resulting spin-state energies organize into distinct manifolds. The same overall pattern is obtained for active spaces ranging from 22 electrons in 20 orbitals to 54 electrons in 36 orbitals. To enable these calculations, we also implement GPU acceleration for the most computationally demanding components of the LASSIS workflow.","PeriodicalId":45,"journal":{"name":"Journal of Chemical Theory and Computation","volume":"487 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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