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This article compares two double-hybrid density functionals, r2SCAN-QIDH and SOS1-r2SCAN-QIDH-D4, and explains their terminology. The r2SCAN-QIDH model is a nonempirical DH model derived from adiabatic-connection formalism and second-order perturbation theory, while the SOS1-r2SCAN-QIDH-D4 model includes an empirical dispersion term. The article evaluates the performance of these models on different benchmark datasets and finds that the r2SCAN-QIDH model is accurate, while the dispersion-corrected variant is more efficient for noncovalent interactions. The article emphasizes the importance of using accurate terminology to avoid confusion between different DH approaches. The document also discusses the development of NL and D4 dispersion correction parameters for noncovalent interactions, providing tables with data from the GMTKN55 database. [Extracted from the article]

We develop and validate the SOS1-RSX-QIDH density functional, a one-parameter spin-opposite-scaled variant of the range-separated-exchange quadratic-integrand double-hybrid (RSX-QIDH) model. By entering into the family of spin-biased double hybrids, this new density functional benefits from an improved computational scaling that rivals with the one of hybrids, still conserving the accuracy of its RSX-QIDH version. As part of the latter family, this density functional is well-adapted to treat molecular systems that are particularly prone to self-interaction errors in their ground and excited states. In particular, we show that the SOS1-RSX-QIDH model is a good compromise to treat ground-state problems dealing with kinetics and has a real added value when applied to the evaluation of the excited-state properties of equilibrium and out-of-equilibrium molecular complexes. Even if spin-biased double hybrids are recognized to strongly underestimate noncovalent interactions, we notice and recommend coupling SOS1-RSX-QIDH with a nonlocal van der Waals potential, a combination that is here proved to compete with the best density-functional approximations currently in use. [ABSTRACT FROM AUTHOR]

The evaluation of oxidation and reduction potentials is a pivotal task in various chemical fields. However, their accurate prediction by theoretical computations, which is a complementary task and sometimes the only alternative to experimental measurement, may be often resource‐intensive and time‐consuming. This paper addresses this challenge through the application of machine learning techniques, with a particular focus on graph‐based methods (such as graph edit distances, graph kernels, and graph neural networks) that are reviewed to enlighten their deep links with theoretical chemistry. To this aim, we establish the ORedOx159 database, a comprehensive, homogeneous (with reference values stemming from density functional theory calculations), and reliable resource containing 318 one‐electron reduction and oxidation reactions and featuring 159 large organic compounds. Subsequently, we provide an instructive overview of the good practice in machine learning and of commonly utilized machine learning models. We then assess their predictive performances on the ORedOx159 dataset through extensive analyses. Our simulations using descriptors that are computed in an almost instantaneous way result in a notable improvement in prediction accuracy, with mean absolute error (MAE) values equal to 5.6 kcal mol−1 for reduction and 7.2 kcal mol−1 for oxidation potentials, which paves a way toward efficient in silico design of new electrochemical systems. [ABSTRACT FROM AUTHOR]

A combination of electrochemical, spectroscopic, computational, and kinetic studies has been used to elucidate the key mechanistic aspects of the previously reported enantioselective iminium ion trapping of photochemically generated carbon-centered radicals. The process, which provides a direct way to forge quaternary stereocenters with high fidelity, relies on the interplay of two distinct catalytic cycles: the aminocatalytic electron-relay system, which triggers the stereoselective radical trap upon iminium ion formation, and the photoredox cycle, which generates radicals under mild conditions. Critical to reaction development was the use of a chiral amine catalyst, bearing a redox-active carbazole unit, which could rapidly reduce the highly reactive and unstable intermediate generated upon radical interception. The carbazole unit, however, is also involved in another step of the electron-relay mechanism: the transiently generated carbazole radical cation acts as an oxidant to return the photocatalyst into the original state. By means of kinetic and spectroscopic studies, we have identified the last redox event as being the turnover-limiting step of the overall process. This mechanistic framework is corroborated by the linear correlation between the reaction rate and the reduction potential of the carbazole unit tethered to the aminocatalyst. The redox properties of the carbazole unit can thus be rationally tuned to improve catalytic activity. This knowledge may open a path for the mechanistically driven design of the next generation of electron-relay catalysts.

In this Communication, we assess a panel of 18 double-hybrid density functionals for the modeling of the thermochemical and kinetic properties of an extended dataset of 449 organic chemistry reactions belonging to the BH9 database. We show that most of DHs provide a statistically robust performance to model barrier height and reaction energies in reaching the "chemical accuracy." In particular, we show that nonempirical DHs, such as PBE0-DH and PBE-QIDH, or minimally parameterized alternatives, such as ωB2PLYP and B2K-PLYP, succeed to accurately model both properties in a balanced fashion. We demonstrate, however, that parameterized approaches, such as ωB97X-2 or DSD-like DHs, are more biased to only one of both properties. [ABSTRACT FROM AUTHOR]

This document is a preface for a virtual special issue of the Journal of Computational Chemistry (JCC) celebrating the 60th birthday and scientific career of Carlo Adamo. Carlo is a theoretical chemist who has made significant contributions to the field, particularly in the development of Density Functional Theory (DFT) and the PBE0 functional. He has published extensively and has been recognized for his research excellence. In addition to his scientific pursuits, Carlo is also passionate about mountaineering and has maintained long-standing collaborations and friendships throughout his career. The preface expresses gratitude to all contributors and provides a brief overview of Carlo's background and achievements. [Extracted from the article]

We recently derived a new and simple route to the determination of the range-separation parameter in range-separated exchange hybrid and double-hybrid density functionals by imposing an additional constraint to the exchange-correlation energy to recover the total energy of the hydrogen atom [Brémond et al., J. Chem. Phys. 15, 201102 (2019)]. Here, we thoroughly assess this choice by statistically comparing the derived values of the range-separation parameters to the ones obtained using the optimal tuning (OT) approach. We show that both approaches closely agree, thus, confirming the reliability of ours. We demonstrate that it provides very close performances in the computation of properties particularly prone to the one- and many-electron self-interaction errors (i.e., ionization potentials). Our approach arises as an alternative to the OT procedure, conserving the accuracy and efficiency of a standard Kohn–Sham approach to density-functional theory computation. [ABSTRACT FROM AUTHOR]

In this communication, we present a new and simple route to derive range-separated exchange (RSX) hybrid and double hybrid density functionals in a nonempirical fashion. In line with our previous developments [Brémond et al., J. Chem. Theory Comput. 14, 4052 (2018)], we show that by imposing an additional physical constraint to the exchange-correlation energy, i.e., by enforcing to reproduce the total energy of the hydrogen atom, we are able to generalize the nonempirical determination of the range-separation parameter to a family of RSX hybrid density functionals. The success of the resulting models is illustrated by an accurate modeling of several molecular systems and properties, like ionization potentials, particularly prone to the one- and many-electron self-interaction errors. [ABSTRACT FROM AUTHOR]

The recent synthesis of a C18 monocyclic ring constitutes a major breakthrough as a new all-carbon disclosed form. However, modern density functional theory approaches do not lead to the correct experimental polyynic structure and favor the cumulenic one instead. We demonstrate here that this serious drawback can be solved by recently developed range-separated nonempirical schemes, independently of which kind of functional is being applied (i.e., semilocal, hybrid, or double-hybrid). [ABSTRACT FROM AUTHOR]

PBEpow is a power series extension of the Perdew-Burke-Ernzerhof (PBE) exchange generalized gradient approximation. This novel variant is constructed by an inductive determination of the power series coefficients to fulfill physical fundamental constants in the slowly and rapidly varying density limits. When combined with the PBE correlation, PBEpow significantly improves the estimation of molecular covalent interactions such as energies of atomization reactions and keeps the line of performance of PBE for noncovalent interactions. More generally this work provides new insights about how to improve the modeling of short- and long-range interactions at the generalized gradient approximation level without the help of any kind of empirical parameterization. [ABSTRACT FROM AUTHOR]

The article titled "Are Redox-Active Centers Bridged by Saturated Flexible Linkers Systematically Electrochemically Independent?" explores the reorganization of redox-active bipartite molecules under the influence of London dispersion forces. This reorganization promotes through-space orbital overlap between electrophoric subunits, leading to the formation of prototypical cyclomers through a reductive process. The study highlights the concept of electrochemistry extending beyond covalent bonds. The details of the research are provided in the Research Article authored by Éric Brémond, Magdaléna Hromadová, Philippe P. Lainé, and others. [Extracted from the article]

This article, published in Angewandte Chemie International Edition, discusses the reorganization of redox-active bipartite molecules under the influence of London dispersion forces. This reorganization allows for through-space orbital overlap between the electrophoric subunits, leading to the formation of prototypical cyclomers through a reductive process. The study highlights the concept of electrochemistry extending beyond covalent bonds. The details of the study can be found in the Research Article by Éric Brémond, Magdaléna Hromadová, Philippe P. Lainé, and others. [Extracted from the article]

We propose two analytical expressions aiming to rationalize the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) schemes for double-hybrid exchange-correlation density-functionals. Their performances are extensively tested within the framework of the nonempirical quadratic integrand double-hybrid (QIDH) model on energetic properties included into the very large GMTKN30 benchmark database, and on structural properties of semirigid medium-sized organic compounds. The SOS variant is revealed as a less computationally demanding alternative to reach the accuracy of the original QIDH model without losing any theoretical background. [ABSTRACT FROM AUTHOR]