Toward the Next Generation of Density Functionals: Escaping the Zero-Sum Game by Using the Exact-Exchange Energy Density

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(13), P. 1815 - 1826

Published: June 21, 2024

ConspectusKohn–Sham density functional theory (KS DFT) is arguably the most widely applied electronic-structure method with tens of thousands publications each year in a wide variety fields. Its importance and usefulness can thus hardly be overstated. The central quantity that determines accuracy KS DFT calculations exchange-correlation functional. exact form unknown, or better "unknowable", therefore derivation ever more accurate yet efficiently applicable approximate functionals "holy grail" field. In this context, simultaneous minimization so-called delocalization errors static correlation greatest challenge needs to overcome as we move toward computationally efficient methods. many cases, an improvement on one these two aspects (also often termed fractional-charge fractional-spin errors, respectively) generates deterioration other one. Here report recent notable progress escaping "zero-sum-game" by constructing new based exact-exchange energy density. particular, local hybrid range-separated are discussed incorporate additional terms deal well errors. Taking hints from coordinate-space models nondynamical strong electron correlations (the B13 KP16/B13 models), position-dependent functions cover real space have been devised incorporated into local-mixing determining position-dependence admixture hybrids treatment range separation hybrids. While initial followed closely frameworks, meanwhile simpler real-space ratios semilocal densities found, providing basis for relatively simple numerically convenient functionals. Notably, correction either increase decrease locally (and interelectronic-distance space), leading even regions negative cases particularly correlations. Efficient implementations fast computer code (Turbomole) using seminumerical integration techniques make such promising tools complicated composite systems research areas, where simultaneously small crucial. First real-world application examples provided, including stretched bonds, symmetry-breaking hyperfine coupling open-shell transition-metal complexes, reduction computation nuclear shieldings magnetizabilities. newest versions (e.g., ωLH23tdE) retain excellent frontier-orbital energies correct asymptotic potential underlying ωLH22t while improving substantially strong-correlation cases. further linked performance impactful deep-neural-network "black-box" DM21, which itself may viewed hybrid.

Language: Английский

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Data-Driven Improvement of Local Hybrid Functionals: Neural-Network-Based Local Mixing Functions and Power-Series Correlation Functionals

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 13, 2025

Local hybrid functionals (LHs) use a real-space position-dependent admixture of exact exchange (EXX), governed by local mixing function (LMF). The systematic construction LMFs has been hampered over the years lack physical constraints on their valence behavior. Here, we exploit data-driven approach and train new type "n-LMF" as relatively shallow neural network. input features are meta-GGA character, while W4-17 atomization-energy BH76 reaction-barrier test sets have used for training. Simply replacing widely "t-LMF" LH20t functional n-LMF provides LH24n-B95 functional. Augmented DFT-D4 dispersion corrections, LH24n-B95-D4 remarkably improves WTMAD-2 value large GMTKN55 suite general main-group thermochemistry, kinetics, noncovalent interactions (NCIs) from 4.55 to 3.49 kcal/mol. As found limited flexibility B95c correlation disfavor much further improvement NCIs, proceeded replace it an optimized B97c-type power-series expansion. This gives LH24n LH24n-D4 3.10 kcal/mol, so far lowest rung 4 in self-consistent calculations. perform moderately well organometallic transition-metal energetics leaving room improvements that area. Compared complete neural-network like DM21, present more tailored just LMF flexible but well-defined human-designed LH retains possibility graphical analyses gain deeper understanding. We find both recent x-LMF suppress so-called gauge problem hybrids without adding calibration required other LMFs. plots show this can be traced back values small-density region between interacting atoms NCIs n- x-LMFs low t-LMF. also trained covalent bonds deteriorating binding energies. current enables fast efficient routine calculations using n-LMFs Turbomole.

Language: Английский

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Suppressing the gauge problem in local hybrid functionals without a calibration function: The choice of local mixing function

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 161(16)

Published: Oct. 23, 2024

Modern functionals based on the exact-exchange (EXX) energy density like local hybrid (LHs) or range-separated LHs have recently received additional attention due to their advantages over established when it comes balance between self-interaction errors and static-correlation errors. A possible theoretical drawback of such years has been so-called gauge problem inherent ambiguity exchange-energy densities. LH20t more sophisticated thereon constructed using suitably optimized calibration functions (CFs) minimize mismatch semi-local EXX Here, we show that unphysical contributions arising from may also be reduced significantly without a CF by tailoring position-dependence admixture (local mixing function, LMF) in way suppress spurious positive energy-density locally space. This is achieved building x-LMFs upon ratio The resulting LH24x functional provides similar accuracy, e.g., for GMTKN55 test suite, as LH20t, but introduction CF! We provide detailed comparative analyses integrated energies spatially resolved good performances chemically relevant differences are some extent core nature artifacts cancel out efficiently.

Language: Английский

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Spin-Symmetry Breaking and Hyperfine Couplings in Transition-Metal Complexes Revisited Using Density Functionals Based on the Exact-Exchange Energy Density

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(5), P. 2033 - 2048

Published: Feb. 27, 2024

A small set of mononuclear manganese complexes evaluated previously for their Mn hyperfine couplings (HFCs) has been analyzed using density functionals based on the exact-exchange energy density─in particular, spin symmetry breaking (SSB) found when hybrid functionals. Employing various strong-correlation corrected local hybrids (scLHs) and range-separated (scRSLHs) with or without additional corrections to mixing functions (LMFs) mitigate delocalization errors (DE), SSB associated dipolar HFCs [Mn(CN)4]2–, MnO3, [Mn(CN)4N]−, [Mn(CN)5NO]2– (the latter cluster embedding) have examined. Both (sc)-correction DE-correction terms help diminish correct HFCs. The DE are more effective, effects sc depend damping factors. Interestingly, DE-corrections reduce valence-shell polarization (VSSP) thus by locally enhancing (EXX) admixture near metal center thereby diminishing spin-density onto ligand atoms. In contrast, EXX locally, mostly specific This then reduces VSSP as well. performance scLHs scRSLHs isotropic also analyzed, particular attention core–shell spin-polarization contributions. Further sc-corrected functionals, such KP16/B13 construction DM21 deep-neural-network functional,

Language: Английский

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A benchmark study of dioxygen complexes based on coupled cluster and density functional theory

Published: June 24, 2024

A set of five compounds containing peroxo, superoxo or bis-mu-oxo moieties has been studied in the gas phase using CCSD(T)/aug-cc-pVQZ, also combination with Goodson’s continued fraction approach. The corresponding analytical frequencies corroborate assignments bands from experiments, and thus provide a consistent reference data that can be used for benchmarking range density functional approximations. total 100 functionals have checked general bond lengths, specific peroxo/superoxo angles, vibrational electronic energies. There is not one performs equally well all these properties, even within class functionals.

Language: Английский

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Combining real-space and local range separation—The MH24 locally range-separated local hybrid functional

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 161(21)

Published: Dec. 3, 2024

In this work, the development of a new general-purpose exchange–correlation hybrid functional based on recent locally range-separated local approach is presented. particular, functional, denoted as MH24, combines non-empirical treatment admixture long-range exact exchange with real-space separation for exact-exchange governed by mixing function (LMF) and empirical LYP-based correlation to enable flexible description same- opposite-spin effects. The nine parameters MH24 model have been optimized using state-of-the-art super-self-consistent-field approach, which exploits sensitivity specific properties, such core ionization potentials, electron affinities, atomization energies, in regions real space LMF into core, valence, asymptotic part. functionals are shown be able simultaneously provide good accuracy valence properties well affinities noble gas dimer dissociation curves, while satisfying multiple known constraints related functionals. thus major step toward more sophisticated models.

Language: Английский

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Chemically Accurate Singlet-Triplet Gaps of Arylcarbenes from Local Hybrid Density Functionals

Published: May 3, 2024

Singlet-triplet (ST) gaps are key descriptors of carbenes, because their properties and reactivity strongly spin-dependent. However, the theoretical prediction ST is challenging generally thought to require elaborate correlated wavefunction methods or double-hybrid density functionals. By evaluating two recent test sets arylcarbenes (AC12 AC18), we show that local hybrid functionals based on "common t" mixing function (LMF) model achieve mean absolute errors below 1 kcal/mol at a computational cost only slightly higher than global An analysis correlation contributions suggests accuracy common t-LMF mainly due an improved description nondynamical which, unlike exchange, not additive in each spin-channel. Although spin-nonadditivity can be achieved using spin polarization alone, "common", i.e., spin-unresolved, iso-orbital indicator t for constructing LMF found critical consistent arylcarbenes. The results support view LHs as vehicles improve rather sophisticated exchange approaches.

Language: Английский

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Chemically Accurate Singlet–Triplet Gaps of Arylcarbenes from Local Hybrid Density Functionals

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: unknown

Published: July 16, 2024

Singlet–triplet (ST) gaps are key descriptors of carbenes, because their properties and reactivity strongly spin-dependent. However, the theoretical prediction ST is challenging generally thought to require elaborate correlated wave function methods or double-hybrid density functionals. By evaluating two recent test sets arylcarbenes (AC12 AC18), we show that local hybrid functionals based on "common t" mixing (LMF) model achieve mean absolute errors below 1 kcal/mol at a computational cost only slightly higher than global An analysis correlation contributions suggests accuracy common t-LMF mainly due an improved description nondynamical which, unlike exchange, not additive in each spin-channel. Although spin-nonadditivity can be achieved using spin polarization alone, "common", i.e., spin-unresolved, iso-orbital indicator t for constructing LMF found critical consistent arylcarbenes. The results support view LHs as vehicles improve rather sophisticated exchange approaches.

Language: Английский

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A benchmark study of dioxygen complexes based on coupled cluster and density functional theory

SciPost Chemistry, Journal Year: 2024, Volume and Issue: 3(1)

Published: Aug. 13, 2024

A set of five compounds containing peroxo, superoxo or bis-μ-oxo moieties has been studied in the gas phase using CCSD(T)/aug-cc-pVQZ, also combination with Goodson’s continued fraction approach. The corresponding analytical frequencies corroborate assignments bands from experiments, and thus provide a consistent reference data that can be used for benchmarking range density functional approximations. total 100 functionals have checked general bond lengths, specific peroxo/superoxo angles, vibrational frequencies. There is not one performs equally well all these properties, even within class functionals.

Language: Английский

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Post‐CCSD(T) Thermochemistry of Chlorine Fluorides as a Challenging Test Case for Evaluating Density Functional Theory and Composite Ab Initio Methods

ChemPhysChem, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 27, 2024

Quantum chemistry plays a key role in exploring the chemical properties of highly reactive chlorine polyfluoride compounds (ClF

Language: Английский

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