Extension of the D3 and D4 London Dispersion Corrections to the full Actinides Series

Physical Chemistry Chemical Physics, Год журнала: 2024, Номер 26(32), С. 21379 - 21394

Опубликована: Янв. 1, 2024

Efficient dispersion corrections are an indispensable component of modern density functional theory, semi-empirical quantum mechanical, and even force field methods. In this work, we extend the well established D3 D4 London to full actinides series, francium, radium. To keep consistency with existing versions, original parameterization strategy model was only slightly modified. This includes improved reference Hirshfeld atomic partial charges at ωB97M-V/ma-def-TZVP level fit required electronegativity equilibration charge (EEQ) model. context, developed a new actinide data set called AcQM, which covers most common molecular compound space. Furthermore, efficient calculation dynamic polarizabilities that needed construct

Язык: Английский

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Capturing Strong Correlation in Molecules with Phaseless Auxiliary-Field Quantum Monte Carlo Using Generalized Hartree–Fock Trial Wave Functions

Journal of Chemical Theory and Computation, Год журнала: 2025, Номер unknown

Опубликована: Янв. 16, 2025

Generalized Hartree–Fock (GHF) is a long-established electronic structure method that can lower the energy (compared to spin-restricted variants) by breaking physical wave function symmetries, namely S^2 and S^z. After an exposition of GHF theory, we assess use trial functions in phaseless auxiliary field quantum Monte Carlo (ph-AFQMC-G) calculations strongly correlated molecular systems including symmetrically stretched hydrogen rings, carbon dioxide, dioxygen. Imaginary time propagation able restore symmetry yields energies comparable or better accuracy than CCSD(T) with unrestricted HF references, consistently smooth dissociation curves─a remarkable result given relative scalability ph-AFQMC-G larger system sizes. The present exploration model marks promising starting point for future studies more chemically relevant molecules, demonstrates provides highly accurate (and, contrast active-space-based trials, relatively black box always size-consistent) description challenging exhibiting, e.g., antiferromagnetic coupling and/or geometric spin frustration.

Язык: Английский

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Do Optimally Tuned Range-Separated Hybrid Functionals Require a Reparametrization of the Dispersion Correction? It Depends

Journal of Chemical Theory and Computation, Год журнала: 2023, Номер 19(22), С. 8097 - 8107

Опубликована: Ноя. 13, 2023

For ground- and excited-state studies of large molecules, it is the state art to combine (time-dependent) DFT with dispersion-corrected range-separated hybrid functionals (RSHs), which ensures an asymptotically correct description exchange effects London dispersion. Specifically for studying excited states, common practice tune range-separation parameter ω (optimal tuning), can further improve accuracy. However, since optimal tuning essentially changes functional, unclear if how much parameters used dispersion correction depend on chosen value. To answer this question, we explore interdependency by refitting DFT-D4 model six established RSHs over a wide range values (0.05-0.45 a0-1) using set noncovalently bound molecular complexes. The results reveal some surprising differences among investigated functionals: While PBE-based ωB97M-D4 generally exhibit weak robust performance values, B88-based RSHs, specifically LC-BLYP, are strongly affected. these, even minor reduction from default value manifests in strong systematic overbinding poor typical optimally tuned values. Finally, discuss strategies mitigate these issues reflect context employed D4 optimization algorithm fit set, outlining future improvements.

Язык: Английский

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ΔDFT Predicts Inverted Singlet–Triplet Gaps with Chemical Accuracy at a Fraction of the Cost of Wave Function-Based Approaches

The Journal of Physical Chemistry Letters, Год журнала: 2024, Номер 15(31), С. 8065 - 8077

Опубликована: Июль 31, 2024

Efficient OLEDs need to quickly convert singlet and triplet excitons into photons. Molecules with an inverted singlet–triplet energy gap (INVEST) are promising candidates for this task. However, typical INVEST molecules have drawbacks like too low oscillator strengths excitation energies. High-throughput screening could identify suitable molecules, but existing methods problematic: The workhorse method TD-DFT cannot reproduce inversion, while wave function-based slow. This study proposes a state-specific based on unrestricted Kohn–Sham DFT common hybrid functionals. Tuned the new INVEST15 benchmark set, achieves error of less than 1 kcal/mol, which is traced back cancellation between spin contamination dynamic correlation. Applied larger structurally diverse NAH159 set in black-box fashion, maintains small (1.2 kcal/mol) accurately predicts signs 83% cases, confirming its robustness suitability workflows.

Язык: Английский

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Beyond CCSD(T) Accuracy at Lower Scaling with Auxiliary Field Quantum Monte Carlo

Journal of Chemical Theory and Computation, Год журнала: 2025, Номер unknown

Опубликована: Фев. 5, 2025

We introduce a black-box auxiliary field quantum Monte Carlo (AFQMC) approach to perform highly accurate electronic structure calculations using configuration interaction singles and doubles (CISD) trial states. This method consistently provides more energy estimates than coupled cluster with perturbative triples (CCSD(T)), often regarded as the gold standard in chemistry. level of precision is achieved at lower asymptotic computational cost, scaling O(N6) compared O(N7) CCSD(T). provide numerical evidence supporting these findings through results for challenging main group transition metal-containing molecules.

Язык: Английский

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Scalable Ab Initio Electronic Structure Methods with Near Chemical Accuracy for Main Group Chemistry

The Journal of Physical Chemistry A, Год журнала: 2024, Номер 128(28), С. 5796 - 5807

Опубликована: Июль 6, 2024

This study evaluates the precision of widely recognized quantum chemical methodologies, CCSD(T), DLPNO-CCSD(T), and localized ph-AFQMC, for determining thermochemistry main group elements. DLPNO-CCSD(T) which offer greater scalability compared to canonical have emerged over past decade as pivotal in producing precise benchmark data. Our investigation includes closed-shell, neutral molecules, focusing on their heat formation atomization energy sourced from four specific small molecule data sets. First, we selected molecules G2 G3 sets, noted reliable experimental Additionally, incorporate W4-11 W4-17 provide high-level theoretical reference values at 0 K. findings reveal that both ph-AFQMC methods are capable achieving a root-mean-square deviation less than 1 kcal/mol across combined set, aligning with threshold accuracy. Moreover, make efforts confine maximum deviations within 2 kcal/mol, degree significantly broadens applicability these fields such biology materials science.

Язык: Английский

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Improved CPS and CBS Extrapolation of PNO-CCSD(T) Energies: The MOBH35 and ISOL24 Data Sets

Journal of Chemical Theory and Computation, Год журнала: 2024, Номер 20(7), С. 2740 - 2750

Опубликована: Март 21, 2024

Computation of heats reaction large molecules is now feasible using the domain-based pair natural orbital (PNO)-coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] theory. However, to obtain agreement within 1 kcal/mol experiment, it necessary eliminate basis set incompleteness error, which comprises both AO error PNO truncation error. Our investigation into convergence canonical limit PNO-CCSD(T) energies with threshold T shows that errors follow model E(T)=E+AT1/2. Therefore, can be eliminated a simple two-point CPS extrapolation so subsequent CBS not limited by residual Using ISOL24 MOBH35 data sets, we find are larger for significant static correlation use very tight thresholds T=10−8 ensure do exceed kcal/mol. We present lower-cost scheme uses information from small sets estimate sets. In this way, CCSD(T) calculations on sizable reliably estimated in practical way. approach, report near complete (CBS)-CCSD(T) full

Язык: Английский

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The p-block challenge: assessing quantum chemistry methods for inorganic heterocycle dimerizations

Physical Chemistry Chemical Physics, Год журнала: 2024, Номер 26(18), С. 13884 - 13908

Опубликована: Янв. 1, 2024

We present a benchmark set of dimerization energies “inorganic benzenes” composed all non-carbon p-block elements main groups III to VI up polonium representing challenge contemporary quantum chemical methods.

Язык: Английский

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Femtosecond Core-Level Spectroscopy Reveals Involvement of Triplet States in the Gas-Phase Photodissociation of Fe(CO)₅

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(32), С. 22711 - 22723

Опубликована: Авг. 2, 2024

Excitation of iron pentacarbonyl [Fe(CO)

Язык: Английский

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On the notion of strong correlation in electronic structure theory

Faraday Discussions, Год журнала: 2024, Номер 254, С. 53 - 75

Опубликована: Янв. 1, 2024

Strong correlation has been said to have many faces, and appears synonyms of questionable suitability. In this work we aim not define the term once for all, but highlight one possibility that is both rigorously defined physically transparent, remains so in reference molecules quantum lattice models. We survey molecular examples - hydrogen systems (H

Язык: Английский

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