QUEST#4X: An Extension of QUEST#4 for Benchmarking Multireference Wave Function Methods

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

Published: Jan. 28, 2025

Given a number of data sets for evaluating the performance single reference methods low-lying excited states closed-shell molecules, comprehensive set assessing multireference open-shell systems is still lacking. For this reason, we propose an extension (QUEST#4X) radical subset QUEST#4 (J. Chem. Theory Comput. 2020, 16, 3720) to cover 110 doublet and 39 quartet states. Near-exact results obtained by iterative configuration interaction with selection second-order perturbation correction (iCIPT2) are taken as benchmark calibrate static-dynamic-static (SDSCI) theory (SDSPT2), which minimal MRCI CI-like theory, respectively. It found that SDSCI very close in accuracy internally contracted singles doubles (ic-MRCISD), although its computational cost just one iteration latter. Unlike most variants MRPT2, SDSPT2 treats multiple same way performs similarly multistate n-electron valence (MS-NEVPT2). These findings put on firm basis.

Language: Английский

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Accurate computation of quantum excited states with neural networks

Science, Journal Year: 2024, Volume and Issue: 385(6711)

Published: Aug. 22, 2024

We present an algorithm to estimate the excited states of a quantum system by variational Monte Carlo, which has no free parameters and requires orthogonalization states, instead transforming problem into that finding ground state expanded system. Arbitrary observables can be calculated, including off-diagonal expectations, such as transition dipole moment. The method works particularly well with neural network ansätze, combining this FermiNet Psiformer we accurately recover excitation energies oscillator strengths on range molecules. achieve accurate vertical benzene-scale molecules, challenging double excitations. Beyond examples presented in work, expect technique will interest for atomic, nuclear, condensed matter physics.

Language: Английский

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Capturing the Elusive Curve-Crossing in Low-Lying States of Butadiene with Dressed TDDFT

The Journal of Physical Chemistry Letters, Journal Year: 2025, Volume and Issue: unknown, P. 703 - 709

Published: Jan. 10, 2025

A striking example of the need to accurately capture states double-excitation character in molecules is seen predicting photoinduced dynamics small polyenes. Due coupling electronic and nuclear motions, dark 21Ag state, known have character, can be reached after an initial photoexcitation bright 11Bu state via crossings their potential energy surfaces. However, shapes surfaces are so poorly captured by most structure methods, that crossing missed or substantially mis-located. We demonstrate frequency-dependent kernel dressed TDDFT beyond Tamm-Dancoff successfully captures curve-crossing, providing surface close highly accurate but more expensive δ-CR-EOMCC(2,3) benchmark reference. This, along with its prediction excitation makes a practical route quantities needed modeling ultrafast molecules.

Language: Английский

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Finite-Size Effects in Periodic EOM-CCSD for Ionization Energies and Electron Affinities: Convergence Rate and Extrapolation to the Thermodynamic Limit

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

Published: Feb. 4, 2025

We investigate the convergence of quasiparticle energies for periodic systems to thermodynamic limit using increasingly large simulation cells corresponding dense integration meshes in reciprocal space. The are computed at level equation-of-motion coupled-cluster theory ionization (IP-EOM-CC) and electron attachment processes (EA-EOM-CC). By introducing an electronic correlation structure factor, expected asymptotic rates with different dimensionality formally derived. rigorously test these derivations through numerical simulations trans-polyacetylene IP/EA-EOM-CCSD G0W0@HF approximation, which confirm predicted behavior. Our findings provide a solid foundation efficient schemes correct finite-size errors calculations.

Language: Английский

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Reference CC3 Excitation Energies for Organic Chromophores: Benchmarking TD-DFT, BSE/GW, and Wave Function Methods

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 5, 2024

To expand the QUEST database of highly accurate vertical transition energies, we consider a series large organic chromogens ubiquitous in dye chemistry, such as anthraquinone, azobenzene, BODIPY, and naphthalimide. We compute, at CC3 level theory, singlet triplet energies associated with low-lying excited states. This leads to collection more than 120 new excitation energies. For several transitions, have been able determine CCSDT compact basis set, finding minimal deviations from values for most Subsequently, employ these reference benchmark lower-order wave function approaches, including popular ADC(2) CC2 schemes, well time-dependent density-functional theory (TD-DFT), both without applying Tamm-Dancoff approximation (TDA). At TD-DFT level, evaluate panel global, range-separated, local, double hybrid functionals. Additionally, assess performance Bethe-Salpeter equation (BSE) formalism relying on G0W0 evGW quasiparticle evaluated various starting points. It turns out that ADC(2.5) are models among those respective O(N5) O(N6) scalings system size. In contrast, CCSD does not outperform CC2. The best performing exchange-correlation functionals include BMK, M06-2X, M06-SX, CAM-B3LYP, ωB97X-D, LH20t, average approximately 0.20 eV or slightly below. Errors can be further reduced by considering hybrids. Both SOS-ωB88PP86 SOS-ωPBEPP86 exhibit particularly attractive performances overall quality par CC2, whereas PBE0-DH PBE-QIDH only less efficient. BSE/evGW calculations based Kohn-Sham points found effective but much their counterparts.

Language: Английский

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Theoretical Study of Spectroscopy and Photodynamics of Decatetraene as a Representative Dimethylated Polyene

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 27, 2025

The photodynamics and UV spectroscopy of decatetraene following excitation to the bright 1Bu state are studied theoretically, based on ab initio computations underlying potential energy (PE) surfaces. Both photophysical photochemical aspects investigated. former involves smaller amplitude displacements, – in addition determining multidimensional PE surfaces also a quantal treatment ensuing nuclear dynamics. inclusion 1Bu–2Ag vibronic interaction allows compute vibrational structure 1Ag–1Bu spectral band femtosecond internal conversion (population transfer). results compared with analogous features octatetraene octatriene. involving larger-amplitude displacements investigated from quantum-chemical point view, focusing stationary points seams conical intersections that involved. A comparison reveals contrasting their 2Ag minima, where latter is more stable dimethylated system. small barrier connecting these two states lies between 0.06 0.11 eV. nonradiative decay channels originating minima characterized by comparatively higher barriers influence outcome radiative processes different manner octatetraene.

Language: Английский

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Accurate and efficient prediction of double excitation energies using the particle–particle random phase approximation

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(9)

Published: March 3, 2025

Double excitations are crucial to understanding numerous chemical, physical, and biological processes, but accurately predicting them remains a challenge. In this work, we explore the particle–particle random phase approximation (ppRPA) as an efficient accurate approach for computing double excitation energies. We benchmark ppRPA using various exchange-correlation functionals 21 molecular systems two point defect systems. Our results show that with containing appropriate amounts of exact exchange provides accuracy comparable high-level wave function methods such CCSDT CASPT2, significantly reduced computational cost. Furthermore, demonstrate use starting from excited (N − 2)-electron state calculated by ΔSCF first time, well its application in bulk periodic These findings suggest is promising tool calculation partial energies both

Language: Английский

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Exploring the accuracy of the equation-of-motion coupled-cluster band gap of solids

Physical review. B./Physical review. B, Journal Year: 2025, Volume and Issue: 111(12)

Published: March 26, 2025

While the periodic equation-of-motion coupled-cluster (EOM-CC) method promises systematic improvement of electronic band gap calculations in solids, its practical application at singles and doubles level (EOM-CCSD) is hindered by severe finite-size errors feasible simulation cells. We present a hybrid approach combining EOM-CCSD with computationally less demanding GW approximation to estimate thermodynamic limit gaps for several insulators semiconductors. Our substantially reduces required cell sizes while maintaining accuracy. Comparisons experimental self-consistent GW reveal that deviations predictions correlate reduced single excitation character excited many-electron states. work not only provides tractable EOM-CC solids but also reveals fundamental insights into role excitations electronic-structure theory. Published American Physical Society 2025

Language: Английский

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Low-lying excited states of linear all-trans polyenes: the σ–π electron correlation and the description of ionic states

Physical Chemistry Chemical Physics, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Accurately describing ionic states requires addressing basis-set effects, size-extensivity errors, and, most importantly, σ–π electron correlation.

Language: Английский

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Two-Photon Absorption Strengths of Small Molecules: Reference CC3 Values and Benchmarks

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(20), P. 9093 - 9106

Published: Oct. 7, 2024

We present a large dataset of highly accurate two-photon transition strengths (δTPA) determined for standard small molecules. Our reference values have been calculated using the quadratic response implementation third-order coupled cluster method including iterative triples (Q-CC3). The aug-cc-pVTZ atomic basis set is used molecules with up to five non-hydrogen atoms, while larger are assessed aug-cc-pVDZ; differences due sets discussed. This dataset, encompassing 82 singlet transitions various characters (Rydberg, valence, and double excitations), enables comprehensive benchmark smaller alternative wavefunction methods when Q-CC3 calculations become beyond reach as well time-dependent density functional theory (TD-DFT) approaches. evaluated include equation-of-motion CCSD approximations, Q-CC2, second-order algebraic diagrammatic construction in its intermediate state representation (I-ADC2). In TD-DFT framework, commonly exchange–correlation functionals evaluted. extensive analysis provides quantitative assessment these methods, revealing how different system sizes, intensities, types affect their performances.

Language: Английский

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