A new parameterization of the DFT/CIS method with applications to core-level spectroscopy

The Journal of Chemical Physics, Journal Year: 2024, Volume and Issue: 161(4)

Published: July 25, 2024

Time-dependent density functional theory (TD-DFT) within a restricted excitation space is an efficient means to compute core-level energies using only small subset of the occupied orbitals. However, core-to-valence are significantly underestimated when standard exchange-correlation functionals used, which partly traceable systemic issues with TD-DFT's description Rydberg and charge-transfer excited states. To mitigate this, we have implemented empirically modified combination configuration interaction single substitutions (CIS) based on Kohn-Sham orbitals, known as "DFT/CIS." This semi-empirical approach well-suited for simulating x-ray near-edge spectra, it contains sufficient exact exchange model excitations yet retains DFT's low-cost dynamical electron correlation. Empirical corrections matrix elements enable semi-quantitative simulation spectra without need significant posteriori shifts; this should be useful in complex molecules materials multiple overlapping edges. Parameter optimization use specific range-separated hybrid makes black-box method intended both core valence spectroscopy. Results herein demonstrate that realistic K-edge absorption emission can obtained second- third-row 3d transition metals, promising results L-edge well. DFT/CIS calculations require absolute shifts considerably smaller than what typical TD-DFT.

Language: Английский

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Correction: Visualizing and characterizing excited states from time-dependent density functional theory

Physical Chemistry Chemical Physics, Journal Year: 2024, Volume and Issue: 26(35), P. 23503 - 23504

Published: Jan. 1, 2024

Correction for 'Visualizing and characterizing excited states from time-dependent density functional theory' by John M. Herbert

Language: Английский

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Reformulation of Time-Dependent Density Functional Theory for Nonperturbative Dynamics: The Rabi Oscillation Problem Resolved

Physical Review Letters, Journal Year: 2024, Volume and Issue: 133(9)

Published: Aug. 27, 2024

Rabi oscillations have long been thought to be out of reach in simulations using time-dependent density functional theory (TDDFT), a prominent symptom the failure adiabatic approximation for nonperturbative dynamics. We present reformulation TDDFT which requires response quantities only, thus enabling an predict such dynamics accurately because is evaluated on close ground state, instead fully density. Our applies any real-time dynamics, redeeming far from equilibrium. Examples resonantly-driven local excitation model He atom, and charge-transfer LiCN molecule are given.Received 22 April 2024Accepted 18 July 2024DOI:https://doi.org/10.1103/PhysRevLett.133.096401© 2024 American Physical SocietyPhysics Subject Headings (PhySH)TechniquesDensity theoryDensity developmentTime-dependent DFTAtomic, Molecular & Optical

Language: Английский

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The Analysis of Electron Densities: From Basics to Emergent Applications

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(22), P. 12661 - 12737

Published: Nov. 15, 2024

The electron density determines all properties of a system nuclei and electrons. It is both computable observable. Its topology allows gaining insight into the mechanisms bonding other phenomena in way that complementary to beyond available from molecular orbital picture formal oxidation state (FOS) formalism. ability derive mechanistic also important with methods where orbitals are not available, such as orbital-free functional theory (OF-DFT). While topology-based analyses QTAIM (quantum atoms-in-molecules) have been widely used, novel, vector-based techniques recently emerged next-generation (NG) QTAIM. Density-dependent quantities actively used machine learning (ML)-based methods, particular, for ML DFT development, including machine-learnt kinetic energy functionals. We review its recent extensions NG-QTAIM localization-delocalization matrices (LDM) their uses analysis bonding, conformations, redox reactions excitations, well ultrafast phenomena. research showing direct can circumvent certain pitfalls FOS formalism, particular description anionic redox, (spherically) projected states analysis. discuss density-based construction functionals prospects applications get OF-DFT developed time-dependent OF-DFT.

Language: Английский

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Importance of Orbital Invariance in Quantifying Electron-Hole Separation and Exciton Size

Published: Aug. 19, 2024

A fundamental tenet of quantum mechanics is that properties should be independent representation. In self-consistent field methods such as density functional theory, this manifests a requirement invariant with respect to unitary transformations the occupied molecular orbitals and (separately) unoccupied orbitals. Various ad hoc measures excited-state charge separation are commonly used analyze time-dependent density-functional calculations violate requirement, they based on incoherent averages excitation amplitudes rather than over coherent superposition states. As result, these metrics afford markedly different values in various common representations including canonical orbitals, Boys-localized natural transition (NTOs). Numerical charge-transfer can unstable basis-set expansion may nonsensical presence extremely diffuse basis functions. contrast, well-defined expectation stable, representation-invariant, physically interpretable. Although NTO representation improves stability diagnostics, it remains case an average only connected value absence superposition. For satisfy condition, particle hole matrices must each dominated by single eigenvector so well described pair NTOs. Counterexamples readily found where not case.

Language: Английский

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A new parameterization of the DFT/CIS method with applications to core-level spectroscopy

Published: May 27, 2024

Time-dependent density functional theory (TD-DFT) within a restricted excitation space is an efficient means to compute core-level energies, using only small subset of the occupied orbitals. However, core-to-valence energies are significantly underestimated when standard exchange-correlation functionals used, which partly traceable systemic issues with TD-DFT's description Rydberg and charge-transfer excited states. To mitigate this, we have implemented empirically modified combination configuration interaction single substitutions (CIS) based on Kohn-Sham orbitals, known as "DFT/CIS". This semi-empirical approach well-suited for simulating x-ray near-edge spectra, it contains sufficient exact exchange model excitations yet retains DFT's low-cost dynamical electron correlation. Empirical corrections matrix elements enable semi-quantitative simulation spectra without need significant posteriori shifts; this should be useful in complex molecules materials multiple overlapping edges. Parameter optimization use specific range-separated hybrid makes black-box method intended both core valence spectroscopy. Results herein demonstrate that realistic K-edge absorption emission can obtained second- third-row 3d transition metals, promising results L-edge well. DFT/CIS calculations require absolute shifts considerably smaller than what typical TD-DFT.

Language: Английский

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Whispering gallery mode sensing through the lens of quantum optics, artificial intelligence, and nanoscale catalysis

Applied Physics Letters, Journal Year: 2024, Volume and Issue: 125(3)

Published: July 15, 2024

Ultra-sensitive sensors based on the resonant properties of whispering gallery modes (WGMs) can detect fractional changes in nanoscale environments down to length and time scales single molecules. However, it is challenging isolate single-molecule signals from competing noise sources experiments, such as thermal mechanical noise, and—at most fundamental level—the shot limit classical light. Additionally, contrast traditional bulk refractive index measurements, analyzing complicated by localized nature their interactions with field gradients. This perspective discusses multifaceted solutions these challenges, including use quantum light boost signal-to-noise ratio experiments leveraging power supercomputers predict electronic response molecules WGM optoplasmonic fields. We further discuss role machine learning sensing, several advanced models that molecular polarizability solvent effects. These advancements spectroscopy computational modeling help decipher mechanics enzymes, enable studies catalysis nanoscale, probe

Language: Английский

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Assessing and applying DFT approaches for geometries and UV–Vis absorption spectra of tetragonal iron(II) complexes

Theoretical Chemistry Accounts, Journal Year: 2024, Volume and Issue: 143(11)

Published: Oct. 12, 2024

Language: Английский

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