Δ-based composite models for calculating x-ray absorption and emission energies

Zamani, Abdulrahman Y.; Hratchian, Hrant P.

doi:10.1063/5.0178052

The Journal of Chemical Physics

2023

DOI: 10.1063/5.0178052

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Δ-based composite models for calculating x-ray absorption and emission energies

Abdulrahman Y. Zamani,

Hrant P. Hratchian

Abstract: A practical ab initio composite method for modeling x-ray absorption and non-resonant x-ray emission is presented. Vertical K-edge excitation and emission energies are obtained from core-electron binding energies calculated with spin-projected ΔHF/ΔMP and outer-core ionization potentials/electron affinities calculated with electron propagator theory. An assessment of the combined methodologies against experiment is performed for a set of small molecules containing second-row elements.

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2024

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Cited by 3 publications

References 115 publications

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Long-range Corrected Density Functional Theory Including a Two-Gaussian Hartree−Fock Operator for High Accuracy Core-excitation Energy Calculations of Both the Second- and Third-Row Atoms (LC2gau-core-BOP)

Ahn,

Nakajima,

Hirao

et al. 2024

J. Chem. Theory Comput.

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In the previous work, LCgau-core-BOP, which includes the short-range interelectronic Gaussian attenuating Hartree−Fock (HF) exchange to the long-range HF exchange, showed high accuracy core-excitation energies from 1s orbitals of the second-row atoms (1s → π*, 1s → σ*, 1s → n*, and 1s → Rydberg), but underestimates the core-excitation energies from 1s orbitals of the third-row atoms. To improve this, we added one more Gaussian attenuating HF exchange to LCgau-core-BOP. We named it LC2gau-core-BOP, which achieves a mean absolute error (MAE) of 0.6 and 0.3 eV for core excitation energies of the second-and third-row atoms of the tested small molecules, respectively. We found that the inclusion of the short-range interelectronic HF exchange at a distance ranging from 0.2 to 0.6 a.u. contributes to the increase of performances on 1s orbital energy calculations of the second-row atoms, while the inclusion of more short-range interelectronic HF exchange at a distance ranging from 0 to 0.2 a.u. does to the increase of performance on 1s orbital energy calculations of the third-row atoms. It is notable that all of these improvements were accomplished using flexible Gaussian attenuating HF exchange inclusion. LC2gau-core-BOP shows deviations of less than 0.8 eV from experimental values for all of the core-excitation energies of the tested medium-size molecules consisting of thymine, oxazole, glycine, and dibenzothiophene sulfone. Moreover, by optimizing one parameter of the OP correlation functional, LC2gau-core-BOP provides atomization energies over the G3 test set with an accuracy comparable to that of B3LYP.

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Long-range Corrected Density Functional Theory Including a Two-Gaussian Hartree−Fock Operator for High Accuracy Core-excitation Energy Calculations of Both the Second- and Third-Row Atoms (LC2gau-core-BOP)

Ahn,

Nakajima,

Hirao

et al. 2024

J. Chem. Theory Comput.

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Accelerated Computer-Aided Screening of Optical Materials: Investigating the Potential of Δ-SCF Methods to Predict Emission Maxima of Large Dye Molecules

Tripathy,

Flood,

Raghavachari

2024

J. Phys. Chem. A

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Accurate simulation of electronic excited states of large chromophores is often difficult due to the computationally expensive nature of existing methods. Common approximations such as fragmentation methods that are routinely applied to ground-state calculations of large molecules are not easily applicable to excited states due to the delocalized nature of electronic excitations in most practical chromophores. Thus, special techniques specific to excited states are needed. Δ-SCF methods are one such approximation that treats excited states in a manner analogous to that for ground-state calculations, accelerating the simulation of excited states. In this work, we employed the popular initial maximum overlap method (IMOM) to avoid the variational collapse of the electronic excited state orbitals to the ground state. We demonstrate that it is possible to obtain emission energies from the first singlet (S 1 ) excited state of many thousands of dye molecules without any external intervention. Spin correction was found to be necessary to obtain accurate excitation and emission energies. Using thousands of dye-like chromophores and various solvents (12,318 combinations), we show that the spin-corrected initial maximum overlap method accurately predicts emission maxima with a mean absolute error of only 0.27 eV. We further improved the predictive accuracy using linear fit-based corrections from individual dye classes to achieve an impressive performance of 0.17 eV. Additionally, we demonstrate that IMOM spin density can be used to identify the dye class of chromophores, enabling improved prediction accuracy for complex dye molecules, such as dyads (chromophores containing moieties from two different dye classes). Finally, the convergence behavior of IMOM excited state SCF calculations is analyzed briefly to identify the chemical space, where IMOM is more likely to fail.

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Elucidating Anomalous Intensity Ratios in Chlorine L-Edge X-ray Absorption Spectroscopy: Multiplet Effects and Core Rydberg Transitions

Lin,

Liu,

Zhang

et al. 2024

J. Phys. Chem. A

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A relativistic core−valence-separated equation-of-motion coupled cluster (CVS-EOM-CC) study of chlorine L 2,3 -edge X-ray absorption near-edge structure (XANES) spectra using CH 3 Cl and CH 2 ICl as representative molecules is reported. The nearly identical intensity for the main features in the L 2 -and L 3 -edge XANES spectra is attributed to multiplet effects and the overlap between core−valence and core Rydberg transitions. The multiplet effects originating from the interaction between the core hole and the C−Cl σ* orbitals account for around half of the deviation of the L 3 and L 2 intensity ratio from the 2:1 ratio of the numbers of 2p 3/2 and 2p 1/2 electrons. The 2p 3/2 → 4s core Rydberg transitions are shown to overlap with the 2p 1/2 → σ* transitions and contribute to the other half of the intensity anomaly. We demonstrate that triple excitations in CVS-EOM-CC calculations play important roles in accurate simulation of the overlap between the 2p 1/2 → σ* and 2p 3/2 → 4s transitions.

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Δ-based composite models for calculating x-ray absorption and emission energies

Cited by 3 publications

References 115 publications

Long-range Corrected Density Functional Theory Including a Two-Gaussian Hartree−Fock Operator for High Accuracy Core-excitation Energy Calculations of Both the Second- and Third-Row Atoms (LC2gau-core-BOP)

Long-range Corrected Density Functional Theory Including a Two-Gaussian Hartree−Fock Operator for High Accuracy Core-excitation Energy Calculations of Both the Second- and Third-Row Atoms (LC2gau-core-BOP)

Accelerated Computer-Aided Screening of Optical Materials: Investigating the Potential of Δ-SCF Methods to Predict Emission Maxima of Large Dye Molecules

Elucidating Anomalous Intensity Ratios in Chlorine L-Edge X-ray Absorption Spectroscopy: Multiplet Effects and Core Rydberg Transitions

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