On the basis set selection for calculations of core-level states: different strategies to balance cost and accuracy

Sarangi, Ronit; Vidal, Marta L.; Coriani, Sonia; Krylov, Anna I.

doi:10.1080/00268976.2020.1769872

Cited by 56 publications

(69 citation statements)

References 73 publications

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“…The 6-311G(2+,+)G** basis set with uncontracted core was used in all calculations. 80 The orbital character of the XAS transitions was analyzed using NTOs computed with the libwfa module 81 and Dyson orbitals. 14,15,82 They were visualized using MOLDEN.…”

Section: Theoretical Methods and Computational Detailsmentioning

confidence: 99%

Interplay of Open-Shell Spin-Coupling and Jahn–Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

et al. 2020

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Section: Theoretical Methods and Computational Detailsmentioning

confidence: 99%

Interplay of Open-Shell Spin-Coupling and Jahn–Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

et al. 2020

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“…TP core-hole calculations are regularly performed in codes that use all-electron atomic orbital basis sets [30] or codes that use plane waves and pseudopotentials [31]. In the former case, the binding energy from ΔSCF can yield highly accurate absolute energies if well-designed basis sets with sufficiently flexible core-functions are used [27,32,60,86]. In the case of pseudopotential plane-wave codes, in order to calculate dipole matrix elements, the full all-electron wave function needs to be reconstructed using the projectoraugmented-wave method [31,70].…”

Section: Ab Initio Simulation Of Nexafsmentioning

confidence: 99%

The nuts and bolts of core-hole constrained ab initio simulation for K-shell x-ray photoemission and absorption spectra

Klein

Hall

Maurer

2021

J. Phys.: Condens. Matter

122

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X-ray photoemission (XPS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy play an important role in investigating the structure and electronic structure of materials and surfaces. Ab initio simulations provide crucial support for the interpretation of complex spectra containing overlapping signatures. Approximate core-hole simulation methods based on density functional theory (DFT) such as the delta-self-consistent-field (ΔSCF) method or the transition potential (TP) method are widely used to predict K-shell XPS and NEXAFS signatures of organic molecules, inorganic materials and metal-organic interfaces at reliable accuracy and affordable computational cost. We present the numerical and technical details of our variants of the ΔSCF and TP method (coined ΔIP-TP) to simulate XPS and NEXAFS transitions. Using exemplary molecules in gas-phase, in bulk crystals, and at metal-organic interfaces, we systematically assess how practical simulation choices affect the stability and accuracy of simulations. These include the choice of exchange-correlation functional, basis set, the method of core-hole localization, and the use of periodic boundary conditions (PBC). We particularly focus on the choice of aperiodic or periodic description of systems and how spurious charge effects in periodic calculations affect the simulation outcomes. For the benefit of practitioners in the field, we discuss sensible default choices, limitations of the methods, and future prospects.

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“…The 6-311G(2+,+)G** basis set with uncontracted core was used in all calculations. 70 The orbital character of the XAS transitions was analyzed using natural transition orbitals (NTOs) computed with the libwfa module 71 and Dyson orbitals; 15,16,72 they were visualized using MOLDEN. 73 All calculations were carried out using the Q-Chem electronic structure package, 74,75 except for some test EOM-CCSDT calculations, which were carried out using a modified version of the MRCC 76 code (courtesy of M. Kállay).…”

Section: Theoretical Methods and Computational Detailsmentioning

confidence: 99%

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

Vidal¹,

Epshtein²,

Scutelnic³

et al. 2020

Preprint

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We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys. Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation. The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller effect in benzene cation.

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On the basis set selection for calculations of core-level states: different strategies to balance cost and accuracy

Cited by 56 publications

References 73 publications

Interplay of Open-Shell Spin-Coupling and Jahn–Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

Interplay of Open-Shell Spin-Coupling and Jahn–Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

The nuts and bolts of core-hole constrained ab initio simulation for K-shell x-ray photoemission and absorption spectra

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

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