Coupled Cluster and Quantum Monte-Carlo potential energy curves of the ground state of Be 2 and Be 2 + molecules

Nasiri, Saeed; Zahedi, Mansour

doi:10.1016/j.comptc.2017.04.009

Cited by 4 publications

(4 citation statements)

References 66 publications

(112 reference statements)

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“…To my best knowledge, the atoms Be and Mg and their “exotic” dimers Be 2 and Mg 2 have never been tested for CPE and ENE. The Be 2 is known for its unique bonding characteristics . The σ‐ bond is hybridized and calculated to contain 2p contributions of 30% .…”

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

“…The σ‐ bond is hybridized and calculated to contain 2p contributions of 30% . The vertical ionization energy is I 0, v = 7.483 . While Be – is unstable, Be 2 can attach an electron, and its electron affinity is A 0, a (Be 2 ) = 0.499 .…”

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

“…The energy difference between XY and XY + is obtained from (i) theoretical calculations, for example, Refs. [] (ii) molecular photoelectron (PE) spectra, for example, Refs. [] The PE spectra are often assigned to the electron removal from a particular bond, b , for example, Refs.…”

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

“…The updated I and A data are listed in Supporting Information Table S, for their references, see Refs. [].…”

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

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Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

Szentpály

2018

J Comput Chem

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The chemical potential is by definition constant in molecules, and electronic charge is in principle equilibrated by bonding. Does electronegativity offer the best scale to unify these principles? According to conceptual density functional theory (c-DFT), the electronegativity equalization (ENE) and chemical potential equalization (CPE) principles seem rigorous and identical. However, the operational formulations of CPE and ENE fail to validate this claim, and frequently dramatic deviations from equalization are reported. We here eliminate the deviations to a very large extent. The problems originate from (i) c-DFT's exclusive reference to ground states and violations of the Wigner-Witmer symmetry constraints for bonding, (ii) electron self-interaction and delocalization errors. The problems are solved, and much more accurate ENE and bond polarities are obtained by replacing the ground-state electronegativity (χ ) by the valence-state electronegativity (χ ) and its generalization, the valence-pair-affinity (VPA, α ). The VPA is a charge dependent pair-sharing potential connected to Ruedenberg's bond theory that emphasizes the role of electron pair-density. The performances of the valence-pair equilibration (VPEq) and c-DFT's operational CPE are compared for 89 molecules with very diverse bond characters, including the "exotic" dimers Be , Mg , B , C , and Mn . The accuracy of VPEq is about 9 times better than that of operational CPE. Without requiring ad hoc calibrations, the VPEq bond polarities agree very well with results of state-of-the-art population analyses, and charges derived from vibrational spectra. A paradigm shift emphasizing valence states seems in order for c-DFT. Electronegativity and the chemical potential should be regarded as separate properties. Copyright © 2018 Wiley Periodicals, Inc.

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Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

“…The updated I and A data are listed in Supporting Information Table S, for their references, see Refs. [].…”

Section: The Performance Of Valence‐pair Equilibrationmentioning

confidence: 99%

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Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

Szentpály

2018

J Comput Chem

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Quantum Monte Carlo simulations using Slater-Jastrow-backflow wave function

Nasiri

Zahedi

2020

Computational and Theoretical Chemistry

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Ab initio electronic structure of the Sr2+ molecular ion

Śmiałkowski

Korona

Tomza

2020

J. Phys. B: At. Mol. Opt. Phys.

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Molecular ions formed in cold hybrid ion-atom experiments may find interesting applications ranging from precision measurements to controlled chemical reactions. Here, we investigate electronic structure of the Sr + 2 molecular ion, which may be produced by photoassociation of laser-cooled Sr + ions immersed into an ultracold gas of Sr atoms or by ionization of ultracold Sr2 molecules. Using ab initio electronic structure methods, such as the coupled cluster and configuration interaction ones with small-core relativistic energy-consistent pseudopotentials and large Gaussian basis sets, we calculate potential energy curves for the ground and 41 excited electronic states, and electric dipole transition moments between them. We show that alkaline-earth molecular ions despite of their apparently simple structure with three valence electrons only are challenging for state-of-the-art quantum chemistry methods due to their multireference nature and high density of states. Finally, we calculate and analyze Franck-Condon factors governing the photoionization of ground-state Sr2 molecules into 2 Σ + u and 2 Σ + g states of Sr + 2 molecular ions. The present results may be useful for studying and guiding formation and spectroscopy of cold Sr + 2 molecular ions.

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Coupled Cluster and Quantum Monte-Carlo potential energy curves of the ground state of Be 2 and Be 2 + molecules

Cited by 4 publications

References 66 publications

Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

Eliminating symmetry problems in electronegativity equalization and correcting self‐interaction errors in conceptual DFT

Quantum Monte Carlo simulations using Slater-Jastrow-backflow wave function

<i>Ab initio</i> electronic structure of the Sr<sub>2</sub><sup>+</sup> molecular ion

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