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Søren Vrønning Hoffmann

The ionic states of cyclooctatetraene. Analysis of a new experimental photoelectron spectrum by ab initio and density functional methods

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The ionic states of cyclooctatetraene. Analysis of a new experimental photoelectron spectrum by ab initio and density functional methods. / Palmer, Michael H.; Coreno, Marcello; De Simone, Monica; Grazioli, Cesare; Hoffmann, Søren Vrønning; Jones, Nykola C.

I: The Journal of Chemical Physics, Bind 150, Nr. 19, 194305, 2019.

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

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Palmer, Michael H. ; Coreno, Marcello ; De Simone, Monica ; Grazioli, Cesare ; Hoffmann, Søren Vrønning ; Jones, Nykola C. / The ionic states of cyclooctatetraene. Analysis of a new experimental photoelectron spectrum by ab initio and density functional methods. I: The Journal of Chemical Physics. 2019 ; Bind 150, Nr. 19.

Bibtex

@article{52a8c818c63d401c91c1d1e8db27bd4d,
title = "The ionic states of cyclooctatetraene. Analysis of a new experimental photoelectron spectrum by ab initio and density functional methods",
abstract = "A synchrotron-based study of the photoelectron spectrum (PES) for cyclooctatetraene (COT) is reported, and this has been subjected to theoretical analysis in unprecedented detail. Weak vibrational structure was observed on the lowest ionization energy (IE 1 ), but the peaks generally show very broad features. Multiconfiguration self-consistent field study confirms that the adiabatic IE (AIE) sequence is 1 2 A 1 < 1 2 B 1 < 2 2 A 1 < 1 2 A 2 < 2 2 B 1 < 3 2 A 1 . The Tamm-Dancoff approximation gives an acceptable interpretation of the PES below 20 eV. Vibrational analysis of the PES bands by Franck-Condon methods predicts well-defined vibrational structure for these ionic states. The principal contributors to the PES envelopes are the a 1 modes, and only a few are responsible for the overall shape of most bands. The high density of vibrational states, together with the known D 2d D 2d interconversion process, where the C=C and C-C bonds interchange, is attributed to the lack of the observed structure. The transition state (TS) structures for the interconversion above of several ionic states of COT have been elucidated. The intrinsic reaction coordinate procedure gave a planar TS for the X 1 A 1 (D 2d ) 1 A 1g (D 4h ) X 1 A 1 (D 2d ) process; this shows alternating C-C (1.4791 {\AA}), C=C (1.3261 {\AA}), and C-H (1.0780 {\AA}) bond lengths. The planar TS is a very shallow maximum, with energy varying with the method used, Hartree-Fock 0.575 eV and second order M{\o}ller-Plesset 0.653 eV. A polynomial containing quadratic, quartic, and sextic terms gives an effectively exact fit to the surface. The lowest ionic state of COT (X 2 A 1 ) shows a similar TS for the process X 2 A 1 (D 2d ) 2 B 2u (D 4h ). This structure has alternating C-C (1.4366 {\AA}), C=C (1.3572 {\AA}), and C-H (1.0756 {\AA}) bonds. ",
keywords = "APPROXIMATION, ATOMS, BASIS-SETS, BOND SHIFT KINETICS, NMR, VALENCE",
author = "Palmer, {Michael H.} and Marcello Coreno and {De Simone}, Monica and Cesare Grazioli and Hoffmann, {S{\o}ren Vr{\o}nning} and Jones, {Nykola C.}",
year = "2019",
doi = "10.1063/1.5096254",
language = "English",
volume = "150",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "AMER INST PHYSICS",
number = "19",

}

RIS

TY - JOUR

T1 - The ionic states of cyclooctatetraene. Analysis of a new experimental photoelectron spectrum by ab initio and density functional methods

AU - Palmer, Michael H.

AU - Coreno, Marcello

AU - De Simone, Monica

AU - Grazioli, Cesare

AU - Hoffmann, Søren Vrønning

AU - Jones, Nykola C.

PY - 2019

Y1 - 2019

N2 - A synchrotron-based study of the photoelectron spectrum (PES) for cyclooctatetraene (COT) is reported, and this has been subjected to theoretical analysis in unprecedented detail. Weak vibrational structure was observed on the lowest ionization energy (IE 1 ), but the peaks generally show very broad features. Multiconfiguration self-consistent field study confirms that the adiabatic IE (AIE) sequence is 1 2 A 1 < 1 2 B 1 < 2 2 A 1 < 1 2 A 2 < 2 2 B 1 < 3 2 A 1 . The Tamm-Dancoff approximation gives an acceptable interpretation of the PES below 20 eV. Vibrational analysis of the PES bands by Franck-Condon methods predicts well-defined vibrational structure for these ionic states. The principal contributors to the PES envelopes are the a 1 modes, and only a few are responsible for the overall shape of most bands. The high density of vibrational states, together with the known D 2d D 2d interconversion process, where the C=C and C-C bonds interchange, is attributed to the lack of the observed structure. The transition state (TS) structures for the interconversion above of several ionic states of COT have been elucidated. The intrinsic reaction coordinate procedure gave a planar TS for the X 1 A 1 (D 2d ) 1 A 1g (D 4h ) X 1 A 1 (D 2d ) process; this shows alternating C-C (1.4791 Å), C=C (1.3261 Å), and C-H (1.0780 Å) bond lengths. The planar TS is a very shallow maximum, with energy varying with the method used, Hartree-Fock 0.575 eV and second order Møller-Plesset 0.653 eV. A polynomial containing quadratic, quartic, and sextic terms gives an effectively exact fit to the surface. The lowest ionic state of COT (X 2 A 1 ) shows a similar TS for the process X 2 A 1 (D 2d ) 2 B 2u (D 4h ). This structure has alternating C-C (1.4366 Å), C=C (1.3572 Å), and C-H (1.0756 Å) bonds.

AB - A synchrotron-based study of the photoelectron spectrum (PES) for cyclooctatetraene (COT) is reported, and this has been subjected to theoretical analysis in unprecedented detail. Weak vibrational structure was observed on the lowest ionization energy (IE 1 ), but the peaks generally show very broad features. Multiconfiguration self-consistent field study confirms that the adiabatic IE (AIE) sequence is 1 2 A 1 < 1 2 B 1 < 2 2 A 1 < 1 2 A 2 < 2 2 B 1 < 3 2 A 1 . The Tamm-Dancoff approximation gives an acceptable interpretation of the PES below 20 eV. Vibrational analysis of the PES bands by Franck-Condon methods predicts well-defined vibrational structure for these ionic states. The principal contributors to the PES envelopes are the a 1 modes, and only a few are responsible for the overall shape of most bands. The high density of vibrational states, together with the known D 2d D 2d interconversion process, where the C=C and C-C bonds interchange, is attributed to the lack of the observed structure. The transition state (TS) structures for the interconversion above of several ionic states of COT have been elucidated. The intrinsic reaction coordinate procedure gave a planar TS for the X 1 A 1 (D 2d ) 1 A 1g (D 4h ) X 1 A 1 (D 2d ) process; this shows alternating C-C (1.4791 Å), C=C (1.3261 Å), and C-H (1.0780 Å) bond lengths. The planar TS is a very shallow maximum, with energy varying with the method used, Hartree-Fock 0.575 eV and second order Møller-Plesset 0.653 eV. A polynomial containing quadratic, quartic, and sextic terms gives an effectively exact fit to the surface. The lowest ionic state of COT (X 2 A 1 ) shows a similar TS for the process X 2 A 1 (D 2d ) 2 B 2u (D 4h ). This structure has alternating C-C (1.4366 Å), C=C (1.3572 Å), and C-H (1.0756 Å) bonds.

KW - APPROXIMATION

KW - ATOMS

KW - BASIS-SETS

KW - BOND SHIFT KINETICS

KW - NMR

KW - VALENCE

U2 - 10.1063/1.5096254

DO - 10.1063/1.5096254

M3 - Journal article

C2 - 31117784

VL - 150

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 19

M1 - 194305

ER -