Comparison for pyrrole and pyrazole of orbital energies and population analyses from ab-initio SCF, CNDO/2, INDO, extended hückel, and ARCANA calculations

The present study reports the theoretical vertical ionization potentials (IPs) for all the valence electrons in six XPY2 molecules by utilizing the corrected orbital energies calculated with three theoretical methods, namely, the ab initio HartreeFock (HF), and both the pure and hybrid density functional theory (DFT) methods at, respectively, the BLYP/6-311+G* and B3lYP/6-311+G* levels of theory. Evaluation of the numerical corrections to the orbital energies was achieved by comparisons with the IP values obtained via explicit computation of the energy differences between the neutral molecules and the corresponding radical cations (the ΔSCF method) and shows values from 0.9 to 1.9 eV for the HF, and positive values from 2.9 to 3.9 eV and from 1.8 to 2.4 eV for the pure and hybrid DFT methods, respectively. In contrast to the orbital energies, the ΔSCF method is shown to give consistent values among the three methods, as well as reasonable agreement with the experimental IP values.Key words: ionization potential, phosphorane, Koopmans' theorem, Janak's theorem.

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ChemInform Abstract: AN ANALYSIS OF THE THROUGH-BOND INTERACTION USING THE LOCALIZED MOLECULAR ORBITALS WITH AB INITIO CALCULATIONS. II. LONE-PAIR ORBITAL ENERGIES IN BICYCLO COMPOUNDS: 7-AZABICYCLO(2.2.1)HEPTANE AND 2-AZABICYCLO(2.2.2)OCTANE, AND THEIR N

Chemischer Informationsdienst ◽

10.1002/chin.198147070 ◽

1981 ◽

Vol 12 (47) ◽

Author(s):

A. IMAMURA ◽

A. TACHIBANA ◽

M. OHSAKU

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Lone Pair ◽

Molecular Orbitals ◽

Localized Molecular Orbitals ◽

Lone Pair Orbital ◽

Orbital Energies ◽

Bond Interaction

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Theoretical Study of Linear NiCO and CuCO and its Implication to Adsorption

Zeitschrift für Naturforschung A ◽

10.1515/zna-1979-0118 ◽

1979 ◽

Vol 34 (1) ◽

pp. 114-116

Author(s):

Hiroyuki Itoh ◽

A. Barry Kunz

Keyword(s):

Ab Initio ◽

Theoretical Study ◽

Ground States ◽

Mo Calculations ◽

Orbital Energies ◽

Bonding Interaction ◽

Level Shifts ◽

The Difference

Abstract Ab initio RHF-MO calculations are made for the linear NiCO and CuCO clusters. The ground states of them involve Ni 3d94s1 and Cu 3d104s1 electron configurations, respectively. The orbital energies of the CO 1 π-like levels in both clusters are closely similar to each other. The CO 5σ-like level shifts toward the CO 17r-like level due to the bonding interaction of the 5σ with the metal 4s and 3dZ2. The results are discussed in relation to the difference of the 3d-level positions and the similarity of 4s levels of Ni and Cu. For NiCO both the 4s and 3d orbitals contribute to the metal-CO binding while for CuCO only the 4 s orbital contributes to it. The present results are in agreement with the UPS experiments on adsorption.

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Photoelektronenspektroskopische Untersuchungen an Bor-Verbindungen, IV1 / Ionisierungsenergien und Geometrie von Tetrazadiborinen Photoelectronspectroscopic Investigations on Boron Compounds, IV1 Ionization Energies and Geometry of Tetrazadiborines

Zeitschrift für Naturforschung B ◽

10.1515/znb-1974-7-806 ◽

1974 ◽

Vol 29 (7-8) ◽

pp. 476-484 ◽

Cited By ~ 21

Author(s):

Jürgen Kroner ◽

Dieter Nölle ◽

Heinrich Nöth ◽

Wolfgang Winterstein

Keyword(s):

Structural Model ◽

Ring System ◽

Boron Compounds ◽

Ionization Energies ◽

Π Interactions ◽

Orbital Energies ◽

Extended Hückel ◽

Twist Form ◽

Derivatives Of ◽

Extended Hückel Calculations

The photoelectron (PE) spectra of five boron-substituted derivatives of tetrazadiborineare presented. They are discussed on the basis of a structural model (twist form of the ring system) which results from simple extended HÜCKEL calculations. Orbital energies calculated by the CNDO/S method agree quite well with observed ionization energies. According to these at least the first three bands correspond to ionizations from π-orbitals. Evidence for strong π-interactions can be deduced by comparison with PE spectra of diaminoboranes.

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