Stabilized Koopmans' Theorem Calculations on the .pi.* Temporary Anion States of Benzene and Substituted Benzenes

Chen, C.-S.; Feng, Tai; Chao, Jeng Shiow‐Yau

doi:10.1021/j100021a029

Cited by 23 publications

(12 citation statements)

References 3 publications

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“…j This is true particularly for LUMO dominated conduction, because the HF is notoriously inadequate for electron affinities. [145][146][147][148] . See 139 for further discussion of this point.…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

ELECTRONTRANSMISSIONTHROUGHMOLECULES ANDMOLECULARINTERFACES

Nitzan

2001

Annu. Rev. Phys. Chem.

910

881

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Electron transmission through molecules and molecular interfaces has been a subject of intensive research due to recent interest in electron-transfer phenomena underlying the operation of the scanning-tunneling microscope on one hand, and in the transmission properties of molecular bridges between conducting leads on the other. In these processes, the traditional molecular view of electron transfer between donor and acceptor species gives rise to a novel view of the molecule as a current-carrying conductor, and observables such as electron-transfer rates and yields are replaced by the conductivities, or more generally by current-voltage relationships, in molecular junctions. Such investigations of electrical junctions, in which single molecules or small molecular assemblies operate as conductors, constitute a major part of the active field of molecular electronics. In this article I review the current knowledge and understanding of this field, with particular emphasis on theoretical issues. Different approaches to computing the conduction properties of molecules and molecular assemblies are reviewed, and the relationships between them are discussed. Following a detailed discussion of static-junctions models, a review of our current understanding of the role played by inelastic processes, dephasing and thermal-relaxation effects is provided. The most important molecular environment for electron transfer and transmission is water, and our current theoretical understanding of electron transmission through water layers is reviewed. Finally, a brief discussion of overbarrier transmission, exemplified by photoemission through adsorbed molecular layers or low-energy electron transmission through such layers, is provided. Similarities and differences between the different systems studied are discussed.

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Section: Quantum Chemical Calculationsmentioning

confidence: 99%

ELECTRONTRANSMISSIONTHROUGHMOLECULES ANDMOLECULARINTERFACES

Nitzan

2001

Annu. Rev. Phys. Chem.

910

881

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“…Among most preeminent approaches in this direction are the electron propagation theory (through considering the self-energy operator) [46];disproving the existence of ionization potential as the lowest eigenvalues of KT but generalizing it to the arbitrarily close value to IP [43]; interpreting the self-consistent Hartree-Fock field as coupled harmonic oscillators evolving in a nonlinear potential [47]; variationally extending KT to restricted open-sells canonical orbitals which nevertheless overestimate the Aufbau principle [48]; differentiating between vertical and adiabatic ionization potentials for the strongest line of the band and for the 0 → 0 band transition, respectively [49]; establishing the connection with DFT through Janak's theorem and proving its reliability for large molecular systems (including fullerenes or boron nitride nanotubes B 48 N 48 ) [50]; including the negative electron affinity extensions within DFT for halogenated small organic molecules [51]; establishing the direct connection of the frontier orbitals with the pi-electrons and of the electronic transfer of conjugated aromatic systems [52];driving the electronic transfer in alfa-substituted organic polymers [53], providing with optical spectra analysis for intervalence complexes formed by organic bridges between radical ions [54]; till the modeling of anti-inflammatory activities of clinical drugs acting through ionization processes in special [55] and by chemical reactivity indices and DFT in general [56–62]. …”

Section: Introductionmentioning

confidence: 99%

“…till the modeling of anti-inflammatory activities of clinical drugs acting through ionization processes in special [55] and by chemical reactivity indices and DFT in general [56–62]. …”

Section: Introductionmentioning

confidence: 99%

Koopmans′ Analysis of Chemical Hardness with Spectral‐Like Resolution

Putz

2013

The Scientific World Journal

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Three approximation levels of Koopmans' theorem are explored and applied: the first referring to the inner quantum behavior of the orbitalic energies that depart from the genuine ones in Fock space when the wave-functions' Hilbert-Banach basis set is specified to solve the many-electronic spectra of spin-orbitals' eigenstates; it is the most subtle issue regarding Koopmans' theorem as it brings many critics and refutation in the last decades, yet it is shown here as an irrefutable “observational” effect through computation, specific to any in silico spectra of an eigenproblem; the second level assumes the “frozen spin-orbitals” approximation during the extracting or adding of electrons to the frontier of the chemical system through the ionization and affinity processes, respectively; this approximation is nevertheless workable for great deal of chemical compounds, especially organic systems, and is justified for chemical reactivity and aromaticity hierarchies in an homologue series; the third and the most severe approximation regards the extension of the second one to superior orders of ionization and affinities, here studied at the level of chemical hardness compact-finite expressions up to spectral-like resolution for a paradigmatic set of aromatic carbohydrates.

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“…More accurate methods can be useful for answering questions of geometry optimization as well as the change of molecular energy levels after contact with metal. Stabilization techniques in combination with Koopman's theorem have been very successful in predicting energies of anions for several molecules, such as benzene and substituted benzenes, 49 cyanoethylenes, 50 or linear silanes. 51 However, even in those cases, an overall energy uncertainty remains and empirical adjustments based on experiments are needed.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, the Hartree-Fock small basis calculation is far less accurate for affinity levels than for occupied ones. [47][48][49][50] In terms familiar from electron transfer reactions, 53 we expect our calculations to be far more accurate for hole-type than for electron-type superexchange.…”

Section: Molecular Descriptionmentioning

confidence: 99%