The effect of the choice of parameters on the order of energy levels of benzene calculated in the π-electron approximation by the configuration interaction method including double- and triple-excited configurations

Koutecký, J.; Čı́žek, J.; Dubský, J. V.; Hlavaty, K.

doi:10.1007/bf00526596

Cited by 62 publications

(8 citation statements)

References 14 publications

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“…Effect of semi-empirical parameters and inclusion of different amount of excited configurations on the lower excited singlets of benzene have been thoroughly examined by Koutecky and co-workers [ 6 ] . They observed that the semiempirical parameters play a great deal in the singlet energy levels of this molecule and in such calculation inclusion of configurations higher than the doubly excited ones is not very important.…”

Section: Discussionmentioning

confidence: 99%

“…It has been pointed out by Orloff [3] that this error is very significant in the low energy transitions, so in this paper we intend also to examine the effect of semi-empirical parameters on the triplet energy levels of benzene. We have deliberately omitted the singlet levels because these have already been treated exhaustively [6]. Another purpose of the present paper is to determine the oscillator strength of the reported triplettriplet bands [7,87 in this molecule.…”

Section: Introductionmentioning

confidence: 99%

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Effect of semi‐empirical parameters on the triplet energy levels and triplet–triplet transition in benzene

Sannigrahi

1971

Int J of Quantum Chemistry

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AbstractsTriplet energy levels and triplet-triplet transition in benzene have been calculated semi-empirically by considering CI up to and including doubly excited configurations and using various values of the core resonance and electron repulsion integrals. The usual method of calibrating j3 (core resonance integral) from one of the observed transitions in the semi-empirical methods is critically examined with respect to the triplet levels of this molecule. Semi-empirical parameters are found to have a pronounced effect on the energy of the triplets and the triplet-triplet transitions; but the intensities of such transitions are quite insensitive to the choice of such parameters.Numerical results show several 3B,, + 3E,, transitions of various intensities. Out of these, the transitions which correspond energetically to the observed triplet-triplet bands are found to have low intensity. Some strong triplet-triplet bands are predicted in the far ultra violet region.On a calcult des niveaux d'tnergies de triplets et des transitions triplet-triplet pour le benzhe avec des mtthodes semi-empiriques. Les configurations deux fois excittes ont ttk inclues et des valeurs difftrentes des inttgrales de rtsonance et de rkpulsion ont t t t essaytes. La mtthode ordinaire pour calibrer j3 de l'une des transitions observh a t t t examinke critiquement par rapport aux niveaux triplets de la moltcule. L'hergie des triplets et les difftrences d'tnergie sont t r h sensibles aux choix des param&res, ce qui n'est pas le cas pour les intensit& des transitions.Les rtsultats indiquent plusieurs transitions 3 4 , --+ 3E2, d'intensites difftrentes. Parmi celles-ci, les transitions qui correspondent du point de vue de l'tnergie aux bandes observtes, ont une intensitt faible. Quelques bandes fortes dans la rtgion ultraviolette lointaines sont prtdites.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of semi‐empirical parameters on the triplet energy levels and triplet–triplet transition in benzene

Sannigrahi

1971

Int J of Quantum Chemistry

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“…He was unable to define a "best" set of parameters. In his literature search he seemed not to notice a very similar type of calculation carried out by Czechoslovakian authors (408) .…”

Section: Semiempirical Theories Based On a 2-electronic Hamiltonianmentioning

confidence: 91%

Quantum Theory of Atoms and Molecules

Golebiewski¹,

Taylor²

1967

Annu. Rev. Phys. Chem.

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“…To get some idea about the capability of H I N D 0 with the standard parameters we have compared the measured ionization energies of Ni(C5H5)N0 The discussion of reorganization effects with the help of a variable INDO Hamiltonian in the Green's function formalism is related to various model investigations where the importance of electron correlation, the convergence of perturbational approaches, and the magnitude of correlation energies has been studied in PPP Hamiltonians with flexible parameters. The most important work in this field has been done by McLachlan and Ball [21], Kouteckl et al [22,23], &ek, Paldus, and co-workers [24,25], Karplus and co-workers [26,27], and Malrieu et al in the PCILO framework [28]. On the other hand this contribution also is analogous to theoretical investigations in the solid state, in the theory of nuclear matter, and in atomic systems; e.g., to studies of Coulomb holes in the electron gas [29,30], to self-energy models in the low-density limit for quasiparticles in the theory of nuclear matter [31], and to Brueckner's investigations on atoms in the nonuniform electron gas approximation connecting calculated correlation energies with density gradients [32].…”

Section: Bohmmentioning

confidence: 99%

Reorganization effects in the photoelectron spectra of transition metal compounds: A Green's function study in the framework of a variable INDO hamiltonian

Böhm

1982

Int J of Quantum Chemistry

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The magnitude of reorganization energies in the photoelectron (PE) spectra of various transition metal compounds with Mn, Fe, and Ni as 3d center is studied by means of a variable INDO Hamiltonian. The Koopmans defects are analyzed as a function of the one-electron resonance integral p,, and as function of the one-and two-center electron-electron interaction integrals. p:: has the property of an inverse coupling constant; reorganization effects are enlarged with reduced p;,? values. In the limit of very small resonance integrals a reduction of the calculated Koopmans defects due to modified localization properties of the orbital wave function is encountered. The two-center electron-electron interaction integrals 7:; have been calculated via an exponential formula with a variable range parameter. In the limit of long-range potentials with flattened 7:; gradients a significant reduction of relaxation and correlation is diagnozed; large defects are predicted in the short-range limit with steep gradients in the repulsion potential. The one-center Coulomb and exchange integrals (r:,?, K:,?) have been modified by a multiplicative factor. With enlarged one-center integrals enhanced Koopmans defects are encountered. The reorganization energies are determined by means of a Green's function approach with a renormalized approximation for the self-energy part.

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The effect of the choice of parameters on the order of energy levels of benzene calculated in the π-electron approximation by the configuration interaction method including double- and triple-excited configurations

Cited by 62 publications

References 14 publications

Effect of semi‐empirical parameters on the triplet energy levels and triplet–triplet transition in benzene

Effect of semi‐empirical parameters on the triplet energy levels and triplet–triplet transition in benzene

Quantum Theory of Atoms and Molecules

Reorganization effects in the photoelectron spectra of transition metal compounds: A Green's function study in the framework of a variable INDO hamiltonian

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