Hartree-Fock instabilities and electronic properties

Dehareng, Dominique; Dive, Georges

doi:10.1002/(sici)1096-987x(20000430)21:6<483::aid-jcc7>3.0.co;2-o

Cited by 38 publications

(23 citation statements)

References 58 publications

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“…Transition states for the oxidation of various sulfur compounds by peroxides or other compounds containing an active oxygen have been found to show a triplet instability 35, 36, 38, 43, 44. Furthermore, such instabilities seem to be more common as one would expect 45. Consequently, it appears appropriate to address first the question of wave function stability.…”

Section: Resultsmentioning

confidence: 99%

Redox chemistry of organoselenium compounds: Ab initio and density functional theory calculations on model systems for transition states and intermediates of the redox cycle of selenoenzymes

Benková

Kóňa

Gann

et al. 2002

Int J of Quantum Chemistry

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Ab initio [Hartree-Fock (HF)] and density functional theory (B3LYP) ECPcalculations on intermediates and transition states of the reduction of phenylseleninic acid with hydrogen sulfide and of seleninic acid with benzenethiol as models for the species involved in the redox cycle of selenoenzymes are presented. Selenenyl sulfide is found to be the final product of the reduction reaction with sulfides. Further reduction to the selenol requires surmounting a substantial barrier (∼50 kcal mol −1 ). The final step of the redox cycle-oxidation of the selenol by hydrogen peroxide-is strongly exothermic. In case of the unsubstituted derivative H 2 Se three mechanisms for this oxidation are found [concerted and stepwise 1,2-hydrogen and oxygen shift (TS6A, TS6B, resp.) and a four-membered transition state TS6C]. For the oxidation of phenylselenol only TS6A and TS6B are obtained. For nearly all calculated structures the HF wave functions show a triplet instability. In contrast, at the B3LYP level only TS6C has a significant triplet instability. On the basis of QCISD(T)//QCISD results a mechanism involving TS6C seems highly unlikely.

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Section: Resultsmentioning

confidence: 99%

Redox chemistry of organoselenium compounds: Ab initio and density functional theory calculations on model systems for transition states and intermediates of the redox cycle of selenoenzymes

Benková

Kóňa

Gann

et al. 2002

Int J of Quantum Chemistry

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“…, 15, respectively). The electronic structure of the optimized clusters appears to be dependent on the starting electron density matrix, which might be attributed to the Hartree-Fock instability of the solution [20]. Being aware of the problem's ambiguity (it is still neither proved nor objected whether this problem is a numerical calculation artifact or an intrinsic property of certain systems), we have performed the full optimization procedure for the UHF S z = 0 state for all clusters simulated, starting from density matrices obtained for the corresponding clusters in higher S z states (further referred to as ''UHF S z = 0 from higher multiplicities").…”

Section: Methodsmentioning

confidence: 99%

High multiplicity states in disordered carbon systems: Ab initio and semiempirical study

Khavryuchenko

Lisnyak

2010

Chemical Physics

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“…The neutral structures were optimized at the restricted Hartree‐Fock (RHF) level of theory, whereas the deprotonated (anionic) were optimized at the unrestricted Hartree‐Fock level (UHF), both with a 6‐31G(d) basis set 9. It is important to mention that the RHF to UHF stability of the SCF solutions was tested for the anionic molecules 10–13.…”

Section: Theoretical Detailsmentioning

confidence: 99%

Electronic and physicochemical properties of selected nitrofurans: A theoretical study

Soriano-Correa¹,

Raya

Sánchez-Ruiz³

et al. 2005

Int J of Quantum Chemistry

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ABSTRACT:A relationship between the chemical structure and antibacterial activity of nitrofurans is not still completely elucidated; however, from a therapeutics point of view it has been observed that the position of the nitro group is a relevant feature for them to show antibacterial activity. In this work, we performed an ab initio study of some selected nitrofurans at the Hartree-Fock, second-order Møller-Plesset, and Density Functional levels of theory with the purpose of obtaining several electronic structural and physicochemical properties of nitrofurans. The relative acidity of the azomethine group of nitrofurans was analyzed through the deprotonation energy. The results reveal that the less acidic molecules possess antibacterial activity. The bond order analysis suggests that the activity of the nitrofurans could be affected by the electroattracting properties of the substituent. An atomic charge and electrostatic potential analysis showed that the azomethine group, the nitro group, and the furenic ring are influenced by the substituent electronegativity. Finally, a structural analysis showed that the nitro group is coplanar with respect to the furenic ring. The present study reveals that the analyzed physicochemical and structural properties may be related to the antibacterial activity of these nitrofuran-type compounds.

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Hartree-Fock instabilities and electronic properties

Cited by 38 publications

References 58 publications

Redox chemistry of organoselenium compounds: Ab initio and density functional theory calculations on model systems for transition states and intermediates of the redox cycle of selenoenzymes

Redox chemistry of organoselenium compounds: Ab initio and density functional theory calculations on model systems for transition states and intermediates of the redox cycle of selenoenzymes

High multiplicity states in disordered carbon systems: Ab initio and semiempirical study

Electronic and physicochemical properties of selected nitrofurans: A theoretical study

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