Density functional calculations of difluorodiazete structures with Gaussian-orbital-type approach

Jursic, Branko S.

doi:10.1002/(sici)1097-461x(1996)57:2<213::aid-qua7>3.0.co;2-0

Cited by 65 publications

(15 citation statements)

References 22 publications

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“…The potential energy surface (PES) for the dissociation reaction of N 2 O(X 1 Σ + ) was established utilizing various optimization methods, including B3LYP, [29][30][31] M06-2X, 32,33 CCSD, 34,35 and CCSD(T) 36,37 with basis sets of 6-311++G(3df), 38 aug-cc-pVTZ, [39][40][41] and aug-cc-pVTZ+d. 39 In order to achieve more reliable energies for the PES and rate constant predictions, the CCSD(T) method with the extrapolated basis set CBS(TQ5), [42][43][44] denoted as CCSD(T)/CBS(TQ5), was used to compute single-point energies of all species involved.…”

Section: Methodsmentioning

confidence: 99%

Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics

Pham

Tsay

Lin

2020

Int J of Chemical Kinetics

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The spin‐forbidden dissociation reaction of the N2O(X1Σ+) ground state has been investigated by both quantum calculations and experiments. Ab initio prediction at the CCSD(T)/CBS(TQ5)//CCSD(T)/aug‐cc‐pVTZ+d level of theory gave the crossing point (MSX) energy at 60.1 kcal/mol for the N2O(X1Σ+) → N2(X1normalΣg+) + O(3P) transition, in good agreement with published data. The T‐ and P‐dependent rate coefficients, k1(T,P), for the nonadiabatic thermal dissociation predicted by nonadiabatic Rice‐Ramsperger‐Kassel‐Marcus (RRKM) calculations agree very well with literature data. The rate constants at the high‐ and low‐pressure limits, k1∞ = 1011.90 exp (−61.54 kcal mol−1/RT) s−1 and k1o = 1014.97 exp(−60.05 kcal mol−1/RT) cm3 mol−1 s−1, for example, agree closely with the extrapolated results of Röhrig et al. at both pressure limits. The second‐order rate constant (k1o) is also in excellent agreement with our result measured by FTIR spectrometry in the present study for the temperature range of 860‐1023 K as well as with many existing high‐temperature data obtained primarily by shock‐wave heating up to 3340 K. Kinetic modeling of the NO product yields measured at long reaction times in the present work also allowed us to reliably estimate the rate constant for reaction (3), O + N2O → N2 + O2, based on its strong competition with the NO formation from reaction (2) which has been better established. The modeled values of k3 confirmed the previous finding by Davidson et al. with significantly smaller values of A‐factor and activation energy than the accepted ones. A least‐squares analysis of both sets of data gave k3 = 1012.22 ± 0.04 exp[− (11.65 ± 0.24 kcal mol−1/RT)] cm3 mol−1 s−1, covering the wide temperature range of 988‐3340 K.

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Section: Methodsmentioning

confidence: 99%

Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics

Pham

Tsay

Lin

2020

Int J of Chemical Kinetics

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“…However, molecular orbital calculations with reliable basis sets larger than 6-31G* at this level of theory are still a formidable task for larger molecules. Recent theoretical studies − show that the density functional theory (DFT) is becoming an alternative to ab initio methods since it is sufficiently accurate and applicable to any system of interest, even for larger molecules. DFT is practically a much cheaper technique than conventional ab initio methods, especially in terms of the electron correlation.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on Salicylaldehyde and 2-Mercaptobenzaldehyde: Intramolecular Hydrogen Bonding

Chung

Kwon

1998

J. Phys. Chem. A

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The molecular structures and the intramolecular hydrogen bonding for salicylaldehyde and 2-mercaptobenzaldehyde have been investigated with both ab initio and density functional theory methods. We have considered the several possible conformations with respect to the rotation of two functional groups in a given molecule not only to understand the conformational behaviors but also to estimate the energy of intramolecular hydrogen bonding. The optimized geometrical parameters for salicylaldehyde at the B3LYP levels and the computed 1H NMR chemical shifts for 2-mercaptobenzaldehyde at the B3LYP/6-31+G* optimized geometry are in good agreement with those of previous experimental data. The results show that the inclusion of electron correlation at the B3LYP levels is more crucial in comparing the relative stability among the conformers of 2-mercaptobenzaldehede than among the conformers of salicylaldehede. The hydrogen-bonding energies are estimated by comparing the molecular energies between two different conformations either with a hydrogen bond or with no hydrogen bond of a given molecule. These energies for salicylaldehyde and 2-mercaptobenzaldehyde are computed to be about 9 and 2 kcal/mol at the B3LYP levels, respectively.

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“…Therefore, it is reasonable to employ B3LYP/6-311G* as a practical tool for modeling molecular structures and computing energetic data of Se-containing molecules studied in this work. This forecast can also be supported by the initiative that for small organic systems B3LYP method can give more reliable results than higher level ab initio methods [65][66][67][68][69]. In addition, density functional theory (DFT) calculations (1), where X = F, Cl, Br, CH 3 , OCH 3 , CF 3 , CN, and NH 2 ; Y = Me, Et, and i-Pr have been applied successfully to a number of problems in chalcogen-nitrogen chemistry [70][71][72][73][74].…”

Section: Resultsmentioning

confidence: 79%

On the selenepin/benzene selenide valence tautomerizations: electronic and steric effects at theoretical levels

2009

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Tautomerization in selenepin (1) benzene selenide (2) binary system is found to favor, 2, at HF, MP2, and B3LYP levels, using 6-311G* basis set. Electronic effects appear to have small effects on 1 2 equilibria and show little impact on the conformational ring inversions of 1, at the same levels. In contrast, steric effects effectively decrease DH values in an order inversely proportional to the size of the substituents employed (Me [ Et [ i-Pr). A possible Se extrusion is suggested to be the main reason why no 2 has ever been detected experimentally.

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Density functional calculations of difluorodiazete structures with Gaussian-orbital-type approach

Cited by 65 publications

References 22 publications

Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics

Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics

Theoretical Study on Salicylaldehyde and 2-Mercaptobenzaldehyde: Intramolecular Hydrogen Bonding

On the selenepin/benzene selenide valence tautomerizations: electronic and steric effects at theoretical levels

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Density functional calculations of difluorodiazete structures with Gaussian-orbital-type approach

Cited by 65 publications

References 22 publications

Thermal decomposition of N2O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(3P) formation kinetics

Thermal decomposition of N2O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(3P) formation kinetics

Theoretical Study on Salicylaldehyde and 2-Mercaptobenzaldehyde: Intramolecular Hydrogen Bonding

On the selenepin/benzene selenide valence tautomerizations: electronic and steric effects at theoretical levels

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Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics

Thermal decomposition of N₂O near 900 K studied by FTIR spectrometry: Comparison of experimental and theoretical O(³P) formation kinetics