Evaluation of density functional theory in the bond rupture of octane

Goldstein, Elisheva; Haught, Mark B.; Tang, Yongchun

doi:10.1002/(sici)1096-987x(19980130)19:2<154::aid-jcc8>3.0.co;2-t

Cited by 6 publications

(8 citation statements)

References 56 publications

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“…DFT methods have been demonstrated to be a good alternative both in computational efficiency and in a more balanced treatment of open-and closed-shell systems (Goldstein et al, 1996;Foresman and Frisch, 1996;Petersson, 1997). For example, the calculated BDE of the C-C bond in ethane is 94.5 kcal/mol at the B3LYP/6-31G* level, which is in better agreement with the experimental result (90.4 kcal/mol) than with the corresponding PMP2 result (96.2 kcal/mol).…”

Section: Resultsmentioning

confidence: 52%

“…The average BDEs for octane homolytic C-C scission are 98 kcal/mol at MP2/6-31G*, 95 kcal/mol at PMP2/ 6-31G*(with spin-projection correction), 90 kcal/mol at B3LYP/6-31G*, and 89 kcal/mol at CBS-4. Again the MP2 results are a bit high compared to experimental BDE (85-87 kcal/mol) derived from Benson's additivity scheme (Goldstein et al, 1996), while the B3LYP and CBS-4 results are in much better agreement with the experimental BDE. Goldstein et al (1996) have carried out a detailed study of the BDEs of octane using both UHF and DFT methods, and they have also included the zero-point energy and temperature corrections.…”

Section: Resultsmentioning

confidence: 63%

“…Melius and co-workers have developed the BAC-MP4 method and have applied it to the thermochemistry of small molecule decomposition (Melius, 1990). Goldstein et al (1996) applied both density functional theory (DFT) and Hartree-Fock (HF) methods to calculate the bond dissociation energy (BDE) of octane cracking. Obviously, there is a need to understand the detailed reaction pathways of the elementary reactions involved in the overall HC thermal cracking.…”

Section: Introductionmentioning

confidence: 99%

“…That is, so far most of the theoretical studies on HC thermal cracking have been limited to small molecules which only contain a few nonhydrocarbon atoms (see Francisco and Montgomery, 1996 for a recent review). Another aspect is that although computational chemistry has been applied to calculate the bond dissociation energies (Jursic, 1996;Liu et al, 1996;Goldstein et al, 1996) and the transition states of hydrocarbon transfer reactions (Heuts et al, 1996;Lee and Masel, 1996;Luo et al, 1997;Tanaka et al, 1996), the structures and energetics of the radical decomposition (β scission) and addition reactions have not been fully addressed.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the Kinetics and Mechanisms of Hydrocarbon Thermal Cracking: An Ab Initio Approach

Xiao

Longo

Hieshima

et al. 1997

Ind. Eng. Chem. Res.

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Unrestricted Hartree-Fock and density functional theory calculations have been carried out to investigate the detailed kinetics and mechanisms of hydrocarbon thermal cracking. The calculations of the elementary reactions involved in the overall cracking of paraffin molecules agree well with the generally accepted free radical mechanism. The results can be summarized as follows: (1) Initiation cracking, the calculated bond dissociation energy (BDE) for C-C homolytic scission is ∼95 kcal/mol at the MP2/6-31G* level and ∼89 kcal/mol at the B3LYP/6-31G* level. No transition states are found in the reactions. (2) H-transfer reaction, the calculated energy barriers (activation energy) are 15-17 kcal/mol at the MP2/6-31G* level and 10-12 kcal/ mol at the B3LYP level. The reverse reaction has about the same energy barrier. The calculated transition state structures for both reactions lie in the middle between the reactant and product.(3) Radical decomposition-"β scission", the activation energy for the radical decomposition is calculated to be 30-33 kcal/mol. The activation energy for the reverse addition reaction is 5 kcal/mol. The optimized transition state structure is product-like for the radical decomposition reaction and reactant-like for the addition reaction.

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Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the Kinetics and Mechanisms of Hydrocarbon Thermal Cracking: An Ab Initio Approach

Xiao

Longo

Hieshima

et al. 1997

Ind. Eng. Chem. Res.

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“…This system of equations can be integrated in time, and can provide a wealth of information regarding the reaction conditions needed to maximize the desired product fractions. 16,19,20 In addition, the number of candidate reactions and transition states grows rapidly with molecular size, making it less likely that Arrhenius parameters for all of the candidate reactions can be predicted and evaluated directly. 1,8,11,12,15 Many important reactions are not easily studied experimentally, and consequently most kinetic models lack well-defined parameters.…”

Section: Introductionmentioning

confidence: 99%

Parallel replica dynamics with a heterogeneous distribution of barriers: Application to n-hexadecane pyrolysis

Kum

Dickson

Stuart

et al. 2004

The Journal of Chemical Physics

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Parallel replica dynamics simulation methods appropriate for the simulation of chemical reactions in molecular systems with many conformational degrees of freedom have been developed and applied to study the microsecond-scale pyrolysis of n-hexadecane in the temperature range of 2100-2500 K. The algorithm uses a transition detection scheme that is based on molecular topology, rather than energetic basins. This algorithm allows efficient parallelization of small systems even when using more processors than particles (in contrast to more traditional parallelization algorithms), and even when there are frequent conformational transitions (in contrast to previous implementations of the parallel replica algorithm). The parallel efficiency for pyrolysis initiation reactions was over 90% on 61 processors for this 50-atom system. The parallel replica dynamics technique results in reaction probabilities that are statistically indistinguishable from those obtained from direct molecular dynamics, under conditions where both are feasible, but allows simulations at temperatures as much as 1000 K lower than direct molecular dynamics simulations. The rate of initiation displayed Arrhenius behavior over the entire temperature range, with an activation energy and frequency factor of E(a) = 79.7 kcal/mol and log A/s(-1) = 14.8, respectively, in reasonable agreement with experiment and empirical kinetic models. Several interesting unimolecular reaction mechanisms were observed in simulations of the chain propagation reactions above 2000 K, which are not included in most coarse-grained kinetic models. More studies are needed in order to determine whether these mechanisms are experimentally relevant, or specific to the potential energy surface used.

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Petroleum Geochemistry

Tang²

2016

Molecular Modeling of Geochemical Reactions

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Evaluation of density functional theory in the bond rupture of octane

Cited by 6 publications

References 56 publications

Understanding the Kinetics and Mechanisms of Hydrocarbon Thermal Cracking: An Ab Initio Approach

Understanding the Kinetics and Mechanisms of Hydrocarbon Thermal Cracking: An Ab Initio Approach

Parallel replica dynamics with a heterogeneous distribution of barriers: Application to n-hexadecane pyrolysis

Petroleum Geochemistry

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