Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Wang, Li; Zhao, Yuan; Zhang, Jinglai

doi:10.1016/j.jfluchem.2011.01.009

Cited by 7 publications

(9 citation statements)

References 37 publications

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“…It can be seen that although most of the computed quantities listed in Table 1, obtained using the MPW1K functional with the two different basis sets (6‐31+G** in the present work and 6‐311+G** from Ref. [47]), are very similar, the computed TS imaginary vibrational frequencies differ by 88i cm −1 , suggesting that basis set effects on the shape of the computed MEPs near the TS are not insignificant. In addition, computed CVT/SCT k values obtained with the G3(MP2)//MPW1K/6‐311+G** dual level MEP from reference [47] agree very well with available experimental k values from Ref.…”

Section: Discussionmentioning

confidence: 59%

“…[47]), are very similar, the computed TS imaginary vibrational frequencies differ by 88i cm −1 , suggesting that basis set effects on the shape of the computed MEPs near the TS are not insignificant. In addition, computed CVT/SCT k values obtained with the G3(MP2)//MPW1K/6‐311+G** dual level MEP from reference [47] agree very well with available experimental k values from Ref. [2] (fitted to an Arrhenius expression; see Ref.…”

Section: Discussionmentioning

confidence: 91%

“…Lastly, during the preparation of the present manuscript, a computational study on the rate constants of the hydrogen abstraction reactions of CF 3 CHFCF 3 + H [i.e., reaction (1) in this study] and CF 3 CF 2 CHF 2 + H has appeared. [47] The MEP computed at the G3(MP2)//MPW1K/6‐311+G** dual level was used in TST, CVT, and CVT/SCT calculations of k over a temperature range of 200–2000 K. Some computed ab inito /DFT results reported in this study for reaction (1) are included in Table 1 for comparison, particularly because the MPW1K functional has also been used in this study, but with a different basis set from that in Ref. [47].…”

Section: Discussionmentioning

confidence: 99%

“…[47] The MEP computed at the G3(MP2)//MPW1K/6‐311+G** dual level was used in TST, CVT, and CVT/SCT calculations of k over a temperature range of 200–2000 K. Some computed ab inito /DFT results reported in this study for reaction (1) are included in Table 1 for comparison, particularly because the MPW1K functional has also been used in this study, but with a different basis set from that in Ref. [47]. It can be seen that although most of the computed quantities listed in Table 1, obtained using the MPW1K functional with the two different basis sets (6‐31+G** in the present work and 6‐311+G** from Ref.…”

Section: Discussionmentioning

confidence: 99%

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Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Mok

Lee

et al. 2012

J Comput Chem

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The minimum energy path (MEP) of the reaction, CF3CHFCF3 + H → transition state (TS) → CF3CFCF3 + H2, has been computed at different ab initio levels and with density functional theory (DFT) using different functionals. The computed B3LYP/6‐31++G**, BH&HLYP/cc‐pVDZ, BMK/6‐31++G**, M05/6‐31+G**, M05‐2X/6‐31+G**, UMP2/6‐31++G**, PUMP2/6‐31++G**//UMP2/6‐31++G**, RCCSD(T)/aug‐cc‐pVDZ//UMP2/6‐31++G**, RCCSD(T)/aug‐cc‐pVTZ(spd,sp)//UMP2//6‐31++G**, RCCSD(T)/CBS//M05/6‐31+G**, and RCCSD(T)/CBS//UMP2/6‐31++G** MEPs, and associated gradients and Hessians, were used in reaction rate coefficient calculations based on the transition state theory (TST). Reaction rate coefficients were computed between 300 and 1500 K at various levels of TST, which include conventional TST, canonical variational TST (CVT) and improved CVT (ICVT), and with different tunneling corrections, namely, Wigner, zero‐curvature, and small‐curvature (SCT). The computed rate coefficients obtained at different ab initio, DFT and TST levels are compared with experimental values available in the 1000–1200 K temperature range. Based on the rate coefficients computed at the ICVT/SCT level, the highest TST level used in this study, the BH&HLYP functional performs best among all the functionals used, while the RCCSD(T)/CBS//MP2/6‐31++G** level is the best among all the ab initio levels used. Comparing computed reaction rate coefficients obtained at different levels of theory shows that, the computed barrier height has the strongest effect on the computed reaction rate coefficients as expected. Variational effects on the computed rate coefficients are found to be negligibly small. Although tunneling effects are relatively small at high temperatures (∼1500 K), SCT corrections are significant at low temperatures (∼300 K), and both barrier heights and the magnitudes of the imaginary frequencies affect SCT corrections. © 2012 Wiley Periodicals, Inc.

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Section: Discussionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Mok

Lee

et al. 2012

J Comput Chem

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“…The model 2 should be recommended for fitting since it gives very small fitting errors for the reactions studied in this work and other references. [50,51] To illustrate the discrepancy caused by fitted models, we plot the rate constants k 1 and k 2 fitted by the model 1 and model 2 in Figures 7a and 7b, respectively. Model 2 clearly provides a better low-temperature asymptotic behavior, which is very important to generate accurate rate constants at any temperature within the range that is used in the fitting and to extrapolate the rate constants beyond the temperature range that used in the fitting.…”

mentioning

confidence: 99%

Hydrogen abstraction reactions of OH radicals with CH₃CH₂CH₂Cl and CH₃CHClCH₃: A mechanistic and kinetic study

Wang

et al. 2011

J Comput Chem

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The hydrogen abstraction reactions of OH radicals with CH₃CH₂CH₂Cl and CH₃CHClCH₃ (R2) have been investigated theoretically by a dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points are calculated at the B3LYP/6-311G(d,p) level. To improve the reaction enthalpy and potential barrier of each reaction channel, the single point energy calculation is performed by the BMC-CCSD method. Using canonical variational transition-state theory (CVT) with the small-curvature tunneling correction, the rate constants are evaluated over a wide temperature range of 200-2000 K at the BMC-CCSD//B3LYP/6-311G(d,p) level. For the reaction channels with the negative barrier heights, the rate constants are calculated by using the CVT. The calculated total rate constants are consistent with available experimental data. The results show that at lower temperatures, the tunneling correction has an important contribution in the calculation of rate constants for all the reaction channels with the positive barrier heights, while the variational effect is found negligible for some reaction channels. For reactions OH radicals with CH₃CH₂CH₂Cl (R1) and CH₃CHClCH₃ (R2), the channels of H-abstraction from -CH₂ - and -CHCl groups are the major reaction channels, respectively, at lower temperatures. With temperature increasing, contributions from other channels should be taken into account. Finally, the total rate constants are fitted by two models, i.e., three-parameter and four-parameter expressions. The enthalpies of formation of the species CH₃CHClCH₂, CH₃CHCH₂Cl, and CH₃CH₂CH₂Cl are evaluated by isodesmic reactions.

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The Influence of Initial Defects on Impact Ignition of Aluminum/Polytetrafluoroethylene Reactive Material

Ren

Ning

et al. 2019

Adv Eng Mater

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Aluminum/polytetrafluoroethylene (Al/PTFE) reactive material is a typical multifunctional energetic material, which can release enormous energy under impact loading. To clarify its ignition mechanism, a Split Hopkinson pressure bar (SHPB) is used to conduct the impact ignition experiment on reactive materials with different initial defects. The experimental results show that the measured minimum specific incident energy that can cause the ignition for the specimen without pre‐impact (MSed specimen) increases slowly from 97.5 to 101 Jcm−2 with the molding pressure first, but drops substantially to 83.3 Jcm−2 as the molding pressure increases to 100 MPa. In addition, only the MSed specimens with the molding pressure above 100 MPa are ignited at the third stress pulse. Combined with the results of scanning electron microscopy, it is found that the existence of local larger pores inside the MSed specimens with high molding pressures (100, 120, and 150 MPa) contributes to the increase in damage level under impact and thus reduces the ignition threshold. The impact ignition experiment on the pre‐impacted specimens (MSed + PIed specimens) indicates that a phenomenon of damage sensitization exists in Al/PTFE reactive materials, confirming that the initial defects and damage evolution have significant effects on the impact ignition of the material.

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Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Cited by 7 publications

References 37 publications

Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Hydrogen abstraction reactions of OH radicals with CH₃CH₂CH₂Cl and CH₃CHClCH₃: A mechanistic and kinetic study

The Influence of Initial Defects on Impact Ignition of Aluminum/Polytetrafluoroethylene Reactive Material

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Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Cited by 7 publications

References 37 publications

Rate coefficients of the CF3CHFCF3 + H → CF3CFCF3 + H2 reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Rate coefficients of the CF3CHFCF3 + H → CF3CFCF3 + H2 reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Hydrogen abstraction reactions of OH radicals with CH3CH2CH2Cl and CH3CHClCH3: A mechanistic and kinetic study

The Influence of Initial Defects on Impact Ignition of Aluminum/Polytetrafluoroethylene Reactive Material

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Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Rate coefficients of the CF₃CHFCF₃ + H → CF₃CFCF₃ + H₂ reaction at different temperatures calculated by transition state theory with ab initio and DFT reaction paths

Hydrogen abstraction reactions of OH radicals with CH₃CH₂CH₂Cl and CH₃CHClCH₃: A mechanistic and kinetic study