Role of conformational structures and torsional anharmonicity in controlling chemical reaction rates and relative yields: butanal + HO₂reactions

Nanodusty plasma chemistry: a mechanistic and variational transition state theory study of the initial steps of silyl anion–silane and silylene anion–silane polymerization reactions

“…The MS-CVT/SCT rate constants for the forward reactions of steps 1-3 in R1 and R2 are fitted using recently proposed 41,42 multi-parameter fitting expressions. The MS-CVT/SCT rate constants for the forward reactions of steps 1-3 in R1 and R2 are fitted using recently proposed 41,42 multi-parameter fitting expressions.…”

Theoretical studies on mechanism and kinetics of the hydrogen-abstraction reaction of CF3C(O)OCH2CH3 with OH radicals

“…It is seen that calculated dual-level ICVT/ SCT rate constant at T = 298 K is 7.0 Â 10 À13 cm 3 molecule À1 s À1 , slightly higher than the experimental value of (2.64 AE 0.59) Â 10 À13 cm 3 molecule À1 s À1 [12]. It should be noted that as mentioned in the recent studies by Truhlar et al [21][22][23], ideally, for the case that the reactants and the transition states have multiple conformers, the multi-structural variational transition state theory (MS-VTST) approach is a convenient way to include contributions of all multiple structures and torsional anharmonicity and, hence, provides reliable thermal rate constants for the reaction. The conformational-rotational-vibrational partition functions can be calculated by the MSTor [24] program developed by Truhlar group, and the error due to neglecting the factors arising from multistructural anharmonicity has been discussed in Refs.…”

“…The conformational-rotational-vibrational partition functions can be calculated by the MSTor [24] program developed by Truhlar group, and the error due to neglecting the factors arising from multistructural anharmonicity has been discussed in Refs. [22,23]. In the present study, however, we did not consider the role of torsional anharmonicity but treated vibrations by a two-structure harmonic approximation, that is, the standard treatment in terms of a single structure of reactants and a single structure of the transition state.…”

Assessment of model chemistries for hydrofluoropolyethers: A DFT/M08‐HX benchmark study

“…By taking these factors into account we opted for an electronic structure method with low CPU time scaling, such as KS‐DFT (which in many cases scales approximately as K 4 , where K is a measure of the size of the molecule, typically related to the number of basis functions). Based on published research concerning the reactivity of a variety of volatile organic compounds and on our own preliminary calculations on HG‐ and ‐ , KS‐DFT (employing M06‐2X and M08‐HX functionals) and MP2 appear to be promising theoretical approaches. In the previously cited list of references M06‐2X is used extensively while M08‐HX is only used once, but because this functional is an improvement on M06‐2X, we opted to make it our benchmark functional in our calculations, which will also include a comparison between the two functionals.…”