Global dynamics and transition state theories: Comparative study of reaction rate constants for gas‐phase chemical reactions

Abstract

In this review article, we present a systematic comparison of the theoretical rate constants for a range of bimolecular reactions that are calculated by using three different classes of theoretical methods: quantum dynamics (QD), quasi-classical trajectory (QCT), and transition state theory (TST) approaches. The study shows that the difference of rate constants between TST results and those of the global dynamics methods (QD and QCT) are seen to be related to a number of factors including the number of degrees-of-freedom (DOF), the density of states at transition state (TS), etc. For reactions with more DOF and higher density of states at the TS, it is found that the rate constants from TST calculations are systematically higher than those obtained from global dynamics calculations, indicating large recrossing effect for these systems. The physical insight of this phenomenon is elucidated in the present review.

Quasi‐classical trajectory stereodynamics study of the Li + HF(v = 0, j = 0) → LiF + H reaction

“…Their study showed a very good agreement between the QCT and the previous quantum calculations [15]. Moreover, as revealed in previous studies [37,38], there exists qualitative agreement between QCT and quantum calculations for many reactive systems. Therefore, QCT method can provide reliable dynamical quantities in many cases and thus can be used here as an efficient tool for dynamics exploration.…”

A new specific mechanism for thioacid/azide amidation: electronic and solvent effects

“…Similarly, the rate equation can be deduced into a same functional form as the experiment observation (6) when Considering the above analysis, the TS2 step of the channel 1 has very low barrier and hence high rate (~ 10 11 s -1 ), while the protonation process is generally low barrier or no-barrier just judged from the usual observations in experiments and calculations [29,30]. Such low barrier protonation process of the bimolecular reaction belongs to diffusion-controlling reaction in various solvents (k d ≈ 10 9 -10 11 M -1 s -1 ) [30].…”

“…Such low barrier protonation process of the bimolecular reaction belongs to diffusion-controlling reaction in various solvents (k d ≈ 10 9 -10 11 M -1 s -1 ) [30]. Therefore, in low-viscosity solvents, the two channels may coexist, while in high-viscosity medium, the diffusionrate reduces greatly which results in the bimolecular protonation reaction can hardly compete with the monomolecular reaction of TS2 step in the channel 1.…”

Quasi-classical trajectory approach to the stereo-dynamics of the reaction F + HO → HF + O

“…[14,[16][17][18][19][20][21][22][23][24][26][27][28][29][30]. The classical Hamilton's equations are numerically integrated in three dimensions.…”