Transition state theory (TST) 1 is the most widely used theory for calculating rates of bimolecular eactions occurring in the gas phase and in condensed phases. TST is also incorporated into the widely used RRKM theory for unimolecular reactions. The popularity of TST is largely due to its simplicity and its usefulness for correlating trends in reaction rates in terms of easily interpreted quan...

A large set of quasi-classical, direct dynamics trajectory simulations were performed for decomposition of 1,5-dinitrobiuret (DNB) over a temperature range from 4000 to 6000 K, aimed at providing insight into DNB decomposition mechanisms. The trajectories revealed various decomposition paths and reproduced the products (including HNCO, N(2)O, NO(2), NO, and water) observed in DNB pyrolysis expe...

A classical theory is proposed to describe the non-RRKM effects in activated asymmetric top triatomic molecules observed numerically in classical molecular dynamics simulations of ozone. The Coriolis coupling is shown to result in an effective diffusive energy exchange between the rotational and vibrational degrees of freedom. A stochastic differential equation is obtained for the K-component o...

Statistical adiabatic channel model/classical trajectory (SACM/CT) calculations have been performed for transitional mode dynamics in the simple bond fission reactions of C(6)H(6)(+) --> C(6)H(5)(+) + H and n-C(6)H(5)C(4)H(9)(+) --> C(7)H(7)(+) + n-C(3)H(7). Reduced-dimensionality model potentials have been designed that take advantage of ab initio results as far as available. Average anisotrop...

The potential-energy surface for has been computed at the HF/6-311G** and MP2/6-311G** levels. The calculated H É 2 results conÐrm that trans-planar HOSO is a transition state but not a stable structure. The decomposition channel for the HOSO adduct has been studied by analysing the transition states and stationary points. The kinetic stimulus for the rearrangement and dissociation of the radic...

The rate constant for the NCN + NO 2 reaction has been measured by a laser photolysis/laser-induced fluorescence technique in the temperature range of 260-296 K at pressures between 100 and 500 Torr with He and N 2 as buffer gases. The NCN radical was produced from the photolysis of NCN 3 at 193 nm and monitored by laser-induced fluorescence with a dye laser at 329.01 nm. The rate constant was ...

The methyl (•CH3) + 3O2 radical is an important reaction in both atmospheric and combustion processes. We investigated potential energy surfaces for the effect of CO2 H2O molecules on a •CH3+ O2 system. mechanism three systems, i.e., •CH3 3O2, (+CO2) (+H2O), were explored using ab initio/DFT methods [CCSD(T)//M062X/6-311++G(3df,3pd)] combination with Rice−Ramsperger−Kassel−Marcus (RRKM)/master-...

Expressions are given for a solvent dynamics-modified Rice–Ramsperger–Kassel–Marcus ~RRKM! theory for clusters. The role of vibrational assistance across the transition state region is included. The usual differential equation for motion along the slow coordinate X in constant temperature systems is modified so as to apply to microcanonical systems. A negative entropy term, 2Sv(X), replaces the...