MEP–MPE potential energy surface for the Cl + CH₄ → HCl + CH₃ reaction

Abstract

A potential energy functional based on a many-process expansion minimum energy path approach has been fitted to the ab initio potential energy values of the Cl ϩ CH 4 system. The functional form adopted, the parameters of the fitted surface, and the variation of the cone of acceptance as a function of relevant parameters are discussed.

Modeling the Kinetics of Bimolecular Reactions

“…Especially for interpolation, the distinction between these kinds of fits and interpolations is not, however, as clear-cut as it might first seem because in all methods the interpolation or fit is a stronger function of nearby data than far away data, and as the dependence on distance away becomes steeper, a method becomes more local. In recent years, the increasing accuracy of WFT calculations for small systems has been responsible for the appearance of many interpolation algorithms. − …”

“…This method was recently applied to the OH + HCl reaction . For systems with more than four atoms, García et al developed an approximate method based partly on the LAGROBO method and partly on the MBE method, which they applied to build the PES for the hydrogen abstraction reaction from methane by chlorine. Duin et al proposed an extension of molecular mechanics to reactive systems by using bond orders.…”

Configuration-Space Sampling in Potential Energy Surface Fitting: A Space-Reduced Bond-Order Grid Approach

“…This has called our attention to PES-channelrelated variables adapting the grids of BO points to auxiliary variables linked to minimum energy paths. 55,58,88 Moreover, the SRBO approach may be usefully combined with the previoulsy quoted approaches seeking PES refinement either via dynamical sampling with classical trajectories or through successive-degree fitting, as in the most recent scheme by the Dawes group. 34 Extensions of the SRBO approach to higher dimensionality problems with SRBO variables being employed for the breaking and forming bonds mixed with other internal coordinates are being pursued, while applications to compute for the first time the ground-state PES of the system C 2 H + to model the reactive process C + CH + → C 2 + + H of interest in interstellar chemistry will be soon published.…”

“…Then, specific features of reactive PESs such as wells or saddles are known to require specific attention, and a rectangular domain of the SRBO grid might be inappropriate. This has called our attention to PES-channel-related variables adapting the grids of BO points to auxiliary variables linked to minimum energy paths. ,, Moreover, the SRBO approach may be usefully combined with the previoulsy quoted approaches seeking PES refinement either via dynamical sampling with classical trajectories or through successive-degree fitting, as in the most recent scheme by the Dawes group …”

Collisional O2+ N2State-Selected Cross Sections for Open Science Cloud Reuse

“…These concepts are then applied in the paper to the MN PES to the end of modeling the energy dependence of the detailed cross sections computed on it for the O 2 + N 2 dissociative processes. The approach used for that purpose is the so-called many process expansion (MPE) BO representation in which the PES is formulated as a combination of process-specific BO channels connecting the reactants to the relevant products. − The coefficients of the combination allow a flexible switching among the process-specific terms while the formulation of the individual terms allows the accurate reproduction of local features.…”