Anomalous kinetics of the reaction between OH and HO₂on an accurate triplet state potential energy surface

Abstract

The quasi-classical trajectory predicts the rate coefficient of the OH + HO2 → H2O + O2 reaction based on a full dimensional accurate PIP-NN PES, which is fit to 108 000 points calculated at the CCSD(T)-F12a/AVTZ level.

Neural Network Potential Energy Surfaces for Small Molecules and Reactions

“…The PIP-NN method was used to produce the PES for the reaction OH + HO2 → H2O + O2 in Ref. 201 . The PES was fitted with a two-hidden later PIP-NN to 108,000 UCCSD(T) energies with an rmse of 12.6 meV (102 cm -1 ) and quasiclassical trajectory calculations performed on it.…”

“…62 to fit the potentials of C10H20, retinol and several other molecules. They showed, in particular, that the NN fitted to DFT can provide better structures and relative energies that semi-empirical methods like AM1, 207 PM6 208 or DFTB 201 . Gastegger and Marquetand applied a Behler type NN to fit the PES for an organic reaction, the Claisen rearrangement of allyl vinyl ether to 4-pentenal to DFT data with an accuracy of around 0.1 kcal/mol (35 cm -1 ).…”

Validating Experiment for the Reaction H2 + NH2- by Dynamical Computations on an Accurate Full-Dimensional Potential Energy Surface

“…As has been detailed in our previous work for PESs of various systems, [35][36][37][38][39][40][41][42][43][44] developing PESs consists of three procedures: sampling a set of points in dynamical relevant regions, calculating their energies, and fitting them. As mentioned above, for ion-neutral molecule reactions, long-range interaction exists between reactants or between products.…”

“…29 By introducing an adjusted temperature dependent term, Gianturco et al employed the variational transition state (VTST) approach to obtain temperature-dependent rate coefficients of R1 that are consistent with experiment over 300 ~ 8 K. 4 In order to further provide directly the reaction dynamical insights in R1, such as resonance, multidimensional tunneling, mode specificity effect, and stereodynamical effect, quantum dynamical simulations are required to carried out on a reliable full-dimensional potential energy surface (PES). 30 Thanks to advances in various neural network (NN)-based fitting methods, [31][32][33][34] reliable full-dimensional PESs for reactive systems with up to seven atoms [35][36][37][38][39][40][41][42][43][44] are available by fitting hundreds of thousands of configurations, whose energies were determined at the explicitly correlated CCSD(T) with the AVTZ basis set (CCSD(T)-F12a/AVTZ). 45,46 However, due to the long-range interactions between the negatively charged ions and the neutral molecules, 2 the PES for R1 should cover a huge configuration space, particularly in the reactant or product channels, making the construction of the full-dimensional accurate PES more challenging.…”

Validating Experiments for the Reaction H2 + NH2- by Dynamical Calculations on an Accurate Full-Dimensional Potential Energy Surface

“…or quantum dynamical (QD) calculations, a reliable full-dimensional potential energy surface (PES) is required. 31 Thanks to advances in various neural network (NN)-based fitting methods, [32][33][34][35] reliable full-dimensional PESs for reactive systems with up to seven atoms [36][37][38][39][40][41][42][43][44][45][46][47][48] are reported by fitting hundreds of thousands of configurations, whose energies were determined at the explicitly correlated CCSD(T) with the AVTZ basis set (CCSD(T)-F12a/AVTZ). 49,50 However, due to the long-range interactions between the negatively charged ions and the neutral molecules, 2 the PES of R1 covers a huge configuration space, particularly in the reactant or product channels, making the construction of the full-dimensional accurate PES more challenging.…”