Convergent ab initio analysis of the multi-channel HOBr + H reaction

Ian T Beck; Mitchell E Lahm; Gary E Douberly; Henry F Schaefer 3rd

doi:10.1063/5.0200276

Convergent ab initio analysis of the multi-channel HOBr + H reaction

J Chem Phys. 2024 Mar 28;160(12):124304. doi: 10.1063/5.0200276.

Authors

Ian T Beck¹, Mitchell E Lahm¹, Gary E Douberly¹, Henry F Schaefer 3rd¹

Affiliation

¹ Department of Chemistry and Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA.

PMID: 38516979
DOI: 10.1063/5.0200276

Abstract

High-level potential energy surfaces for three reactions of hypobromous acid with atomic hydrogen were computed at the CCSDTQ/CBS//CCSDT(Q)/complete basis set level of theory. Focal point analysis was utilized to extrapolate energies and gradients for energetics and optimizations, respectively. The H attack at Br and subsequent Br-O cleavage were found to proceed barrierlessly. The slightly submerged transition state lies -0.2 kcal mol-1 lower in energy than the reactants and produces OH and HBr. The two other studied reaction paths are the radical substitution to produce H2O and Br with a 4.0 kcal mol-1 barrier and the abstraction at hydrogen to produce BrO and H2 with an 11.2 kcal mol-1 barrier. The final product energies lie -37.2, -67.9, and -7.3 kcal mol-1 lower in energy than reactants, HOBr + H, for the sets of products OH + HBr, H2O + Br, and H2 + BrO, respectively. Additive corrections computed for the final energetics, particularly the zero-point vibrational energies and spin-orbit corrections, significantly impacted the final stationary point energies, with corrections up to 6.2 kcal mol-1.