Impact of Post-CCSD(T) Corrections on Reaction Energetics and Rate Constants of the OH^• + HCl Reaction

Abstract

High level ab initio calculations have been performed to predict the reaction energy and barrier height for the OH + HCl reaction. After including the effect of full quadratic excitations at the coupled cluster level, in addition to core, relativistic, spin-orbit, and diagonal Born-Oppenheimer corrections, we found the values of reaction energy and barrier height to be -15.29 and +2.38 kcal mol, respectively. Employing this reaction energy and barrier height, we used variational transition state theory in conjunction with small curvature tunneling to calculate the rate constants within a temperature range from 138 to 1000 K. The calculated rate constants were found to be in good agreement with available experimental results throughout the whole temperature range.

Effects of water, ammonia and formic acid on HO2 + Cl reactions under atmospheric conditions: competition between a stepwise route and one elementary step

“…Moreover, many previous studies have appeared in the literature on the electronic structure of the cluster H 2 O/Cl. 25,26 These situations have stimulated our interest in modeling the gas-phase reaction of the H 2 O/HO 2 / Cl ternary system, in which a single water molecule serves as a catalyst.…”

Effect of confinement on ammonia inversion

“…In controlling a chemical reaction, in addition to the reaction energy and reaction barrier, tunneling also plays an important role [30][31][32][33][34]. The signature of tunneling is evident in the behavior of the rate coefficients for certain hydrogen transfer reactions at low temperatures (at energies below the reaction barrier) [31,32]. Tunneling seems to be also important in certain organic reactions where heavy atoms like carbon, oxygen, sulfur and nitrogen are involved [35][36][37][38][39].…”

Nitrous acid (HONO) as a sink of the simplest Criegee intermediate in the atmosphere

“…1,6 The concentration of HONO in the Earth's atmosphere usually varies from 1.0 ppb to 9.7 ppb, [1][2][3]7 but in some areas, it can be as high as 20.0 ppb. 8 Although, the importance of HONO in tropospheric chemistry mainly comes from the fact that it produces OH by photo-dissociation, which is one of the most important oxidants present in the troposphere, [9][10][11][12][13] it is important to mention that HONO itself can also participate in various bimolecular reactions. 1 The bimolecular reactions of HONO with atmospheric co-reactants become more crucial in the nighttime as at night, due to the absence of photolysis, the concentration of HONO can become relatively high.…”