Reaction Dynamics of NO⁺ with Water Clusters

Abstract

The reaction of NO+ with water molecules plays a crucial role in the D-region of the atmosphere because the reaction provides nitrous acid (HONO) and protonated water species (H3O+). In this study, the reaction of NO+ with water clusters, NO+ + (H2O) n (n = 1–7), was investigated by means of the direct ab initio molecular dynamics method to elucidate the reaction mechanism of NO+ in the atmosphere from a theoretical viewpoint. At n = 1 and 2, the reaction of NO+ with (H2O) n led to the formation of a complex: NO+ + (H2O) n → NO+(H2O) n (n = 1 and 2). At n = 3, the formation channel of HONO was open, and HONO was formed according to NO+ + (H2O) n → HONO---H+(H2O) n–1 (n = 3), through which H3O+ was also formed as H+(H2O)2. However, the HONO formation efficiency was significantly low for n = 3. In large clusters with n = 4–7, the HONO formation channel became the main channel, and the dissociation of HONO from the HONO--H+(H2O) n−1 complex occurred in part: NO+ + (H2O) n → HONO---H+(H2O) n−1 → HONO + H+(H2O) n−1. The energetics and reaction mechanism were discussed on the basis of theoretical results.

Formation Mechanism of Odd- and Even-Numbered Hydrogen Cluster Cations Using the Direct Ab Initio Molecular Dynamics Approach

“…The deviation in the total energy was less than 0.01 kcal/mol. The effects of ZPE on the reaction mechanism were investigated using the classical vibrational sampling method (microcanonical ensemble). − Direct AIMD calculations were carried out using our code. − …”

“…The reactions are as follows ( H 2 ) n + normalh normalv → false[ ( H 2 ) n + ] normalv normale normalr , .25em normali normalo normaln normali normalz normala normalt normali normalo normaln false[ ( H 2 ) n + ] normalv normale normalr → normalp normalr normalo normald normalu normalc normalt ( P D ) where [(H 2 ) n + ] ver is the vertical ionization state of the (H 2 ) n cluster. The direct ab initio molecular dynamics (AIMD) method − was applied in reaction (5).…”

“…The reactions are as follows where [(H 2 ) n + ] ver is the vertical ionization state of the (H 2 ) n cluster. The direct ab initio molecular dynamics (AIMD) method − was applied in reaction (5).…”

Intracluster Reaction Dynamics of Ionized Micro-Hydrated Hydrogen Peroxide (H2O2): A Direct Ab Initio Molecular Dynamics Study

“…The effects of ZPE on the reaction mechanism were investigated using the classical vibrational sampling method (microcanonical ensemble). − The effects of the functional on the reaction mechanism were investigated using the ωB97XD functional and compared with those obtained with the CAM-B3LYP functional. Direct AIMD calculations were carried out using our own code. − …”

“…In the present study, the reactions of ionized hydrogen peroxide–water clusters, denoted as [H 2 O 2 –(H 2 O) n ] + , after vertical ionization of neutral cluster, are investigated using the direct ab initio molecular dynamics (MD) method − to elucidate the effects of micro-solvation on the reaction of H 2 O 2 . Clusters with one to five water molecules, H 2 O 2 –(H 2 O) n ( n = 1–5), are examined.…”