Toward a Holistic Understanding of the Formation and Growth of Atmospheric Molecular Clusters: A Quantum Machine Learning Perspective

Abstract

The formation of atmospheric molecular clusters is an important stage in forming new particles in the atmosphere. Despite being a highly focused research area, the exact chemical species involved in the initial steps in new particle formation remain elusive. In this Perspective the main challenges and recent progression in the field are outlined with a special emphasis on the chemical complexity of the puzzle and prospect of modeling larger clusters. In general, there is a high demand for accurate and more complete quantum chemical data sets that can be applied in cluster distribution dynamics models and coupled to atmospheric chemical transport models. A view on how the community could reach this goal by applying data-driven machine learning approaches for more efficient exploration of cluster configurations is presented. A path toward larger clusters and direct molecular dynamics simulations of cluster formation and growth using machine learning models is discussed.

Ozone Initiates Human-Derived Emission of Nanocluster Aerosols

“…Amines, although present at concentrations several orders of magnitude lower than NH 3 , may also play a role. ,, Emissions of NCAs in several size bins were significantly positively correlated with glycine (C 2 H 5 NO 2 ), succinimide (C 4 H 5 NO 2 ), and cyclohexyl-prop-2-ynyl-amine (C 9 H 15 N, Table S3). Such a chemical process involving acids and NH 3 /amines has been identified as an important pathway to form atmospheric clusters. , …”

“…Such a chemical process involving acids and NH 3 /amines has been identified as an important pathway to form atmospheric clusters. 59,60 The concentration of nitric oxide (NO) was expected to be low during these chamber experiments, especially when ozone was present. Under such conditions the lifetimes of alkylperoxy radicals (RO 2 •), derived from ozone-initiated chemistry, are relatively long and autoxidation reactions can generate highly oxidized multifunctional compounds (HOMs).…”

“…63 Autoxidation reactions and consequent HOMs are still another potential contributor to the formation of NCA observed in the present study, as has been found in the atmosphere. 60 The aforementioned chemistry is associated most closely with aerosols of the smallest size…”

Clusteromics III: Acid Synergy in Sulfuric Acid–Methanesulfonic Acid–Base Cluster Formation

“…Studying acid–base clusters using quantum chemical methods is extremely time-consuming. We recently introduced the clusteromics approach, 46 which involves the comprehensive screening of small multicomponent molecular clusters, thereby providing direct insight into which chemical species are potentially involved in the initial cluster formation and growth. While giving insight into the species involved in cluster formation, the clusteromics approach also aids in constructing high-quality thermochemical data sets that can be applied to train quantum machine learning (QML) models.…”

Clusteromics II: Methanesulfonic Acid–Base Cluster Formation

“…Clusteromics provides guidance on which cluster systems are relevant for extending to larger sizes and yield a systematic approach for constructing thermochemical databases that can be applied to develop Quantum Machine Learning (QML) models. For further information on the clusteromics approach, we refer to our recent perspective …”