Computational Quantum Chemistry: A New Approach to Atmospheric Nucleation

Abstract A clear understanding of the nucleation and particle formation mechanisms is critically important for assessing the lifecycle of atmospheric particles and predicting the climate changes associated with aerosol radiative forcing. The main assumption of the liquid droplet approach used in the classical nucleation theory is that the properties of nucleating and pre-nucleation clusters are the same as those of the bulk liquid. However, molecular clusters formed during the first few nucleation steps are quantum-mechanical systems, and cannot be adequately treated using the capillarity approximation and/or empirical potentials parameterized to the bulk liquid. This Review discusses the recent developments of theoretical methods to solve problems in the atmospheric nucleation theory, and is primarily focused on the quantum chemistry of common atmospheric nucleation precursors. The importance of the quantum-mechanical treatment of molecular clusters underlying nucleation will be outlined and future developments towards the “first principles” nucleation theory will be discussed.