The binary H2SO4-H2O nucleation is considered to be an important pathway for the formation of secondary aerosols in the atmosphere. We investigate the thermodynamics of sulfuric acid hydration using ab initio quantum mechanical methods. For H2SO4(H2O)n, (H2SO4)2(H2O)n,  HSO4-(H2O)n, and SO42-(H2O)n  where n = 1-6, we use a scheme combining molecular dynamics configurational sampling with high-level ab initio calculations to locate the global and many low lying local minima for each cluster size.  From the Boltzmann averaged Gibbs free energies, we derive important conclusions about acid dissociation in small clusters, the stability of neutral and ionic species and the abundance of small sulfuric acid hydrates under atmospheric conditions. The implications of our findings for different nucleation mechanisms leading to aerosol formation will be discussed.

Quantum mechanical study of sulfuric acid hydration and its atmospheric implications

244th National Meeting (2012)

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