Stinson, JL; Kathmann, SM; Ford, IJ; (2014) Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water. The Journal of Chemical Physics , 140 (2) , Article 024306. 10.1063/1.4860973.

Preview

Text Ford_pdf_archive_JCPSA6_vol_140_iss_2_024306_1.pdf Download (1MB) | Preview

Abstract

The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei, and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics method at the density functional level of theory. The general effect of zero-point motion is to distort the mean structure slightly, and to promote the extent of proton transfer with respect to classical behaviour. In a particular configuration of one sulphuric acid molecule with three waters, the range of positions explored by a proton between a sulphuric acid and a water molecule at 300 K (a broad range in contrast to the confinement suggested by geometry optimisation at 0 K) is clearly affected by the inclusion of zero point motion, and similar effects are observed for other configurations.

Download activity - last month

Export as JSONCSVXML

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item