Molecular mechanism of heterogeneous ice nucleation on potassium feldspar

TL;DR

This study uses machine-learning molecular dynamics to identify the most active K-feldspar surface for ice nucleation, revealing molecular mechanisms that influence atmospheric ice formation.

Contribution

It systematically investigates multiple K-feldspar surfaces, identifying the (110) surface as the most active for ice nucleation through molecular simulations.

Findings

(110) surface exposes interfacial water resembling cubic ice

Direct observation of cubic-ice clusters forming at the surface

Provides molecular-level explanation for atmospheric ice formation

Abstract

Mineral dust aerosols strongly influence Earth's climate by acting as ice-nucleating particles (INPs). Feldspar minerals, particularly K-feldspar, are recognized as dominant INPs, and a previous study attributed this behavior to (100) surfaces exposed at defects. Using machine-learning molecular dynamics simulations, we systematically investigate ice nucleation on multiple K-feldspar surfaces. We identify the (110) surface, exposed at defects such as steps, as the most active plane for ice formation. This surface uniquely structures interfacial water into an arrangement resembling that on the (110) surface of cubic ice, providing an optimal template for nucleation. Using advanced sampling, we directly observe the formation of clusters with cubic-ice structure and their orientation agrees with experiment. These results provide a molecular-level explanation of how ice forms in our planet's atmosphere.