American Chemical Society
ja407286t_si_005.mpg (12.36 MB)

First-Principles Molecular Dynamics Simulation of Atmospherically Relevant Anion Solvation in Supercooled Water Droplet

Download (12.36 MB)
posted on 2013-10-16, 00:00 authored by Yu Zhao, Hui Li, Xiao Cheng Zeng
We present a comprehensive first-principles Born–Oppenheimer molecular dynamics (BOMD) simulation study of halide anion solvation in a deeply supercooled water droplet (with diameter ∼1.8 nm). We show that larger halide anions Br and I show “outer-layer surface preference”, whereas F exhibits bulk preference. Contrary to behavior of other halide anions, Cl in the water droplet appears to exhibit no strong tendency of surface or bulk preference at either the supercooled or ambient condition, a phenomenon not previously reported in the literature. BOMD simulation indicates that fully hydrated complex of F is mainly five-fold coordinated (showing square pyramid structure), whereas Cl, Br and I hydrated complexes are either five- or six-fold coordinated (showing sandwich-like structure). Among Cl, Br and I anions, BOMD simulation indicates that I exhibits the largest diffusion coefficient despite its largest size. However, computed resident time of the four halide ions suggests that Br can approach from the interior to the surface of the water droplet at a much faster rate than I and Cl.