The interaction of HCl with the (0001) face of hexagonal ice studied theoretically via Car-Parrinello molecular dynamics

The depletion of stratospheric ozone at high latitudes is caused by gas-pha se catalytic cycles involving active chlorine compounds produced through he terogeneous chemical reactions involving HCl. In this Letter, results aimed at understanding the activation of chlorine on ice cloud particle surfaces are presented. We focus specifically on HCl interacting with the ice surfa ce prior to reaction. We conclude that, in regions with a low surface densi ty of dangling OH groups, HCl may be either ionically or molecularly adsorb ed, but in regions with a high surface density of dangling OH groups, HCl i s ionically adsorbed. (C) 2001 Elsevier Science B.V. All rights reserved.