title: Accurate rates of the complex mechanisms for growth and dissolution of minerals using a combination of rare-event theories.
abstract: Mineral growth and dissolution are often treated as occurring via a single reversible process that governs the rate of reaction. We show that multiple distinct intermediate states can occur during both growth and dissolution. Specifically, we used metadynamics, a method for efficiently exploring the free-energy landscape of a system, coupled to umbrella sampling and reactive flux calculations to examine the mechanism and rates of attachment and detachment of a barium ion onto a stepped barite (BaSO(4)) surface. The activation energies calculated for the rate-limiting reactions, which are different for attachment and detachment, precisely match those measured experimentally during both growth and dissolution. These results can potentially explain anomalous non-steady-state mineral reaction rates observed experimentally and will enable the design of more efficient growth inhibitors and facilitate an understanding of the effect of impurities.
authors: Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS-6110, Oak Ridge, Tennessee 37831, USA. stackag@ornl.gov
authors: Andrew G
authors: AG
authors: Stack
authors: Paolo
authors: P
authors: Raiteri
authors: Julian D
authors: JD
authors: Gale