Erik Storm

SLU Festival of Science 2001 Oral Presentation

Molecular Modeling of Calcium Montmorillonite
via a Silicon Graphics O₂ Workstation

Through the use of Monte Carlo computer simulation, we investigated the effect of water content on calcium montmorillonite stability. Water contents varying from 0 to XX mg water per g clay.  We found three water contents, corresponding to 1-3 layers of water, at which the systems were noticeably more stable than others.  One layer of water is approximately 32 molecules per sheet of clay (8 unit cells).   Another goal of the research was to determine hydration number of calcium in these systems.  At the present time in this research, solvation shells varying between 6 and 8 waters have been seen. At higher water contents where behavior is closer to bulk water, solvation shells are seen to contain 8 water molecules, which is consistent with studies of aqueous calcium ions.  Larger calcium hydration numbers lead to a more stable system with more hydrogen bonding between solvating waters and the clay surface.