NER: Multiscale Modeling and Simulation of the Surface Nanolayer of Molecular Crystals

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 02-148, category NER. This study is aimed at modeling crystal morphology. Currently available methods to predict crystal morphology are unable to consider factors such as solvent composition, additives, and temperature variations; the prediction of polymorphs is even more challenging. Difficulties may be attributable to the fact that the information about surface structures is difficult to obtain, especially when a surface is submerged under another medium. As a result the importance of surface reconstruction may not be realized. The electronic structure of the nanolayer of crystal surfaces will be investigated to determine how the surface reconstruction affects crystal growth with multiscale modeling. At the atomic scale, quantum mechanics and density functional theory will be utilized to compute the surface structure when solvent and additive molecules are introduced to the surface. Based on the reconstructed surface at the molecular level, kinetic Monte Carlo will be employed to study the kinetics of individual molecular events such as surface diffusion, detachment, and adsorption. In terms of the broader impacts, this work will shed light on using the surface structure control for nanofabrication. The educational component will be the normal mentoring of graduate students.