Computational Approaches to Nanomineralogy

Nanomineralogy is concerned with the behavior of minerals on length scales between 10 A and 1 micron. Within the realm of computational science, molecular modeling methods have been working at the lower end of this scale for more than 50 years and comprise a relatively mature field even within the geosciences community (see Cygan and Kubicki 2001). Somewhere near the upper end of this scale, continuum approaches using bulk thermodyamics and homogeneous transport properties (diffusion, viscous flow and heat flow, and elastic moduli) can be used effectively (Turcotte and Schubert 1982). From one perspective, the nanoscale regime is the theoretical/ computational no-man’s land between atomistic and continuum scales, in which atoms cannot quite be ignored and continuum models cannot quite be applied. More generally, it is the simultaneous consideration of multiple scales, each requiring different methods, which, from the computational point of view, provides the driving force and makes this field exciting. The focus of this volume is on nanoscale phenomena in mineralogy and geochemistry in low-temperature, near-surface environments. This is indeed a rich area for multiscale investigations, as shown in Figure 1⇓. At the finest scales, one is interested in the spatio-temporal variability of the collective wave functions (or density) of electrons. At a simple level, this results in the formation of chemical bonds. Even at this scale, consideration of the detailed aspects of electron density topology is an emerging area (Bader 1990; Gibbs et al. 1998; Rescigno et al. 1999; Blanco et al. 2000; Espinosa and Molins 2000). As more than a few atoms begin to interact, complexity begins to be revealed in molecular arrangements as well as the electronic structure. In mineralogy, we have polynuclear clusters (such as discussed in detail by Casey and Furrer in this volume) and nanoporous minerals, …