Three proposed crystallographic models of the pyrophyllite edge were simulated using the CLAYFF forcefield.  All three models provided reasonable results, but the �optimal� model, with fewest forcefield reassignments and the least surface energy bias as compared to ab initio optimizations of the pyrophyllite edge, can also be generalized to describe all relevant 2:1 phyllosilicate edge faces.  Molecular dynamics simulations with this optimal model can account for both a well-crystallized pyrophyllite particle and the disordered edges of 2:1 phyllosilicates, while resuscitating a long-standing (and nearly-forgotten) controversy over the crystal structures of smectite minerals.  Simulating Na+, Ca2+, and Cs+ adsorbed on the pyrophyllite edge-water interface at acidic to circumneutral pH identified inner-sphere binding sites associated with the aluminol groups of edge octahedra.

Molecular models of 2:1 phyllosilicate edges

243rd National Meeting (2012)

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