Silicates pyroxenoid

Atomistic simulations have also been performed on pyroxenes and pyroxenoids by Catlow et al. (1982) and predict the stable Mg end member to have the diopside structure and the stable Ca end member the wol-lastonite structure, as observed. However, only pair potentials were employed in this study, and Post and Burnham (1986) have found that diopside structures are poorly described within such a model. It would clearly be of interest to repeat the simulations using the three-body silicate potentials, which have yielded accurate Si-O-Si angles in quartz (Catlow et al., 1985). 

The pyroxenoid family of silicates (MSiOs, where M can be Mg " ", Ca , Fe " ", Mn , or mixtures thereof) illustrate this point. Good progress has also been made theoretically in using the Ising model or the anisotropic nearest-neighbor Ising (ANNI) model to interpret polytypism. 

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