Origin of simple staging in graphite intercalation compounds

We present a simple model of staging in graphite intercalation compounds. Unlike previous theoretical studies, finite-$T$ calculations based on our model yield the staged structures which are observed experimentally. Certain choices of model parameters result in more complex structures such as those predicted recently by Safran. The model provides physical guidelines for identifying materials in which the latter structures may be realized. Rich and varied phase diagrams are predicted.