In the presence of ATP and Mg⁺², polypeptide complexes called chaperonins can aggregate into large-scale arrays of more than one kind. Two arrays with strikingly different symmetry, namely one-dimensional filaments and two-dimensional sheets, in fact form under very similar conditions, but rarely coexist. Professor Geissler and postdoc Steve Whitelam have developed a model for this self-assembly in order to learn how multiple structures can be programmed into a single solute. A chaperonin's roughly spherical crystal structure is shown in (a), along with the handful of geometric parameters we use to characterize inter-particle forces. Simple potential functions U, depending primarily on orientations relative to the inter-particle separation vector are sufficient to encourage assembly into filaments and sheets. These functions and corresponding configurations obtained from computer simulations are shown in (b) and (c). Further calculations will explore how external conditions determine kinetics of aggregation and discriminate between different structures. The ultimate aim of these studies is to predict chemical modifications of these molecules that will modulate structural and dynamical features in useful ways. Collaborative work with Professor Matt Francis, whose laboratory specializes in such modifications, aims to exploit such calculations as a practical basis for nano-scale material design.