Isigami: a Novel Highly Reconfigurable Surface*

Isolated disclinations in an asymptotically flat two-dimensional sheet create local regions of positive and negative Gaussian curvature whose mechanical inversion can form the basis for a reconfigurable surface with a wide range of distinct metastable shapes. Classical molecular dynamics of a graphene monolayer with equal numbers of 5-fold (conical) and 7-fold (saddle) rings arrayed in a kagome-like lattice elucidates this behavior. For a finite patch of this material, a complete enumeration of its shapes uncovers a near-Gaussian ``density of shapes'' and reveals the energy scale of interaction between nearby cones and saddles. A ~10 nm patch of such material can assume hundreds of distinct metastable conformations with tunable stability and topography on a length-scale similar to that of protein teritary structure. As every 5-fold disclination provides a distinct up/down Ising-like degree of freedom -- and these dominate the shape-changing behavior -- we call this means of controlling membrane shape through disclination reconfiguration Isigami.