Nonconvex interactions and the occurrence of modulated phases

Abstract
Nonconvex interparticle interactions are proposed as a mechanism for the occurrence of modulated order in condensed matter. This is examined by application of a recent numerical algorithm to two microscopic models in which frustration is present only if the interparticle interactions are nonconvex. A devil’s staircase is found when the particles, in the ground state, make use only of the convex part of the interaction potential, whereas both first- and second-order transitions are found when the region of nonconvexity is felt by some of the particles.