Dipole Interactions in Nanosystems

The dipole-dipole interaction influences nanoscopic matter by fixing the patterns of permanent, displacive, and induced dipole moments, subject to constraints of molecular size and other short range interactions. Prediction of these arrangements is a challenging problem. The eigenvector of maximum eigenvalue of the dipole-dipole interaction matrix can provide insights and sometimes a complete solution. As an example, the octahedral tilt instabilities of perovskite-type crystals is shown to optimize dipolar interactions. Therefore this instability can be designated as antiferroelectric, because dipole-dipole interactions are a dominant driving force.