Piezoelectrics are dielectric materials which convert electrical energy to mechanical energy (and vice-versa).  It is this coupling which makes them crucial to the success of a variety of modern devices including SONAR, ultrasound machines, non-volatile memory devices, and chemical and biological sensors.  Given their importance, there has been much research devoted to enhancing the electromechanical responses of these materials.  Recent advances in theory, most notably the ability to accurately compute the macroscopic polarization using first principles density functional theory, have opened the door to the computational discovery of new piezeoelectrics.  In this presentation, I will demonstrate how concepts and insights gained from first principles calculations can be used to tailor the properties of complex oxides.  In particular, I will discuss our use of epitaxial strain through superlattice geometries [1] and chemical composition and ordering [2] to predict structures with enhanced piezoelectric properties. 
1.  V. R. Cooper and K. M. Rabe, Phys. Rev. B 79 (18), 180101 (2009).
2.  S. Takagi, A. Subedi, D. J. Singh and V. R. Cooper, Phys. Rev. B 81 (13), 134106 (2010).