Current-density implementation for calculating flexoelectric coefficients

Flexoelectricity, where a voltage is induced in an insulator by a strain gradient, becomes increasingly important as electronic devices shrink to the nanoscale. In order to develop a quantitative understanding of the flexoelectric effect in materials, the authors have developed and implemented a first-principles methodology based on density functional perturbation theory to calculate the flexoelectric response. The strategy of mapping a strain gradient onto a long-wavelength acoustic phonon, and calculating the electrical response via the current density, allows the full flexoelectric tensor to be determined with unprecedented accuracy and efficiency. This paves the way for an improved understanding of the underlying mechanisms responsible for flexoelectric effects, thus promising improved control of these effects in the context of nanoelectronic devices.