Colors code the magnitude of the gradient, with red corresponding to the largest values.
Unstable modes exist within the three interpenetrating planar slab regions. My group uses computational methods to understand and predict the properties of materials. At the most fundamental level, first-principles quantum mechanical methods using periodic boundary conditions are remarkably successful in describing the geometry, electronic and vibrational excitations that determine the properties of a material. For example, we recently reported the first calculation of the piezoelectric tensor in a ferroelectric material. First-principles methods are computationally intensive, however, and are limited in scope to simulations of less than about a hundred atoms.