Stengel, MassimilianoVanderbilt, David2010-11-302010-11-302010-11-30200910.1103/PhysRevB.80.241103https://infoscience.epfl.ch/handle/20.500.14299/59512WOS:000273229200003In the framework of the modern theory of polarization, we rigorously establish the microscopic nature of the electric displacement field D. In particular, we show that the longitudinal component of D is preserved at a coherent and insulating interface. To motivate and elucidate our derivation, we use the example of LAO/STO interfaces and superlattices, where the validity of the above conservation law is not immediately obvious. Our results generalize the "locality principle" of constrained-D density-functional theory to the first-principles modeling of charge-mismatched systems.Berry phasedensity functional theorydielectric polarisationelectric fieldsferroelectric materialslanthanum compoundsstrontium compoundssuperlatticesPolarizationtext::journal::journal article::research article