Theory of structural response to macroscopic electric fields in ferroelectric systems

Na Sai, Karin M. Rabe, and David Vanderbilt
Phys. Rev. B 66, 104108 – Published 30 September 2002
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Abstract

We have developed and implemented a formalism for computing the structural response of a periodic insulating system to a homogeneous static electric field within density-functional perturbation theory (DFPT). We consider the thermodynamic potentials E(R,η,E) and F(R,η,P), whose minimization with respect to the internal structural parameters R and unit cell strain η yields the equilibrium structure at fixed electric field E and polarization P, respectively. First-order expansion of E(R,η,E) in E leads to a useful approximation in which R(P) and η(P) can be obtained by simply minimizing the zero-field internal energy with respect to structural coordinates subject to the constraint of a fixed spontaneous polarization P. To facilitate this minimization, we formulate a modified DFPT scheme such that the computed derivatives of the polarization are consistent with the discretized form of the Berry-phase expression. We then describe the application of this approach to several problems associated with bulk and short-period superlattice structures of ferroelectric materials such as BaTiO3 and PbTiO3. These include the effects of compositionally broken inversion symmetry, the equilibrium structure for high values of polarization, field-induced structural phase transitions, and the lattice contributions to the linear and the nonlinear dielectric constants.

  • Received 18 May 2002

DOI:https://doi.org/10.1103/PhysRevB.66.104108

©2002 American Physical Society

Authors & Affiliations

Na Sai, Karin M. Rabe, and David Vanderbilt

  • Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019

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Issue

Vol. 66, Iss. 10 — 1 September 2002

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