title: Polarization and adiabatic pumping in inhomogeneous crystals.
abstract: We develop a general theory of electric polarization in crystals with inhomogeneous order. We show that the inhomogeneity-induced polarization can be classified into two parts: a perturbative contribution stemming from a correction to the basis functions and a topological contribution described in terms of the Chern-Simons form of the Berry gauge fields. The latter is determined up to an uncertainty quantum, which is the second Chern number in appropriate units. Our theory provides an exhaustive link between microscopic models and the macroscopic polarization.
authors.affiliation: Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA. xiaod@ornl.gov
authors.forename: Di
authors.initials: D
authors.lastname: Xiao
authors.forename: Junren
authors.initials: J
authors.lastname: Shi
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Clougherty
authors.forename: Qian
authors.initials: Q
authors.lastname: Niu