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An apparent failure of density functional theory (DFT) with the local density approximation (LDA) or generalized gradient approximations (GGA) is the overestimation of the electronic static dielectric constant compared to experiment. Since the dielectric constant is determined by the second derivative of the ground-state energy with respect to an applied electric field, it is a ground state property and can in principle be calculated exactly within DFT. However, for medium- and small-band-gap materials, the dielectric constant is overestimated by at least 10% in LDA-based calculations. A slight reduction occurs in the case of silicon using GGA rather than LDA. The discrepancy between experiment and LDA- or GGA-based calculations of the dielectric constant indicates a principal failure inherent to both approximations. This failure can be traced back to the neglect of the exchange-correlation energy's polarization dependence in LDA and GGA. The talk and the paper quantify the relevance of the neglect of polarization dependence for medium- and wide-gap semiconductors.

Talk on DPFT.

Paper on DPFT.

To cite this page:
Density Polarization Functional Theory
<http://www.physics.ohio-state.edu/~aulbur/dpft/dpft.html>