Spin-density functional theory: Some open problems and application to inhomogeneous Heisenberg models

Authors

  • K. Capelle,

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    1. Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP Brazil
    • Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP Brazil
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  • Valter L. Líbero

    1. Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP Brazil
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Abstract

Spin-density functional theory (SDFT) is the most widely implemented and applied formulation of density functional theory. However, it is still finding novel applications, and occasionally encounters unexpected problems. In this article, we first briefly describe a few of the latter, related to issues such as nonuniqueness, noncollinearity, and currents. We then turn to an example of the former, namely SDFT for the Heisenberg model. It is shown that time-honored concepts of Coulomb DFT, such as the local-density approximation, can be applied to this (and other) model Hamiltonians, as well, once the concept of “density” has been suitably reinterpreted. Local-density-type approximations for the inhomogeneous Heisenberg model are constructed. Numerical applications to finite-size and impurity systems demonstrate that DFT is a computationally efficient and reasonably accurate alternative to conventional methods of statistical mechanics for the Heisenberg model. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

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