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    Smearing scheme for finite-temperature electronic-structure calculations

    Matthieu Verstraete* and Xavier Gonze

    • Unité de Physico-Chimie et de Physique des Matériaux (PCPM), Université Catholique de Louvain, 1 Croix du Sud, B-1348 Louvain-la-Neuve, Belgium
    • *Electronic address: verstraete@pcpm.ucl.ac.be

    Phys. Rev. B 65, 035111 – Published 26 December, 2001

    DOI: https://doi.org/10.1103/PhysRevB.65.035111

    Abstract

    The use of energy-dependent occupation numbers in density-functional theory has two purposes: simulating the canonical ensemble for the electrons at nonzero temperature (Fermi-Dirac occupation numbers), and improving the convergence with respect to the number of electronic wave vectors sampling the Brillouin zone. We present a scheme which combines both, providing finite-temperature eigenstate occupations with an additional smearing to improve sampling convergence. After developing the formalism and extracting a correction formula for the free energy, we test them on a small system of metallic aluminum for temperatures under 3000 K. In this regime, the Fermi-Dirac smearing alone gives only a modest reduction in the number of wave vectors needed for convergence. Our scheme reduces significantly the number of wave vectors, while preserving the correct physical temperature dependence.

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