Accurate electronic free energies of the 3d,4d, and 5d transition metals at high temperatures

Xi Zhang, Blazej Grabowski, Christoph Freysoldt, Fritz Kormann, Jörg Neugebauer

Research output: Contribution to journalArticleScientificpeer-review

35 Citations (Scopus)
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Abstract

Free energies of bulk materials are nowadays routinely computed by density functional theory. In particular for metals, electronic excitations can significantly contribute to the free energy. For an ideal static lattice, this contribution can be obtained at low computational cost, e.g., from the electronic density of states derived at T=0 K or by utilizing the Sommerfeld approximation. The error introduced by these approximations at elevated temperatures is rarely known. The error arising from the ideal lattice approximation is likewise unexplored but computationally much more challenging to overcome. In order to shed light on these issues we have computed the electronic free energies for all 3d,4d, and 5d transition elements on the ideal lattices of the bcc, fcc, and hcp structures using finite-temperature density-functional theory. For a subset of elements we have explored the impact of explicit thermal vibrations on the electronic free energies by using ab initio molecular dynamics simulations. We provide an analysis of the observed chemical trends in terms of the electronic density of states and the canonical d band model and quantify the errors in the approximate methods. The electronic contribution to the heat capacities and the corresponding errors due to the different approximations are studied as well.

Original languageEnglish
Article number165126
Number of pages13
JournalPhysical Review B (Condensed Matter and Materials Physics)
Volume95
Issue number16
DOIs
Publication statusPublished - 2017

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