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Intrinsic uncertainty on ab initio phase diagram and compound formation energy calculations: BCC Mo–Fe as a test case

Authors

  • Ney Sodré,

    1. Departamento de Física dos Materiais e Mecânica, Instituto de Fìsica da Universidade de São Paulo, CP 66318, CEP 05315-970 São Paulo-SP, Brazil
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  • Joelson Cott Garcia,

    1. Laboratório de Microeletronica do Departamento de Engenharia de Sistemas Eletrônicos, Escola Politécnica, Universidade de São Paulo, CP 61548, CEP 05424-970 São Paulo-SP, Brazil
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  • Lucy Vitoria Credidio Assali,

    1. Departamento de Física dos Materiais e Mecânica, Instituto de Fìsica da Universidade de São Paulo, CP 66318, CEP 05315-970 São Paulo-SP, Brazil
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  • Pablo Guillermo Gonzales-Ormeño,

    1. Universidad Nacional Tecnológica del Cono Sur de Lima, Sector 3, Grupo 1A 03, Cercado, Villa El Salvador, Lima, Peru
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  • Peter Blaha,

    1. Institut für Materialchemie, Technische Universität Wien, Getreidemarkt 9/165-TC, 1060 Wien, Austria
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  • Helena Maria Petrilli,

    1. Departamento de Física dos Materiais e Mecânica, Instituto de Fìsica da Universidade de São Paulo, CP 66318, CEP 05315-970 São Paulo-SP, Brazil
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  • Cláudio Geraldo Schön

    Corresponding author
    1. Computational Materials Science Laboratory, Department of Metallurgical and Materials Engineering, Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes, 2463, CEP 05508-900 São Paulo-SP, Brazil
    • Phone: +55-11-30915726, Fax: +55-11-30915243
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Abstract

Ab initio electronic structure calculations, within the Kohn–Sham scheme of the density functional theory, are often considered reliable and a powerful tool to provide ground state information on intermetallic compounds. More recently, it has been used in multi-scale intermetallic phase diagram calculations with particular importance when experimental data is lacking. In spite of this recent success, they rely on basic choices of the computational solution of the complicated quantum mechanical problem. Therefore, the calculated phase diagrams may depend on these choices. Here, we concentrate on the influence of some methodological aspects of the ab initio calculations on the resulting phase diagram, for a given statistical mechanics approach. We use the Full Potential-Linear Augmented Plane Wave and the Projector Augmented Wave Methods to perform electronic structure calculations combined with the cluster variation method in the irregular tetrahedron approximation to calculate the BCC Mo–Fe phase diagram. It is shown that all calculated phase diagrams present similar qualitative features (an asymmetric miscibility gap), but quantitative variations are found depending on some of the basic assumptions adopted for the electronic structure calculations. Based on these results, a “natural” accuracy of the order of ± 1 kJ mol−1 can be estimated for ab initio compound formation energies.

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