Density functional theory description of random Cu-Au alloys

L.-Y. Tian, H. Levämäki, M. Kuisma, K. Kokko, Á. Nagy, and L. Vitos

Phys. Rev. B 99, 064202 – Published 19 February 2019

Abstract

Density functional alloy theory is used to accurately describe the three core effects controlling the thermodynamics of random Cu-Au alloys. These three core effects are exchange correlation (XC), local lattice relaxations (LLRs), and short-range order (SRO). Within the real-space grid-based projector augmented-wave (GPAW) method based on density functional theory (DFT), we adopt the quasinonuniform XC approximation (QNA), and take into account the LLR and the SRO effects. Our approach allows us to study the importance of all three core effects in a unified way within one DFT code. The results demonstrate the importance of the LLR term and show that going from the classical gradient level approximations to QNA leads to accurate formation energies at various degrees of ordering. The order-disorder transition temperatures for the 25%, 50%, and 75% alloys reach quantitative agreement with the experimental values only when also the SRO effects are considered.

Received 19 October 2018
Revised 22 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.064202

Physics Subject Headings (PhySH)

Electronic structure First-principles calculations

Disordered alloys Metals

Density functional calculations Density functional theory

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

L.-Y. Tian¹, H. Levämäki^1,*, M. Kuisma², K. Kokko^3,4, Á. Nagy⁵, and L. Vitos^1,6,7

¹Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
²Department of Chemistry, University of Jyväskylä, FIN-40014 Jyväskylä, Finland
³Department of Physics and Astronomy, University of Turku, FIN-20014 Turku, Finland
⁴Turku University Centre for Materials and Surfaces (MatSurf), FIN-20014 Turku, Finland
⁵Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen, Hungary
⁶Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75121 Uppsala, Sweden
⁷Research Institute for Solid State Physics and Optics, Wigner Research Center for Physics, P.O. Box 49, H-1525 Budapest, Hungary

^*levamaki@kth.se

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Vol. 99, Iss. 6 — 1 February 2019

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