Coherent potential approximation

About: Coherent potential approximation is a research topic. Over the lifetime, 1930 publications have been published within this topic receiving 36805 citations.

A Review of Solid-Solution Models of High-Entropy Alloys Based on Ab Initio Calculations

Abstract: Similar to the importance of XRD in experiments, ab initio calculations, as a powerful tool, have been applied to predict the new potential materials and investigate the intrinsic properties of materials in theory. As a typical solid-solution material, the large degree of uncertainty of high-entropy alloys (HEAs) results in the difficulty of ab initio calculations application to HEAs. The present review focuses on the available ab initio based solid-solution models (virtual lattice approximation, coherent potential approximation, special quasi-random structure, similar local atomic environment, maximum-entropy method, and hybrid Monte Carlo/molecular dynamics) and their applications and limits in single phase HEAs.

Theoretical Prediction of Curie Temperature in (Zn,Cr)S, (Zn,Cr)Se and (Zn,Cr)Te by First Principles Calculations

Abstract: The electronic structure and the magnetic properties of (Zn,Cr)S, (Zn,Cr)Se and (Zn,Cr)Te are calculated by using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation (KKR-CPA) within the local density approximation. Curie temperatures are calculated by the mean field approximation (MFA) and by Monte Carlo simulation. It is found that the MFA strongly overestimates the Curie temperatures for low concentrations due to shortrangeness of interactions in (Zn,Cr)S, (Zn,Cr)Se and (Zn,Cr)Te. The Curie temperatures of (Zn,Cr)Te calculated by Monte Carlo simulation agree very well with recent experimental values.

Ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys

Abstract: We have studied the ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys at the stoichiometric 1/4, 1/2, and 3/4 compositions in the framework of the multisublattice single-site (SS) coherent potential approximation (CPA). Charge-transfer effects in the random and the partially ordered alloys are included in the screened impurity model. The prefactor in the Madelung energy is determined by the requirement that the total energy obtained in direct SS CPA calculations should equal the total energy given by the Connolly-Williams expansion based on Green's function calculations for the ordered alloys that do not rely on the single-site approximation. We find that the prefactor to a large degree is independent of a lattice constant, concentration, and a long-range-order parameter and may be considered constant for a given alloy system. The calculated heats of formation for the ordered alloys are in good agreement with experimental data. For all the alloys the calculated ordering energy and the equilibrium lattices parameters are found to be almost exact quadratic functions of the long-range-order parameter.

Relationship between magnetocrystalline anisotropy and orbital magnetic moment in L1 0-type ordered and disordered alloys

Abstract: The magnetocrystalline anisotropy energy and orbital magnetic moment in L 1 0 -type transition metal alloys such as FePt, FePd, FeNi, CoPt, CoPd, and MnAl are evaluated while continuously varying the degree of order. The electronic structure with spin–orbit interaction is calculated by employing the tight-binding linear muffin-tin orbital method based on the local spin-density approximation. To control the degree of order, we consider a substitutional disorder and then adopt the coherent potential approximation. The magnetocrystalline anisotropy energy Δ E is roughly proportional to the power of the long-range order parameter S , i.e., Δ E ∝ S n ( n ∼1.6–2.4). We also discuss the relationship between the magnetocrystalline anisotropy energy and the orbital magnetic moment. In the same compositional system with different degrees of order, the difference between the orbital magnetic moment in the magnetic easy axis and that in the hard one is proportional to Δ E . However, the coefficient corresponding to t...