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.

Electron states in disordered layers

Abstract: The authors discuss the application of the first-principles Korringa-Kohn-Rostoker coherent potential approximation to the calculation of the electronic structure of substitutionally disordered alloys with layer geometries (surfaces, interfaces etc)-the LKKRCPA. The canonical problem of this type is that of a single layer of a random binary alloy, and they present results for a Cu0.5Pd0.5 monolayer. They compare the effective scattering amplitudes and average densities of states with those of the bulk FCC alloy, and comment on the significance of the result for the surface electronic structure of Cu-Pd alloys. They outline how disordered layers may be embedded onto or between bulk substrates in order to treat real alloy surfaces or interfaces.

Effective exchange interactions in CuAlO2-based dilute magnetic semiconductors by first-principles calculations

Abstract: Effective exchange interactions ( J ij ) between magnetic ions in CuAlO2-based dilute magnetic semiconductors (DMS) are investigated by the Korringa–Kohn–Rostoker method combined with the coherent potential approximation within the local density approximation. It is found that the J ij between magnetic ions are short-ranged and J ij 's between magnetic ions in the same Cu-plane are ferromagnetic and ones between different Cu-planes are negligible in CuAlO2-based DMS. In comparison to this, J ij 's between magnetic impurities occupied at Al-sites are slightly longer-ranged due to the stronger hybridization effect.

Alloys with Copper

Abstract: The coefficient of bulk diffusion of Rh in Cu was measured by X-ray diffraction methods described in [8, 13], at temperatures between 750 and 1075 °C. Constants: D0= 3.3 cm2/s, Q=58000 cal/mol [14].

Local moment ordering in periodic anderson model

Abstract: Strongly correlated electron systems are studied with the help of periodic Anderson model (PAM). The PAM in which highly correlated nondegenerate localized states form a subsystem is considered and the focus of study is on magnetic ordering of electrons in these localized states. In order to study the PAM, which is not amenable to exact solution, two approximate schemes are proposed. The first one is called the spectral density approximation (SDA). Guided by the atomic limit, a two-pole ansatz is made for the localized electron spectral density. The spectral weights and the quasiparticle energies are determined by a moment method. From the spectral density, the spin and energy dependent self-energy is evaluated. A principal limitation of this method is that per ansatz, the quasiparticles are of infinite lifetime. To introduce a finite lifetime, a second approximation scheme is proposed where coherent potential approximation (CPA) is applied to PAM. In order to do CPA, an alloy analogy (AA) is required. In the conventional AA, the concentrations α and the atomic levels E of the fictitious alloy are taken from the atomic limit. Since the interest is in the magnetic properties, this AA is not appropriate. Therefore, a modified AA (MAA) is proposed. In MAA, α and E are obtained using the high energy expansion of the Green's function and the self-energy. In both the approximations, the density of states and the magnetization are selfconsistently evaluated and a phase diagram is obtained. Comparison of the results of the two schemes brings out the effect of quasiparticle damping on the magnetic properties.