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.

Nordheim dependence in the surface resistivity of disordered overlayers

Abstract: A multiple scattering calculation is used to compute the surface resistivity of Cu(100), Al(100), and Al(111) surfaces as a function of coverage by a disordered overlayer of Cu or Al adatoms. The Bloch states of the semi-infinite bulk are described by a layer-Korringa–Kohn–Rostoker calculation combined with the coherent potential approximation to represent the carrier scattering by the disordered overlayer. The diffuse scattering of carriers by the surface disorder results in a Nordheim, or quasiparabolic, dependence of the induced surface resistivity upon the coverage. This result confirms the qualitative behavior observed in a prior calculation using the average t-matrix approximation where the surface was modeled as a random distribution of s-wave scatterers in front of a hard-wall potential representing the surface barrier [D. L. Lessie and E. R. Crosson, J. Appl. Phys. 59, 504 (1986)].

Nonempirical simulations of boron interstitials in tungsten

Abstract: Formation of W}B solid solutions for di!erent concentrations of boron is studied within nonempirical modeling. We consider ordering tendencies, study electronic structure and provide total energy calculations on the basis of coherent potential approximation. We also study an equilibrium structure of a lattice with 11 1 grain boundary in pure tungsten and in tungsten-based solid solution with boron additives. We used simulated annealing methods in atomistic simulations to obtain relaxed con"gurations of the lattice in the vicinity of grain boundary. 2001 Elsevier Science B.V. All rights reserved.

Magnetic properties in the high-temperature cuprate superconductors with nonmagnetic impurities

Abstract: We study the effects of nonmagnetic impurities on the magnetic properties of the ${\mathrm{CuO}}_{2}$ planes in high-temperature cuprate superconductors, on the basis of the d-p model, within the fluctuation exchange approximation and the coherent potential approximation. The spin correlations between electrons in the neighborhood of the impurity are decreased, due to electron repulsion by the impurity. The antiferromagnetic contribution to the dynamical spin susceptibility decreases due to the nonmagnetic impurities, and the calculated superconducting temperature correspondingly decreases.

Methods of electron transport in ab initio theory of spin stiffness

Abstract: We present an ab initio theory of the spin-wave stiffness tensor for ordered and disordered itinerant ferromagnets with pair exchange interactions derived from a method of infinitesimal spin rotations. The resulting formula bears an explicit form of a linear-response coefficient which involves one-particle Green's functions and effective velocity operators encountered in a recent theory of electron transport. Application of this approach to ideal metal crystals yields more reliable values of the spin stiffness than traditional ill-converging real-space lattice summations. The formalism can also be combined with the coherent potential approximation for an effective-medium treatment of random alloys, which leads naturally to an inclusion of disorder-induced vertex corrections to the spin stiffness. The calculated concentration dependence of the spin-wave stiffness of random fcc Ni-Fe alloys can be ascribed to a variation of the reciprocal value of alloy magnetization. Calculations for random iron-rich bcc Fe-Al alloys reveal that their spin-wave stiffness is strongly reduced owing to the atomic ordering; this effect takes place due to weakly coupled local magnetic moments of Fe atoms surrounded by a reduced number of Fe nearest neighbors.

First-Principles Study on the Magnetic Damping of Transition Metals in the Presence of Spin Fluctuation

Abstract: We calculated, from first principles, the Landau frequency $\lambda $ to investigate the effects of spin fluctuation on the magnetic damping of Fe and Ni metals as well as $L1_{0}$ -type ordered alloys, namely, FePt, CoPt, FePd, and MnAl, assuming random arrangements of spins as an effect of thermal activation through coherent potential approximation and the tight-binding linear muffin-tin orbital method. The results show that the $\lambda $ of these systems are similar to conductivity in the weak spin fluctuation region and resistivity in the strong fluctuation region as well as in the lattice vibration system. Qualitatively, this behavior is consistent with the experimental results for temperature dependence of the $\lambda $ of Fe and Ni metals. For $L1_{0}$ -type alloys, the magnitude of the magnetic damping is in the following (decreasing) order: CoPt, FePt, FePd, and MnAl.