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Showing papers on "Coherent potential approximation published in 1999"


Book
01 Jul 1999
TL;DR: In this article, the authors present a comprehensive review of the results of the last term in equation (2.18) of UP and UR and evaluate the performance of these terms.
Abstract: 1. Essentials 1.1 Lorentz field 1.2 Clausius-Mossotti 1.3 Maxwell-Garnett 1.4 Bruggeman 1.5 Green's functions formulation 1.6 Summary and equivalence 2. Rigorous results 2.1 Introduction 2.2 Variational bounds 2.3 The concentric shell model 2.4 Spectral representation 2.5 Exactly soluble models 2.6 Reciprocity theorems 3. Dynamical theory 3.1 Introduction 3.2 Review 3.3 Macroscopic electrodynamics 3.4 Quasi-static regime 3.5 Displacement current and wave scattering 3.6 Mie scattering 3.7 Dynamical effective medium theory 3.8 Open problems 4. Limitations and beyond 4.1 Introductory remarks 4.2 Higher order terms 4.3 Percolation and criticality 4.4 Mie resonances 4.5 Multiple scattering 4.6 Competing interactions 4.7 Two body effective medium 4.8 Non-equilibrium 5. Related theories 5.1 Comments 5.2 Coherent potential approximation 5.3 Feynman diagrams 5.4 Localization of light 5.5 Classical theory of liquids 5.6 Density functional theories 5.7 Hubbard model, CPA and DFT 5.8 Summary 6. EMT applications 6.1 Introduction 6.2 Electric and magnetic properties 6.3 Optical properties 6.4 Granular high Tc superconductors 6.5 Hydrodynamics of suspensions 6.6 Mechanical properties 6.7 Nonlinear composites 6.8 Conclusions Appendices A.1 Stationery properties of UP and UR A.2 Evaluation of the last term in equation (2.18)

668 citations


Journal ArticleDOI
TL;DR: In this article, the electronic structure of the half-metallic ferromagnet NiMnSb with three different types of atomic disorder is calculated using the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation.
Abstract: The electronic structure of the half-metallic ferromagnet NiMnSb with three different types of atomic disorder is calculated using the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation. Results indicate the presence of minority-spin states at the Fermi energy for degrees of disorder as low as a few percent. The resulting spin polarization below 100% is discussed in the light of experimental difficulties confirming the half-metallic property of NiMnSb thin films directly.

222 citations


Journal ArticleDOI
TL;DR: In this article, a combination of numerical techniques was used to calculate the heat of solution, surface energies and segregation energies for a large number of metals and alloys, including Ni and Rh 75 Pt 25.

198 citations


Journal ArticleDOI
TL;DR: In this paper, the spectrum of a random matrix, whose elements depend on the euclidean distance between points randomly distributed in space, is studied and a high density expansion is constructed, which can be resummed producing an approximation to the spectrum similar to the Coherent Potential Approximation for disordered systems.

110 citations


Journal ArticleDOI
TL;DR: A systematic study of the spectrum of a random matrix, whose elements depend on the euclidean distance between points randomly distributed in space, is introduced through its representation by a field theory, which can easily construct a high density expansion.
Abstract: We study the spectrum of a random matrix, whose elements depend on the Euclidean distance between points randomly distributed in space. This problem is widely studied in the context of the Instantaneous Normal Modes of fluids and is particularly relevant at the glass transition. We introduce a systematic study of this problem through its representation by a field theory. In this way we can easily construct a high density expansion, which can be resummed producing an approximation to the spectrum similar to the Coherent Potential Approximation for disordered systems.

103 citations


Journal ArticleDOI
TL;DR: In this paper, the attenuation of Rayleigh waves due to their interaction with resonating structures randomly distributed on the surface of a semi-infinite elastic medium is calculated along with the Rayleigh wave frequency.
Abstract: The attenuation of Rayleigh waves due to their interaction with resonating structures randomly distributed on the surface of a semi-infinite elastic medium is calculated along with the Rayleigh wave frequency. The resonating structures are modeled by single oscillators coupled to the displacement field at the surface of the elastic medium. Using the coherent potential approximation, the dependence of the frequency and damping constant of the Rayleigh waves on wave vectors are determined for various values of the concentration of oscillators on the surface.

44 citations


Journal ArticleDOI
01 Oct 1999-EPL
TL;DR: In this article, the authors present near infrared total transmission measurements through samples of randomly packed silicon powders at different wavelengths and analyze in detail the scattering properties and the effects of residual absorption.
Abstract: We present near infrared total transmission measurements through samples of randomly packed silicon powders. At different wavelengths we analyze in detail the scattering properties and the effects of residual absorption. The lowest value of kls, where k is the wave vector and ls is the scattering mean free path, is 3.2. We also observe that kls is nearly constant over a wide wavelength range. This phenomenon is associated with the high polydispersity of the particles. We use the energy density coherent potential approximation to explain our measurements.

43 citations


Journal ArticleDOI
TL;DR: In this article, the magnetic structure of γ-FeMn was studied using the Korringa-Kohn-Rostocker multiple-scattering approach in conjunction with an extension of the single site coherent potential approximation to noncollinear magnetic structures.
Abstract: We use first principles electronic structure techniques to study the magnetic structure of γ-FeMn using the Korringa–Kohn–Rostocker multiple-scattering approach in conjunction with an extension of the single site coherent potential approximation to noncollinear magnetic structures. Our results show that the noncollinear 3Q and 2Q structures are both stable solutions with the former being slightly lower in energy. The collinear solutions could only be converged in a traditional spin-polarized calculation and are unstable in a noncollinear treatment.

39 citations


Journal ArticleDOI
TL;DR: In this article, the double exchange model with quantum local spins S is studied; an equation of motion approach is used and decoupling approximations analogous to Hubbard's are made.
Abstract: The double exchange (DE) model with quantum local spins S is studied; an equation of motion approach is used and decoupling approximations analogous to Hubbard's are made. Our approximate one-electron Green function G is exact in the atomic limit of zero bandwidth for all S and band filling n. Since as it reduces to the result of a dynamical coherent potential approximation (CPA) due to Kubo, we regard our approximation as a many-body generalization of Kubo's CPA. G is calculated self-consistently for general S in the paramagnetic state and for S = 1/2 in a state of arbitrary magnetization. The electronic structure is investigated and four bands per spin are obtained centred on the atomic limit peaks of the spectral function. A resistivity formula appropriate to the model is derived from the Kubo formula and the paramagnetic state resistivity is calculated; insulating states are correctly obtained at n = 0 and n = 1 for strong Hund coupling. Our prediction for is much too small to be consistent with experiments on manganites so we agree with Millis et al that the bare DE model is inadequate. We show that the agreement with experiment obtained by Furukawa is due to his use of an unphysical density of states.

36 citations


Journal ArticleDOI
TL;DR: In this article, a Coherent Potential Approximation (CPA) was developed for s-wave and d-wave superconductivity in disordered systems, and the CPA formalism reproduces the standard pair-breaking formula, the selfconsistent Born Approximate and the self-consistent T-matrix approximation in the appropriate limits.
Abstract: A Coherent Potential Approximation is developed for s–wave and d–wave superconductivity in disordered systems. We show that the CPA formalism reproduces the standard pair-breaking formula, the self-consistent Born Approximation and the self-consistent T-matrix approximation in the appropriate limits. We implement the theory and compute Tc for s–wave and d–wave pairing using an attractive nearest neighbor Hubbard model featuring both binary alloy disorder and a uniform distribution of scattering site potentials. We determine the density of states and examine its consequences for low temperature heat capacity. We find that our results are in qualitative agreement

28 citations


Journal ArticleDOI
TL;DR: In this article, the ground states of interface polarons in a realistic heterojunction potential are investigated by considering the bulk and the interface optical phonon influence, and an LLP-like method is adopted to obtain the polaron effect.
Abstract: The ground states of interface polarons in a realistic heterojunction potential are investigated by considering the bulk and the interface optical phonon influence. A self-consistent heterojunction potential is used and an LLP-like method is adopted to obtain the polaron effect. The numerical computation has been done for the Zn1-xCdxSe/ZnSe system to obtain the polaron ground state energy, self energy and effective mass parallel to the interface. A simplified coherent potential approximation is developed to obtain the parameters of the ternary mixed crystal and the energy band offset of the heterojunction. It is found that at small Cd concentration the bulk longitudinal optical phonons give the main contribution for lower areal electron densities, whereas the interface phonon contribution is dominant for higher areal electron densities. The interface polaron effect is weaker than the effect obtained by the three dimensional bulk phonon and by the two dimensional interface phonon models.

Journal ArticleDOI
TL;DR: In this article, the surface region of metallic alloys and the surface segregation are studied in terms of an effective Ising Hamiltonian, whose parameters (often called effective cluster interactions) are determined from ab initio electronic structure calculations using the force theorem.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the thermal depinning of flux lines on the irreversibility line from a viewpoint of thermodynamics using the coherent potential approximation theory, a kind of statistical theory for flux pinning.
Abstract: The thermal depinning of flux lines on the irreversibility line is investigated from a viewpoint of thermodynamics using the coherent potential approximation theory, a kind of statistical theory for flux pinning. The effect of thermal activation is approximately introduced by making the pinning potential shallow following the theoretical scheme by Yamafuji et al. It is shown that the thermal depinning is the transition of the second order. Since the vortex glass–liquid transition, which is considered to be identical with the thermal depinning, is originally predicted to be the second-order transition, the present theoretical result is reasonable. The present result also suggests that the irreversibility line observed at higher temperatures and at lower fields than the critical point for weakly pinned superconductors is also the transition line of the second order. In addition, it is shown that the degree of disorder of the flux line lattice decreases fast, suggesting a quick recovery of the order of the lattice with elevating temperature above the critical temperature.

Journal ArticleDOI
TL;DR: In this article, the electronic band structure of the InP-lattice matched alloys In0.53Ga0.47As and In 0.52Al0.48As is investigated using a non-local empirical pseudopotential including spin-orbit interaction.
Abstract: The electronic band structure of the InP-lattice matched alloys In0.53Ga0.47As and In0.52Al0.48As is investigated using a non-local empirical pseudopotential including spin–orbit interaction. Pseudopotential parameters are obtained by fitting the virtual crystal band structure immediately to available experimental data for the alloys. Results are presented for the band structures and effective masses in In0.53Ga0.47As and In0.52Al0.48As. Comparison of the band structures is made against available results from a quasiparticle calculation and a model pseudopotential calculation within the coherent potential approximation.

Journal ArticleDOI
TL;DR: In this article, an attempt is made to explain the correlation between the spin polarization of the tunneling current in ferromagnet/Al2O3/Al tunnel junction experiments and the magnetic moment in the ferromagnets.
Abstract: The correlation between the spin polarization of the tunneling current in ferromagnet/Al2O3/Al tunnel junction experiments and the magnetic moment in ferromagnets has been a mystery [Phys. Rev. B 16, 4907 (1977) and Phys. Rep. 238, 173 (1994)]. In this study, an attempt is made to explain this correlation. By assuming that the s electrons are responsible for the tunneling, the tunneling currents are proportional to the s density of states at the Fermi level [Phys. Rev. B 8, 3252 (1973)]. A tight-binding coherent potential approximation model for itinerant magnetism is applied to calculate the band structure of Fe- and Ni-based alloys [Rev. Mod. Phys. 46, 465 (1974)]. The Slater–Pauling curve for the bulk magnetic moment is recovered, and the spin polarization of the s electrons at the Fermi level is found to correlate well with the magnetic moment. The calculation is carried out in a model where the approximate band structure of an alloy is calculated by using two extra tight-binding parameters besides th...

Journal ArticleDOI
TL;DR: In this article, it was shown that a disordered system of coupled classical harmonic oscillators with a continuous distribution of coupling parameters exhibits generally a low-frequency enhancement (boson peak) of the density of states, as compared with the Debye law.
Abstract: It is demonstrated that a disordered system of coupled classical harmonic oscillators with a continuous distribution of coupling parameters exhibits generally a low-frequency enhancement (“boson peak”) of the density of states, as compared with the Debye law. This phenomenon is most pronounced if the system is close to an instability. This is shown by means of a scalar model on a simple cubic lattice. The force constants are assumed to fluctuate from bond to bond according to a Gaussian distribution which is truncated at its lower end. The model is solved for the density of states and the one-phonon dynamic structure factor S(q, ω) by applying the two-site coherent potential approximation (CPA). The results for the density of states are in very good agreement with a numerical evaluation of the same model.

Journal ArticleDOI
TL;DR: In this article, the functional dependence of the giant magnetoresistance with respect to the relative angle between the orientations of the magnetization in the magnetic slabs of a trilayer system is calculated by using the Kubo-Greenwood formula for electrical transport together with the fully-relativistic spin- polarized screened Korringa-Kohn-Rostoker method for semi-innite systems and the coherent potential approximation.
Abstract: The functional dependence of the giant magnetoresistance (GMR) with respect to the relative angle between the orientations of the magnetization in the magnetic slabs of a trilayer system is calculated by using the Kubo-Greenwood formula for electrical transport together with the fully-relativistic spin- polarized screened Korringa-Kohn-Rostoker method for semi-innite systems and the coherent potential approximation. It is found that the functional dependence of the GMR is essentially of the form (1 cos').

Book ChapterDOI
01 Jan 1999
TL;DR: In this article, a recently developed ab initio approach to the electronic structure of substitutionally disordered alloys and their surfaces is reviewed, based on the tight-binding linear muffin-tin orbital (TB-LMTO) method in the atomic sphere approximation which provides a physically transparent solution of the one-electron problem in metallic materials, and the coherent potential approximation (CPA) for a mean-field treatment of the substitutional randomness, and surface Green functions for a proper description of the true semi-infinite geometry of surfaces and interfaces.
Abstract: A recently developed ab initio approach to the electronic structure of substitutionally disordered alloys and their surfaces is reviewed. It is based on (i) the tight-binding linear muffin-tin orbital (TB-LMTO) method in the atomic sphere approximation which provides a physically transparent solution of the one-electron problem in metallic materials, (ii) the coherent potential approximation (CPA) for a mean- field treatment of the substitutional randomness, and (iii) the surface Green functions for a proper description of the true semi-infinite geometry of surfaces and interfaces. Theoretical formulation of fundamental electronic quantities, both site-diagonal (charge densities, densities of states) and site non-diagonal (the Bloch spectral functions) is presented. Transformation properties of the LMTO-CPA theory as well as specific problems of application of the local density approximation to random alloys are briefly discussed and basic algorithms employed in the numerical implementation of the formalism are described.

Journal ArticleDOI
TL;DR: In this article, a many-body coherent potential approximation (CPA) was used to study the double exchange (DE) model with quantum local spins S, both for S = 1/2 and for general S in the paramagnetic state.
Abstract: Previously a many-body coherent potential approximation (CPA) was used to study the double-exchange (DE) model with quantum local spins S, both for S = 1/2 and for general S in the paramagnetic state. This approximation, exact in the atomic limit, was considered to be a many-body extension of Kubo's one-electron dynamical CPA for the DE model. We now extend our CPA treatment to the case of general S and spin polarization. We show that Kubo's one-electron CPA is always recovered in the empty-band limit and that our CPA is equivalent to dynamical mean-field theory in the classical spin limit. We then solve our CPA equations self-consistently to obtain the static magnetic susceptibility in the strong-coupling limit. As in the case of the CPA for the Hubbard model, we find unphysical behaviour in at half-filling and no magnetic transition for any finite S. We identify the reason for this failure of our approximation and propose a modification which gives the correct Curie-law behaviour of at half-filling and a transition to ferromagnetism for all S.

Journal ArticleDOI
Abstract: Though the importance of chemisorption at the electrochemical interface is well recognized, an electronic level description for the same still remains in a nascent stage. The present work specifically addresses this problem. An appropriate model Hamiltonian based formalism is proposed for a random adsorbate layer with arbitrary coverage and the ensuing two-dimensional band formation by metallic adsorbates in the monolayer regime. The coherent potential approximation is employed to handle the randomness. The adsorbate self-energy is evaluated explicitly using the density of states for the substrate band. This takes us beyond the conventional wide-band approximation and removes the logarithmic divergence associated with the binding energy calculations. The formalism is applied to the electrosorption of copper ion on gold electrode, and the coverage dependence of adsorbate charge, binding energy, and adsorbate density of states are determined. The analysis predicts a unique charge configuration of copper ads...

Book ChapterDOI
01 Jan 1999
TL;DR: In this article, the authors present an effective method for the study of the temperature dependence of the interlayer exchange coupling between two, in general noncollinearly aligned magnetic slabs embedded in a non-magnetic spacer.
Abstract: Ab initio formulations of the interlayer exchange coupling (IEC) between two, in general non-collinearly aligned magnetic slabs embedded in a non-magnetic spacer are reviewed whereby both the spacer and the magnetic slabs as well as their interfaces may be either ideal or random. These formulations are based on the spinpolarized surface Green function technique within the tight-binding linear muffin-tin orbital method, the Lloyd formulation of the IEC, and the coherent potential approximation using the vertex-cancellation theorem. We also present an effective method for the study of the temperature dependence of the IEC. The periods, amplitudes, and phases are studied in terms of discrete Fourier transformations, the asymptotic behavior of the IEC is briefly discussed within the stationary-phase method. Numerical results illustrating the theory are presented.

Journal ArticleDOI
TL;DR: In this article, the authors performed atomistic simulations of the properties of the Σ3 grain boundary in W and demonstrated the influence of boron additive on the resistance of the grain boundary with respect to different shifts.
Abstract: We perform the atomistic simulations of the properties of the Σ3 grain boundary in W and demonstrate the influence of boron additive on the resistance of the grain boundary with respect to different shifts. The interatomic potentials used in these simulations are obtained from ab initio total energy calculations. These calculations are carried out in the framework of density functional theory in the coherent potential approximation. The recursion procedure to extract A–B type interatomic potentials is suggested.

Journal ArticleDOI
TL;DR: In this article, a dynamical coherent potential approximation (DCPA) is formulated within the Hartree approximation for an exciton interacting with phonons, which is equivalent to the well-known single-site approximation DCPA.

Journal ArticleDOI
TL;DR: In this article, the spin-wave theory and the coherent potential approximation are applied to a spin S Heisenberg antiferromagnet with nonmagnetic impurities on square lattice.
Abstract: The spin-wave theory and the coherent potential approximation are applied to a spin S Heisenberg antiferromagnet with nonmagnetic impurities on square lattice. The impurity effects are taken into account by substituting S (1- x ) for S and using the coherent potential approximation to the exchange interaction, where x is the impurity concentration. At T =0 for S =1/2 the critical impurity concentration x c of the Neel state is 0.303 and the percolation threshold x p is 0.500. The ground state in x c < x < x p is the disordered state with the spin gap. For S ≥1 the long range Neel order vanishes at x p =0.500. These results explain qualitatively the experimental results of La 2 Cu 1- x Mg x O 4 ( S =1/2) and K 2 Mn 1- x Mg x F 4 ( S =5/2). The difference of x c between these materials is caused by the decrease in the magnitude of the effective spin with impurity doping. The spin gap is expected to be observed for La 2 Cu 1- x Mg x O 4 in x c < x < x p at low temperatures.

Book ChapterDOI
TL;DR: In this paper, the density functional formalism within the local density approximation (LDA), in which the electron-correlation part is guessed on the basis of the homogeneous electron gas model, has proved to be a highly reliable method for the evaluation of the ground state properties.
Abstract: A general scheme for determination of the electronic structure of solids with correlated electrons is still missing. The density functional formalism within the local density approximation (LDA), in which the electron-correlation part is guessed on the basis of the homogeneous electron gas model, has proved to be a highly reliable method for the evaluation of the ground state properties’. On the other hand, there are many examples of the failure of the LDA, e.g., the study of the excitation spectra of solids or the evaluation of the gap in insulators and semiconductors. Another example of the failure of the LDA are solids whose electronic structure is better described in terms of atomic-like electronic states rather than in terms of the homogeneous electron gas model on which the LDA is based.

Journal ArticleDOI
TL;DR: The electronic structure of Cd 0.985 Fe 0.015 Te has been studied by resonant photoemission in the synchrotron radiation photon energy range from 48 to 67 eV as mentioned in this paper.

Journal ArticleDOI
TL;DR: Fuks and S. Dorfman as mentioned in this paper investigated the concentration dependence of the energy parameters which describe the stability of the disordered Fe-Al alloy and the phase transformation in B2 and DO3 phases.
Abstract: In the nonempirical approach based on the coherent potential approximation (CPA), we investigate the concentration dependence of the energy parameters which describe the stability of the disordered Fe–Al alloy and the phase transformation in B2 and DO3 phases. We based our calculations on the most attractive feature of CPA to be applicable to the direct calculations of the electronic structure of random or partially ordered alloys. The procedure described in our study [D. Fuks and S. Dorfman, Solid State Commun. 90, 773 (1994)] for the estimation of the parameters of the effective mixing potential is realized for different phases in the stoichiometric composition. Calculation data for different concentrations of Fe–Al alloy are used to extract the interaction parameters V(0), V(k1), and V(k2). These energy parameters are compared with the parameters treated from the diffuse X-ray scattering data. We show that the interaction parameters for Fe–Al alloys strongly depend on the concentration. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 927–941, 1999

Journal ArticleDOI
TL;DR: In this article, the impact of short-range ordering on phonons is studied in the framework of coherent potential approximation, and the effects of MI on the dielectric response due to phonons are calculated using the modified Maxwell-Garnett approach.
Abstract: Possible types and formation mechanisms for the correlated cation distributions in CdxHg1−xTe alloys, including short-range order (SRO) in the mixed sublattice and composition microinhomogeneities (MI), are discussed. The impact of SRO (ordering or clustering) on phonons is studied in the framework of the coherent potential approximation. It is shown that two peaks of the spectral density of phonon states with $$\overrightarrow q $$ =0 (HgTe-like and CdTe-like modes) move toward and away from their positions in end member crystals due to clustering and ordering, respectively. Short-range ordering also activates (HgTe-like and CdTe-like states of the Brillouin zone edge, but this effect is small. The effects of composition MI on the dielectric response due to phonons are considered and an effective dielectric function is calculated using the modified Maxwell-Garnett approach. It is shown that separate inclusions of different composition produce extra modes of the Frohlich type in FIR spectra of CdxHg1−x Te. It is argued that this is a more plausible explanation of the experimenatally observed ‘cluster’ mode (133 cm−1 in Raman and 135 cm−1 in FIR spectra) than one which previously appeared in the literature and involves atomic ordering in the mixed sublattice.

Book
01 Aug 1999
TL;DR: In this paper, a detailed theoretical investigation of the magnetic and structural properties of all the binary alloys between the 3d elements Fe, Co, Ni, and Cu is performed.
Abstract: The subject of the present thesis is a theoretical investigation of magnetism and its crystal structure dependence by means of electronic-structure calculations from first principles. The theoretical treatment is based on density functional theory and the so called linear muffin-tin orbital method is used in its full-potential version as well as in an atomic sphere approximation.A detailed theoretical investigation of the magnetic and structural properties of all the binary alloys between the 3d elements Fe, Co, Ni, and Cu is performed. Alloying effects are treated by a mean field approximation called the coherent potential approximation. Theory is able to reproduce experiments regarding both magnetic and structural properties and gives an understanding of the physics behind the formation of magnetic moments and the correlation between magnetism and structural stabilily.The magnetic anisotropy energy of especially the magnetic 3d elements Fe, Co, and Ni in their cubic ground structures and in tetragonal and trigonal structures are calculated and from this also different magnetostriction coefficients have been studied. The correlation between the orbital moment anisotropy and the total energy anisotropy is studied both by means of numerical experiments and by perturbation theory. Different theoreticalapproaches have been tested and compared.Further, the magnetic anisotropy has been studied for some intermetallic compounds, for which the anisotropy is rather large, such as MnX (X=As, Sb, Bi), VAu4, FePt.Together with experimental physicists and chemists the (Fe1-yXy)3P (X=Mn, Co) have been extensively studied regarding magnetic configurations and site preference of the different metallic elements.

Journal ArticleDOI
TL;DR: In this article, the energy stability of ultrathin epitaxial Cr overlayers on a Fe(001) substrate and their energy stability with respect to Cr-Fe interdiffusion were studied by means of ab initio electronic structure calculations.
Abstract: Itinerant magnetism of ultrathin epitaxial Cr overlayers on a Fe(001) substrate and their energy stability with respect to Cr-Fe interdiffusion were studied by means of ab initio electronic structure calculations. The latter were based on the tight-binding linear muffin-tin orbital method and the coherent potential approximation. The interdiffusion was simulated by two-dimensional substitutionally disordered Cr-Fe alloys formed within two layers at the Cr/Fe interface. For a 1 monolayer Cr film a tendency to surface alloy formation is found in contrast to a 2 monolayer Cr film which seems to be stable with respect to Fe-Cr intermixing. A comparison of the calculated results to recent experimental data is presented and an interplay between the energy stability and magnetism of the films is pointed out.