The widespread popularity of density functional theory has given rise to an extensive range of dedicated codes for predicting molecular and crystalline properties. However, each code implements the formalism in a different way, raising questions about the reproducibility of such predictions. We report the results of a community-wide effort that compared 15 solid-state codes, using 40 different potentials or basis set types, to assess the quality of the Perdew-Burke-Ernzerhof equations of state for 71 elemental crystals. We conclude that predictions from recent codes and pseudopotentials agree very well, with pairwise differences that are comparable to those between different high-precision experiments. Older methods, however, have less precise agreement. Our benchmark provides a framework for users and developers to document the precision of new applications and methodological improvements

The correlated quasiparticle band structure of iron, cobalt, and nickel is investigated within the dynamical mean-field theory formalism using the recently developed full-potential linear-muffin-tin-orbital-based localdensity approximation plus dynamical mean-field theory ͑LDA+ DMFT͒ code. Detailed analysis of the calculated electron self-energy, density of states, and the spectral density is presented for these metals. It has been found that all these elements show strong correlation effects for majority-spin electrons, such as strong damping of quasiparticles and formation of a satellite state below the bottom of d bands. In particular, our work clearly predicts the existence of a photoemission satellite for bcc iron. The LDA+ DMFT data for fcc nickel and cobalt ͑111͒ surfaces and bcc iron ͑001͒ surface are also presented. The electron self-energy is found to depend strongly on the number of nearest neighbors, and it practically reaches the bulk value already in the second layer from the surface. The dependence of correlation effects on the dimensionality of the problem is also discussed.

The strength of electronic correlation effects in the spin-dependent electronic structure of ferromagnetic bcc Fe(110) has been investigated by means of spin and angle-resolved photoemission spectroscopy. The experimental results are compared to theoretical calculations within the threebody scattering approximation and within the dynamical mean-field theory, together with one-step model calculations of the photoemission process. This comparison indicates that the present state of the art many-body calculations, although improving the description of correlation effects in Fe, give too small mass renormalizations and scattering rates thus demanding more refined many-body theories including non-local fluctuations.PACS numbers: 75.70. Rf, 79.60.Bm, 73.20.At, 71.15.Mb, 75.50.Bb Since more than half a century it is clear that the bandstructure together with exchange and correlation effects play an important role for the appearance of ferromagnetism in 3d transition metals and their alloys [1]. A first step toward an understanding of the electronic structure of these metals has been achieved by calculations of the single-particle band dispersion [E(k)] within the density functional theory (DFT) in the local spin-density approximation (LSDA) [2] which takes into account correlation effects only in a limited extent. It soon turned out that for the ferromagnetic 3d transition metals such as Fe, Co, and Ni, calculations beyond DFT-based theories have to be developed to take into account many-body interaction, i.e., correlation effects, which normally are described by the energy and momentum dependent complex self-energy function Σ(E, k). Here the real part Σ is related to the mass enhancement while the imaginary part Σ describes the scattering rate. One of the successful schemes for correlated electron systems is the dynamical mean-field theory (DMFT). It replaces the problem of describing correlation effects in a periodic lattice by a correlated impurity coupled to a self-consistent bath [3]. An alternative approach is the three-body scattering (3BS) approximation which takes into account the scattering of a hole into an Auger-like excitation in the valence band, formed by one hole plus an electron-hole excitation [4]. Such many-body calculations allowed the qualitative description of the quenching of majority-channel quasiparticle excitations in Co [5] or the narrowing of the Ni 3d band [6]. While the above mentioned many-body theories give an improved description of the electronic structure, the central question is, whether they also lead to a quantitative agreement with experiments.Angle-resolved photoemission spectroscopy (ARPES) is a powerful method to determine the spectral function and by comparison with the bare-particle band structure (usually approximated by DFT band structure calculations) to obtain the self-energy [7]. Moreover, the spinresolved version of this method is very useful to disentangle the complex electronic structure of ferromagnets, in particular for systems with a strong overlap between majo...

In this paper we present an accurate numerical scheme for extracting interatomic exchange parameters (J ij ) of strongly correlated systems, based on first-principles full-potential electronic structure theory. The electronic structure is modeled with the help of a full-potential linear muffin-tin orbital method. The effects of strong electron correlations are considered within the charge self-consistent density functional theory plus dynamical mean-field theory. The exchange parameters are then extracted using the magnetic force theorem; hence all the calculations are performed within a single computational framework. The method allows us to investigate how the J ij parameters are affected by dynamical electron correlations. In addition to describing the formalism and details of the implementation, we also present magnetic properties of a few commonly discussed systems, characterized by different degrees of electron localization. In bcc Fe, treated as a moderately correlated metal, we found a minor renormalization of the J ij interactions once the dynamical correlations are introduced. However, generally, if the magnetic coupling has several competing contributions from different orbitals, the redistribution of the spectral weight and changes in the exchange splitting of these states can lead to a dramatic modification of the total interaction parameter. In NiO we found that both static and dynamical mean-field results provide an adequate description of the exchange interactions, which is somewhat surprising given the fact that these two methods result in quite different electronic structures. By employing the Hubbard-I approximation for the treatment of the 4f states in hcp Gd we reproduce the experimentally observed multiplet structure. The calculated exchange parameters result in being rather close to the ones obtained by treating the 4f electrons as noninteracting core states.