Ab initio analyses of A(2)IrO(4) (A=Sr,Ba) are presented. Effective Hubbard-type models for Ir 5d t(2g) manifolds downfolded from the global band structure are solved based on the dynamical mean-field theory. The results for A=Sr and Ba correctly reproduce paramagnetic metals undergoing continuous transitions to insulators below the Néel temperature T(N). These compounds are classified not into Mott insulators but into Slater insulators. However, the insulating gap opens by a synergy of the Néel order and significant band renormalization, which is also manifested by a 2D bad metallic behavior in the paramagnetic phase near the quantum criticality.

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The popular local-density approximation neglects long-range correlations which, in the presence of the rapid rate of change of the electron density at the surface, lead to observable effects. We evaluate the exchange-correlation potential V xc for the electron gas-vacuum interface from the knowledge of the electron self-energy Z xc in the GW approximation. The electron-electron correlations built into I xc automatically produce an imagelike surface barrier. Our result for V xc is the basis of a nonlocal densityfunctional calculation of the electronic structure of Al(lOO) which yields a Rydberg series of image states from first principles. PACS numbers: 73.20.-r, 71.10,+x The major advances witnessed in the last two decades in the quantitative computation of ground-state properties of condensed matter systems are to a large extent due to the development of density-functional theory [1] into a powerful tool for dealing with the complicated system of 10 23 interacting electrons. Now, in the implementation of the density-functional scheme for a metal surface one must in principle account for the fact that the very presence of the surface introduces a source of inhomogeneity on a microscopic scale. However, in the widely used (and, for many purposes, very successful [2]) local-density approximation (LDA) [1], this feature of the surface problem is simply ignored in the treatment of the crucial electron-electron interactions.Because of its neglect of long-range correlations, the LDA gives rise to a surface barrier with a qualitatively incorrect asymptotic behavior (exponential decay, rather than the expected inverse power [3]). This failure of the LDA is experimentally relevant; new surface-sensitive techniques have produced a wealth of data on observables and processes influenced by the image tail of the surface barrier, such as binding energies and lifetimes of image potential-bound surface states [4], tunneling currents in the scanning-tunneling microscope [5], resonant-tunneling rates for ion-surface collisions [6], etc.In this Letter we report a first-principles evaluation of the exchange-correlation potential (V xc ) for the electron gas-vacuum interface. We proceed by solving an exact integral equation relating V xc and the electron self-energy. The main physical ingredients of the self-energy, namely, its energy dependence and long-range correlations, and their interplay with the extreme inhomogeneity