In past decades the scientific community has been looking for a reliable first-principles method to predict the electronic structure of solids with high accuracy. Here we present an approach which we call the quasiparticle self-consistent approximation. It is based on a kind of self-consistent perturbation theory, where the self-consistency is constructed to minimize the perturbation. We apply it to selections from different classes of materials, including alkali metals, semiconductors, wide band gap insulators, transition metals, transition metal oxides, magnetic insulators, and rare earth compounds. Apart from some mild exceptions, the properties are very well described, particularly in weakly correlated cases. Self-consistency dramatically improves agreement with experiment, and is sometimes essential. Discrepancies with experiment are systematic, and can be explained in terms of approximations made.

We have developed a new type of self-consistent scheme within the GW approximation, which we call quasiparticle self-consistent GW (QSGW ). We have shown that QSGW describes energy bands for a wide-range of materials rather well, including many where the local-density approximation fails. QSGW contains physical effects found in other theories such as LDA+U , SIC and GW in a satisfactory manner without many of their drawbacks (partitioning of itinerant and localized electrons, adjustable parameters, ambiguities in double-counting, etc.). We present some theoretical discussion concerning the formulation of QSGW , including a prescription for calculating the total energy. We also address several key methodological points needed for implementation. We then show convergence checks and some representative results in a variety of materials.

We present a new kind self-consistent GW approximation (scGW) based on the all-electron, fullpotential LMTO method. By iterating the eigenfunctions of the GW Hamiltonian, self-consistency in both the charge density and the quasiparticle spectrum is achieved. We explain why this form of self-consistency should be preferred to the conventional one. Then some results for Si are shown as a representative semiconductor, to establish agreement with a prior scGW calculation. Finally we consider many details in the electronic structure of the antiferromagnetic insulators MnO and NiO. Excellent agreement with experiment is shown for many properties, suggesting that a Landau quasiparticle (energy band) picture of MnO and NiO provides a reasonable description of electronic structure even in these correlated materials. The GW approximation (GWA) of Hedin[1] is generally believed to accurately predict excited-state properties, and in particular improve on the local density approximation (LDA), whose limitations are well known, e.g. to underestimate bandgaps semiconductors and insulators. Usually GWA is computed as 1-shot calculation starting from the LDA eigenfunctions and eigenvalues; the self-energy Σ is approximated as Σ = iG LDA W LDA , where G LDA is a bare Green function constructed from LDA eigenfunctions, and W LDA is the screened Coulomb interaction constructed from G LDA in the random phase approximation (RPA). However, establishing the validity of the 1-shot approach has been seriously hampered by the fact that nearly all calculations to date make further approximations, e.g. computing Σ from valence electrons only; the plasmon-pole approximations; and the pseudopotential (PP) approximation to deal with the core. Only recently when reliable all-electron implementations have begun to appear, has it been shown that the 1-shot GWA with PP leads to systematic errors [2,3,4]. There is general agreement among the all-electron calculations (see Table I) that the Γ-X transition in Si is underestimated when Σ = iG LDA W LDA . And we have shown previously[2] that the tendency for Σ = iG LDA W LDA to underestimate gaps is almost universal in semiconductors. This is reasonable because W LDA overestimates the screening owing to the LDA small band gaps. G constructed from quasiparticles (QP) with a wider gap (e.g. a self-consistent G) reduces the screening, and therefore generates GW with a wider gap. However, there are many possible ways to achieve selfconsistency. The theoretically simplest (and internally consistent) is the fully self-consistent scheme (scGW), which is derived through the Luttinger-Ward functional with the exchange-correlation energy approximated as the sum of RPA ring diagrams. Then W is evaluated as W = v(1 − vP ) −1 with the proper part of the polarization function P = −iG × G. However, such a construction may not give reasonable W [5], resulting in a poor G, for the following reason. If Σ is ω-dependent, G can be partitioned into a QP part and a residual satellite part. The QP part consists of terms whos...

Based on the concept of band-bending at metal/semiconductor interfaces as an energy filter for electrons, we present a theory for the enhancement of the thermoelectric properties of semiconductor materials with metallic nanoinclusions. We show that the Seebeck coefficient can be significantly increased due to a strongly energy-dependent electronic scattering time. By including phonon scattering, we find that the enhancement of ZT due to electron scattering is important for high doping, while at low doping it is primarily due to decrease of the phonon thermal conductivity. 72.15.Eb, II. CHARGE AND HEAT TRANSPORT IN BULK PBTEIn this section we will review the expressions 7,8,9 for the charge and heat transport in bulk PbTe with n-type

We predict and quantitatively evaluate the unique possibility of concentrating the energy of an ultrafast excitation of a nanosystem in a small part of the whole system by means of coherent control (phase modulation of the exciting ultrashort pulse). Such concentration is due to dynamic properties of surface plasmons and leads to local fields enhanced by orders of magnitude. This effect exists for both "engineered" and random nanosystems. We also discuss possible applications.