The exact density functional for the ground-state energy is strictly self-interaction-free (i.e., orbitals demonstrably do not self-interact), but many approximations to it, including the local-spin-density (LSD) approximation for exchange and correlation, are not. We present two related methods for the self-interaction correction (SIC) of any density functional for the energy; correction of the self-consistent one-electron potenial follows naturally from the variational principle. Both methods are sanctioned by the Hohenberg-Kohn theorem. Although the first method introduces an orbital-dependent single-particle potential, the second involves a local potential as in the Kohn-Sham scheme. We apply the first method to LSD and show that it properly conserves the number content of the exchange-correlation hole, while substantially improving the description of its shape. We apply this method to a number of physical problems, where the uncorrected LSD approach produces systematic errors. We find systematic improvements, qualitative as well as quantitative, from this simple correction. Benefits of SIC in atomic calculations include (i) improved values for the total energy and for the separate exchange and correlation pieces of it, (ii) accurate binding energies of negative ions, which are wrongly unstable in LSD, (iii) more accurate electron densities, (iv) orbital eigenvalues that closely approximate physical removal energies, including relaxation, and (v) correct longrange behavior of the potential and density. It appears that SIC can also remedy the LSD underestimate of the band gaps in insulators (as shown by numerical calculations for the rare-gas solids and CuCl), and the LSD overestimate of the cohesive energies of transition metals. The LSD spin splitting in atomic Ni and $s\ensuremath{-}d$ interconfigurational energies of transition elements are almost unchanged by SIC. We also discuss the admissibility of fractional occupation numbers, and present a parametrization of the electron-gas correlation energy at any density, based on the recent results of Ceperley and Alder.

Self-interaction correction to density-functional approximations for many-electron systems

We present an analysis of the performances of a parameter free density functional model (PBE0) obtained combining the so called PBE generalized gradient functional with a predefined amount of exact exchange. The results obtained for structural, thermodynamic, kinetic and spectroscopic (magnetic, infrared and electronic) properties are satisfactory and not far from those delivered by the most reliable functionals including heavy parameterization. The way in which the functional is derived and the lack of empirical parameters fitted to specific properties make the PBE0 model a widely applicable method for both quantum chemistry and condensed matter physics.

Toward reliable density functional methods without adjustable parameters: The PBE0 model

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

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Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

A method for accurate and efficient local density functional calculations (LDF) on molecules is described and presented with results The method, Dmol for short, uses fast convergent three‐dimensional numerical integrations to calculate the matrix elements occurring in the Ritz variation method The flexibility of the integration technique opens the way to use the most efficient variational basis sets A practical choice of numerical basis sets is shown with a built‐in capability to reach the LDF dissociation limit exactly Dmol includes also an efficient, exact approach for calculating the electrostatic potential Results on small molecules illustrate present accuracy and error properties of the method Computational effort for this method grows to leading order with the cube of the molecule size Except for the solution of an algebraic eigenvalue problem the method can be refined to quadratic growth for large molecules

An all‐electron numerical method for solving the local density functional for polyatomic molecules

Considerable controversy has centered on the origin of the observed two peak structure in photoemission from Ce compounds. We report results of theoretical studies of the Ce pnictides using a model based on competing screening mechanisms. It is assumed that the peak near EF arises from complete screening of the 4f hole via repopulation of the f orbital on the hole site so its contribution to the spectrum follows the ground state density of states. The second peak 2–3 eV lower in energy is viewed as being due to a poorly screened f-hole. This screening process is studied by means of self-consistent LAPW supercell calculations. In CeSb we find a peak separation of 2.71 eV compared to an experimental value of 2.5 eV, whereas in CeP we find a separation of 2.47 eV compared to 2.4 eV experiment. The poorly screened peak results primarily from d-orbital screening of the hole.

Theory of the two peak photoemission spectra in cerium compounds

Magnetism at metal-ceramic interfaces: effects of a Au overlayer on the magnetic properties of Fe/MgO(001)

In search of a soft magnetic material exhibiting high magnetization, we investigated the magnetic and structural properties of an (Fe3Co)4Nm superlattice (SL) with (m=2) and without (m=0) N doping via first principles full-potential linearized augmented plane wave calculations in order to examine the possible magnetic enhancement by (i) N addition (which has drawn considerable attention since the first report (in 1972) of a giant magnetic moment for quasistable α″-Fe16N2) and (ii) the lowered dimensionality of the SL The structural optimization was fully accomplished by total energy and atomic force calculations within the generalized-gradient approximation Despite the lattice expansion by 9% due to the N insertion, the magnetization of (Fe3Co)4N2 was found to be reduced from the value of the Fe3Co superlattice by the strong hybridization of N with Fe and Co

Hybridization reduction of the magnetization for N-doped FeCo superlattices

The photoluminescence (PL) from the wide bandgap semiconductor Tl6I4Se, a promising candidate material for gamma ray detection, was studied at low temperature. The Tl6I4Se single crystal was grown by the Bridgman method. For undoped material, we observed a single broad peak at ~1.61 eV with a full width at half maximum of 112 meV at 20 K, which is attributed to donor–acceptor pair (DAP) recombination involving shallow donors and deep acceptors. From the thermal quenching of the integrated PL peak intensity, thermal activation energy of the donor level of 52 meV was obtained. At high excitation intensities a blue-shift of peak emission energy in DAP recombination was observed. From the PL measurements, the ionization energies of the donor and acceptor levels were estimated at 52 and 290 meV, respectively.

Photoluminescent properties of semiconducting Tl6I4Se

Colossal magnetoresistive manganites (Y. Tok ura, Y.Tomioka). Spin-polarized transport and magnetoresistance in magnetic oxides (A. Gupta, J.Z. Sun). Magnetocaloric effect and magnetic refrigeration (V.K. Pecharsky, K.A. Gschneidner Jr.). Magnetoelectronics applications (G.A. Prinz). Cuprate/manganite heterostructures (A.M. Goldman, et al ). Proximity effects in superconducting/magnetic multi-layers (C.L. Chien, D.H. Reich). Heat-induced effective exchange coupling in magnetic multilayers with semiconductors (P. Walser, M. Hunziker, M. Landolt). Properties of ferromagnetic III-V semiconductors (H. Ohno). Spin dynamics and quantum transport in magnetic semiconductor quantum structures (D.D. Awschalom, N. Samarth). Aspects of spin dynamics and magnetic interactions (V.P. Antropov, B.N. Harmon, A.N. Smirnov). Macroscopic quantum tunneling in molecular magnets (B.Barbara, et al ). The molecular approach to nanoscale magnetism (A. Caneschi, et al ). Quantum computers and quantum coherence (D.P. DiVincenzo, D. Loss). Theory of spin coherence in semiconductor hetero-structures (L.J. Sham). Computer simulation studies of magnetic phase transitions (D.P. Landau). Spin polarized tunneling in ferromagnetic junctions (J.S. Moodera, G. Mathon). Current-perpendicular (CPP) magnetoresistance in magnetic metallic multilayers (J. Bass,W.P. Pratt Jr.). Effects of roughness, frustration, and antiferromagnetic order on magnetic coupling of Fe/Cr multi-layers (D.T. Pierce, et al ). Interlayer exchange coupling (M.D. Stiles). Magnetic nanowires (A. Fert, L. Piraux). Magnetic nanoparticles (R.H. Kodama). Nanophase hard magnets (G.C. Hadjipanayis). Hard/soft magnetic heterostructures: model exchange-spring magnets (E.E. Fullerton, J.S. Jiang, S.D. Bader). Magnetic nitrides (J.M.D. Coey, P.A.I. Smith). From almost zero magnetostriction to giant magnetostrictive effects: recent results (H. Szymczak). Stress and magnetic properties of surfaces and ultra-thin films (D. Sander, A. Enders, J. Kirschner). Electronic states in magnetic nanostructures ( F.J. Himpsel, et al ). Exploring the microscopic origin of magnetic anisotropies with X-ray magnetic circular dichroism (XMCD) spectroscopy (J. Stohr). Spin-orbit induced magnetic phenomena in bulk metals and their surfaces and interfaces (R. Wu, A.J. Freeman). Two dimensional magnetic phase transitions (V.L. Pokrovsky). Fermi-liquid instability at magnetic-nonmagnetic quantum phase transitions (H.v. Lohneysen). Exchange anisotropy - a review (A.E. Berkowitz, K. Takano). Magnetic superlattices and multilayers (I.K. Schuller, S. Kim, C. Leighton). Magnetization dynamics in thin films and multilayers (R.E. Camley). Mossbauer-effect studies of multilayers and interfaces (T. Shinjo, W. Keune). The limits to magnetic recording - media considerations (K. O'Grady, H. Laidler). Perpendicular magnetic recording - progress and prospects (Y. Nakamura). Recent studies in thermal activation and spin waves (M.A. Wongsam,

Arthur J Freeman

Papers

Theory of the two peak photoemission spectra in cerium compounds

Magnetism at metal-ceramic interfaces: effects of a Au overlayer on the magnetic properties of Fe/MgO(001)

Hybridization reduction of the magnetization for N-doped FeCo superlattices

Photoluminescent properties of semiconducting Tl6I4Se

Magnetism Beyond 2000