Self band structure calculations

Cortona P 1991 Self-consistently determined properties of solids without band structure calculations Phys. Rev. B 44 8454... 

Van der Woude and Miedema [335] have proposed a model for the interpretation of the isomer shift of Ru, lr, Pt, and Au in transition metal alloys. The proposed isomer shift is that derived from a change in boundary conditions for the atomic (Wigner-Seitz) cell and is correlated with the cell boundary electron density and with the electronegativity of the alloying partner element. It was also suggested that the electron density mismatch at the cell boundaries shared by dissimilar atoms is primarily compensated by s —> electron conversion, in agreement with results of self-consistent band structure calculations. 

Early band structure calculations for the actinide metals were made both with and without relativistic effects. As explained above, at least the mass velocity and Darwin shifts should be included to produce a relativistic band structure. For this reason we shall discuss only the relativistic calculations. There were some difficulties with the f-band structure in these studies caused by the f-asymptote problem , which have since been elegantly solved by linear methods . Nevertheless the non-self-consistent RAPW calculations for Th through Bk indicated some interesting trends that have also been found in more recent self-consistent calculations ... 

To probe the electronic structures of the materials in the solid state, band structure calculations on the crystal structure of compound 22 were carried out. The results obtained by using the linear muffin-tin orbital (LMTO) self-consistent field (SCF) method support the interpretation that compounds 22 (R1 = Me, Et R2 = H) are small-band-gap semiconductors. 

The energy gap obtained in such band-structure calculations is the one called HOMO-LUMO gap in molecular calculations, i.e., the difference between the energies of the highest occupied and the lowest unoccupied singleparticle states. Neglect of the derivative discontinuity A, defined in Eq. (65), by standard local and semilocal xc functionals leads to an underestimate of the gap (the so-called band-gap problem ), which is most severe in transition-metal oxides and other strongly correlated systems. Self-interaction corrections provide a partial remedy for this problem [71, 72, 73, 74],... 

A partial justihcation for the interpretation of the KS eigenvalues as starting point for approximations to quasi-particle energies, common in band-structure calculations, can be given by comparing the KS equation with other self-consistent equations of many-body physics. Among the simplest such equations are the Hartree equation... 

Another scheme known as LDA-t-U has been developed [121-125] to add aspects of the Hubbard model [126,127] to self-consistent band structure calculations. It introduces additional interactions which depend on the occupation of the individual orbitals, and in that way an extra symmetry... 

This volume proposes to describe one particular method by which the self-consistent electronic-structure problem may be solved in a highly efficient manner. Although the technique under consideration, the Linear Muffin-Tin Orbital (LMTO) method, is quite general, we shall restrict ourselves to the case of crystalline solids. That is, it will be shown how one may perform self-consistent band-structure calculations for infinite crystals, and apply the results to estimate ground-state properties of real materials. 

To avoid misunderstanding I mention that the above scaling cycle is used in the self-consistency procedure mainly to reduce the number of band-structure calculations needed. If one wants very accurate self-consistent bands one must include an energy-band calculation at the end of each self-consistent scaling cycle. However, the scaling procedure is so efficient that fully converged bands of most metals may be obtained with only one or two band calculations included in the complete self-consistency procedure. 

The structural similarity of MgAgAs-type compounds with Heusler alloys and with the transition-metal based half-metallic ferromagnets (de Groot et al. 1983) has provoked band-structure calculations of UNiSn (Mueller et al. 1987, Albers et al. 1987). Self-consistent-field scalar relativistic spin-polarized calculations neglecting the spin-orbit coupling revealed the following features of the valence band ... 

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