Tight-binding LMTO

T emary alloys Ti-Al based materials mechanical properties of Titanium alloys hydrogenated stram effects pressure effects Tight-binding LMTO CPA... 

Faleev, S.V., Leonard, F., Stewart, D.A.and van Schilfgaarde, M. (2005) Ah initio tight-binding LMTO method for nonequilibrium electron transport in nanosystems. Phys. Rev. B, 71, 195422-1-195422-18. 

For the description of the random Hamiltonian we employ TB-LMTO formalism in the most tight binding representation . The Hamiltonian for the binary random alloy takes the form ... 

ANG AO ATA BF CB CF CNDO CPA DBA DOS FL GF HFA LDOS LMTO MO NN TBA VB VCA WSL Anderson-Newns-Grimley atomic orbital average t-matrix approximation Bessel function conduction band continued fraction complete neglect of differential overlap coherent-potential approximation disordered binary alloy density of states Fermi level Green function Flartree-Fock approximation local density of states linear muffin-tin orbital molecular orbital nearest neighbour tight-binding approximation valence band virtual crystal approximation Wannier-Stark ladder... 

In this paper we present preliminary results of an ab-initio study of quantum diffusion in the crystalline a-AlMnSi phase. The number of atoms in the unit cell (138) is sufficiently small to permit computation with the ab-initio Linearized Muffin Tin Orbitals (LMTO) method and provides us a good starting model. Within the Density Functional Theory (DFT) [15,16], this approach has still limitations due to the Local Density Approximation (LDA) for the exchange-correlation potential treatment of electron correlations and due to the approximation in the solution of the Schrodinger equation as explained in next section. However, we believe that this starting point is much better than simplified parametrized tight-binding like s-band models. 

TB-LMTO tight binding-linear muffin tin orbitals ... 

Tab. 11.1. Tight-binding parameters obtained from the least-square-error fit to LMTO band dispersions for the nine ll-VI semiconductors in the sp d basis with the A-B and B-B interactions. The first row lists the interatomic spacings in A, the next eight rows contain the onsite energies for all the orbitals, e.g. the row for dc t2) lists the entries for the t2cl orbital onsite energies for the cation. The subscript a denotes the anion. The last fifteen rows list the Slater Koster parameters. The last column shows the average value of the Slater Koster parameters multiplied by the square of the cation-anion distance, d. ...

All the TB models discussed so far are based on the nearest neighbor interactions. Recently, Sapra et al. proposed [73] the sp d tight-binding model with cation-anion nearest neighbor and anion-anion next nearest neighbor (NNN) interactions for the A B semiconductor compounds with A = Zn, Cd, Hg and B = S, Se, Te. The model was chosen after a careful analysis of the bulk band structures of these compounds obtained from the linearized muffin tin orbital (LMTO) method as described earlier in this section. These calculations were car-... 

Fig. 8. Calculated surface energy for fcc(lll) surfaces of 3d and 4d metals (solid squares), compared with experiment (open circles) (Skriver and Rosengaard, 1992 tight-binding L.MTO-ASA, with Green function method). For the 3d metals, the dashed line connecting solid circles gives results from spin-polarized calculations. For the 4d metals, the dashed line connecting open triangles gives results from Methfessel et al. (1992 full potential LMTO, slab geometry).

Within density-functional theory, a linear combination of overlapping non-orthogonal orbitals from first principles may be utilized to arrive at at full-potential local orbital (FPLO) method [213], and this k-dependent LCAO approach comes close to full-potential APW-based methods (see Sections 2.15.3 and 2.15.4) in terms of numerical accuracy, although FPLO is much faster simply because of the locality of the basis set. Even faster, due to a strongly simplified potential, is a parameter-free (density-functional) tight-binding method called TB-LMTO-ASA, derived through localization of a delocalized basis set (see Section 2.15.4). 

SIC T TB-LMTO- ASA self-interaction correction transition metal tight-binding linear muifln-tin orbital atomic sphere approximation / magnetic susceptibility absolute electronegativity... 

By using the tight-binding linearized muffin-tin orbital method combined with die coherent-potential approximation (TB-LMTO-CPA) the total energies, bulk moduli, equilibrium lattice parameters, magnetie moments, and hyperfine fields of bcc solid solution were ealeulated by [2000San], and are in qualitative agreement with experimental trends. 

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