Tight-binding linear muffin-tin orbital

B. Wenzien J. Kudrnovsky, V. Drchal and M. Sob, On the calculation of the surface Green s function by the tight-binding linear-muffin tin orbital method, J. Phys. Condens. Matter 1, 9893 (1989). 

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

Figure 5 Total (per unit cell) and local (per space-filling atomic spheres of equal size at both Pt and Sn sites) densities of states of PtsSn, calculated by the tight-binding linear muffin-tin orbitals method. At positive (sample-) bias voltages the unoccupied states above E are imaged in the STM. From Ref. [27].

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. 

O.K. Andersen, Z. Pawlowska, and O. Jepsen, Illustration of the linear-muffin-tin-orbital tight-binding representation Compact orbitals and charge density in Si, Phys. Rev. B 34 5253 (1986). 

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. 

Electronic structure methods for studies of nanostructures can be divided broadly into supercell methods and real-space methods. Supercell methods use standard k-space electronic structure techniques separating periodically repeated nanostructures by distances large enough to neglect their interactions. Direct space methods do not need to use periodic boundary conditions. Various electronic structure methods are developed and applied using both approaches. In this section we will shortly discuss few popular but powerful electronic structure methods the pseudopotential method, linear muffin-tin orbital and related methods, and tight-binding methods. 

Early theoretical studies based on a semi-empirical self-consistent tight-binding scheme indicate that the core-level shifts in the Pd/W(l 10) and PtAV(l 10) systems come from initial state effects (d-s,p rehybridisation, for example) [37]. The calculated shift for the Pd core level was 0.7 eV versus the value of 0.8 eV measured experimentally [53]. More sophisticated calculations (fiill-potential linear muffin-tin orbital method with LDF) for the Pd/Mo(110) system also indicate that the Pd 3d core-level shifts reflect initial state effects (substantial polarization of electrons around Pd) [40]. In this case, the calculated Pd 3ds/2 core level (0.9 eV) is identical to the experimental value and most of it (0.77 eV) comes from initial state effects while the rest (0.13 eV) originates in changes in the screening of the core hole [40]. 

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-... 

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