Slater-Koster Parameters Research Articles

Spectroscopy of La0.5Sr1.5MnO4 orbital ordering: a cluster many-body calculation

We have studied the orbital ordering (OO) in La0.5Sr1.5MnO4 and its soft x-ray resonant diffraction spectroscopic signature at the Mn L2, L3 edges. We have modelled the system in second quantization as a small planar cluster consisting of a central Mn atom, with the first neighbouring shells of oxygen and Mn atoms. For the effective Hamiltonian we consider Slater-Koster parameters, charge transfer and electron correlation energies obtained from previous measurements on manganites. We calculate the OO as a function of oxygen distortion and spin correlation used as adjustable parameters. Their contribution as a function of temperature is clearly distinguished with a good spectroscopic agreement.

Tight-binding study of thermal expansions for Mo3Si

We implemented a tight-binding parameter extraction scheme that is suitable for the modeling of intermetallic alloy systems. Using Mo3Si as an example, we obtained the Slater-Koster tight-binding parameters directly from results of full-potential linear muffin-tin orbital calculation by using a modification of the approach of McMahan and Klepeis [Phys. Rev. B 56, 12250 (1997)]. The transferability and accuracy of these parameters were tested against ab initio results. Augmented by a fitted repulsive energy contribution that takes the form of embedded atom potential, the tight-binding total energy method was applied in Monte Carlo simulations to compute the coefficients of thermal expansion for Mo3Si.

Automatic generation of matrix element derivatives for tight binding models

Tight binding (TB) models are one approach to the quantum mechanical many particle problem. An important role in TB models is played by hopping and overlap matrix elements between the orbitals on two atoms, which of course depend on the relative positions of the atoms involved. This dependence can be expressed with the help of Slater-Koster parameters, which are usually taken from tables. Recently, a way to generate these tables automatically was published. If TB approaches are applied to simulations of the dynamics of a system, also derivatives of matrix elements can appear. In this work we give general expressions for first and second derivatives of such matrix elements. Implemented in a computer program they obviate the need to type all the required derivatives of all occuring matrix elements by hand.

Oscillation of Conductance in Molecular Junctions of Carbon Ladder Compounds

The electrical conductances of dithiolates of polyacene (PA(n)DTs) and polyphenanthrene (PPh(n)DTs), which are typical carbon ladder compounds, are calculated by means of the Landauer formulation combined with density functional theory, where n is the number of benzene rings involved. Surface Green function used in the Landauer formulation is calculated with the Slater-Koster parameters. Attention is turned to the wire-length dependence of the conductances of PA(n)DTs and PPh(n)DTs. The damping of conductance of PA(n)DTs is much smaller than that of PPh(n)DTs because of the small HOMO-LUMO gaps of PA(n)DTs. PA(n)DTs are thus good molecular wires for nanosized electronic devices. Conductance oscillation is found for both molecular wires when n is less than 7. The electrical conductance is enhanced in PA(n)DTs with even-numbered benzene rings, whereas it is enhanced in PPh(n)DTs with odd-numbered benzene rings. The observed conductance oscillation of PA(n)DTs and PPh(n)DTs is due to the oscillation of orbital energy and electron population. Other pi-conjugated oligomers (polyacetylene-DT, oligo(thiophene)-DT, oligo(meso-meso-linked zinc(II) porphyrin-butadiynylene)-DT, oligo(p-phenylethynylene)-DT, and oligo(p-phenylene)-DT) are also studied. In contrast to PA(n)DTs and PPh(n)DTs, the five molecular wires show ordinary exponential decays of conductance.

Experimental tight-binding parameterization of the oxygen-metal interaction: application to the Rh(1 1 0)(2 × 2) p2mg-O surface

The Rh(1 1 0)(2 × 2) p2mg-O surface has been studied by ARUPS utilizing linearly polarized HeI and synchrotron radiations. To make an electronic band structure map of the O2p states, p-polarized 100 eV synchrotron radiation is used. This photon energy is selected as the Cooper minimum of the Rh4d states to give a relatively higher cross-section of O2p state. Apart from this, tight-binding calculations of this system is made, in which Rh4d, 5s, 5p and O2p states are included as the basis set, and the Slater–Koster parameters of Rh–O interaction are used as fitting parameters. With these calculations, the experimentally obtained electronic structure of the Rh(1 1 0)(2 × 2) p2mg-O surface is successfully interpreted.

Electronic structure of theCu−O/Ag(110)(2×2)p2mgsurface

Reviewing the Slater-Koster parameters experimentally collected on various oxygen-adsorbed surfaces, we suggest a scaling law describing the Slater-Koster (SK) parameters between the oxygen and d-electron metals, instead of the conventional Harrison rule. We demonstrate an examination of this scaling law by the comparative study with the angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) measurement on the $\mathrm{Cu}\ensuremath{-}\mathrm{O}/\mathrm{Ag}(110)(2\ifmmode\times\else\texttimes\fi{}2)p2mg$ surface. First, the electronic structure of the $\mathrm{Cu}\ensuremath{-}\mathrm{O}/\mathrm{Ag}(110)(2\ifmmode\times\else\texttimes\fi{}2)p2mg$ surface is determined by ARUPS using synchrotron radiation. The band assignment of O2p and $\mathrm{Cu}3d$ is carefully done by means of the cross-section analysis for the 20 and 100 eV photon energy. The obtained electronic structure is interpreted in terms of the tight-binding calculation. In the calculation, we use SK parameters produced by the new scaling law. From the good agreement between the experiment and the calculation, we can see that the scaling law is practically useful.

Transferable tight-binding parametrization for the group-III nitrides

We present accurate tight-binding (TB) parametrizations of the quasi-particle band structures of AlN, GaN, and InN, both for the zincblende and wurtzite phases. For this purpose, an empirical sp3d5s* nearest-neighbor TB model including the spin–orbit interaction is used, ensuring the transferability of the Slater–Koster parameters to changes in the structural environment. The present approach results in excellent agreement with experimental band positions and ab initio calculations for the lowest conduction band and the valence-band splittings. As a first application, we investigate the electronic band structure of an ordered Al0.5Ga0.5N alloy in the wurtzite phase.

Precise tight-binding description of the band structure ofMgB2

We present a careful recasting of first-principles band structure calculations for MgB2 in a non-orthogonal sp-tight-binding (TB) basis. Our TB results almost exactly reproduce our full potential linearized augmented plane wave results for the energy bands, the densities of states and the total energies. Our procedure generates transferable Slater-Koster parameters which should be useful for other studies of this important material.

Tight-binding Hamiltonians for superconducting YBa 2Cu 3O 7

It is found that the Slater–Koster parameters for YBa 2Cu 3O 7 determined by De Weert et al. (M.J. De Weert, D.A. Papaconstantapoulos, W.E. Pickett, Phys. Rev. B, 39 (1989) 4235) do not give correct wavefunctions to each eigenstate. In this context, accurate tight-binding parametrization of first-principles band structures are newly performed so as to reproduce both the numerically calculated energy bands and wavefunctions of YBa 2Cu 3O 7 correctly.

Force constants for substitutional alloys

Recently, the importance of the vibrational aspects of alloy phase stability has attracted much interest. There is much controversy over the extent to which the vibrational free energy affects order-disorder temperatures and other phase equilibria. Here, we examine the feasibility of defining transferable force constants for an alloy in much the same spirit as tight-binding Slater-Koster parameters can be defined for substitutional alloys. In particular, the predictive ability of such alloy specific, but configuration independent, force constants for the elastic, relaxation, and vibrational properties is examined.

Direct calculation of Slater-Koster parameters: Fourfold-coordinated silicon/boron phases

The need for tight-binding total-energy representations of interatomic forces has renewed interest in Slater-Koster parametrization of electron band structure. For larger numbers of parameters, as in multicomponent systems, and to truly test issues of transferability, it is advantageous to have means of directly calculating these parameters. Here we derive analytic expressions for the two-center Slater-Koster hopping parameters, effective site energies, and effective crystal-field parameters in terms of the one-electron Hamiltonian matrix elements in any localized minimal basis, and analogous quantities for the overlap. We apply these expressions to the cubic diamond phases of Si and B, and the zinc-blende phase of SiB at three volumes each, using $\mathrm{spd}$, nonorthogonal full potential linear muffin-tin orbital matrix elements calculated with a linked or contracted minimal basis.

Excitons in solid argon

A model for consistently describing the entire Ar exciton series is presented. Making use of a reliable approximation of the band structure in the whole first Brillouin zone, as provided by appropriately chosen Slater–Koster parameters, is an essential part of our approach. Its dominating effect on the final results is demonstrated by performing comparative studies based on several simpler band models. In fact, the energy defect of the n=1 exciton can to a large extent be understood as a consequence of the large-k variation of the bands. Our model, furthermore, makes allowance for the spin–orbit coupling of the valence bands, the exchange interaction and the dielectric function of the electron-hole potential. Without using any free parameter, the calculated Ar exciton series is in excellent agreement with the experimental binding energies.

Tight-binding calculation of ionization potentials of small silicon clusters

The size dependence of ionization potentials (IPs) of silicon clusters is studied using a localized orbital theory on the basis of the tight-binding approximation. The geometric structures of the silicon clusters are from the theoretical results of the force field model, and the hopping integral and overlap integral in the tight-binding Hamiltonian matrix are obtained from the best fitted formula for the Slater-Koster parameters. It has been found that our results conform to experiments much better than the previous LDA calculation and the estimation of the spherical droplet model. The local maximum of the IPs for Si 10 is obtained, corresponding to the magic number behaviour observed by other experimental means. The structural isomer effect and relaxation effect on the IPs of the silicon clusters are also discussed.

Using diatomics-in-molecules in calculating semiempirical band structures

The diatomics-in-molecules approach usually limited to small-sized molecules is applied to infinitely extended systems, thereby relating the empirical potentials used as DIM input data to the well-known Slater-Koster parameters of tight-binding theory. Based on this parameters the band structure and the density of states of the rare-gas (RG) valence bands are calculated. Our results are in very good agreement with experimental data like the width of the bands and the vacuum-energy. Moreover, the characteristic features of the calculated density of states reflect the spectroscopically determined peak positions satisfactorily. We discuss further applications of this work.

A theoretical study of the (2*1) reconstruction of Si(100): application to surface-induced core level shifts

The tight-binding method is used to study the (2*1) reconstruction of the Si(100) surface. The laws of variation with interatomic distance of the Slater-Koster parameters and of the pairwise repulsion energy are defined in order to give a good description of the electronic band structure and of the elastic properties of bulk silicon. The necessity of taking into account, during the total energy minimization, the surface-induced atomic level shifts is emphasized. The dimer bond length is shown to be in good agreement with experimental values. Then, the atomic level shifts are related to the surface-induced core level shifts. A new interpretation of core level photoemission spectra, consistent with a weak asymmetry of the dimers, is finally proposed.

Hall coefficient of cubic metals.

A systematic study of the low-field Hall coefficient ${\mathit{R}}_{\mathit{H}}$ of 23 cubic metals is done using tabulated Slater-Koster parameters for the band structure and a tetrahedron method to calculate the Fermi-surface integrals. In the approximation of an isotropic relaxation time, the Hall coefficient depends only on the Fermi-surface topology. The effect of the band structure is reflected in deviations of ${\mathit{R}}_{\mathit{H}}$ from the free-electron values -1/ne. In favorable cases, our calculations agree to \ensuremath{\approxeq}\ifmmode\pm\else\textpm\fi{}10% with experimental data. Some of the deviations can be traced back to inaccurate band structures, e.g., in Cs or to rapidly changing ${\mathit{R}}_{\mathit{H}}$ with ${\mathrm{\ensuremath{\varepsilon}}}_{\mathit{F}}$ leading to problems with convergence, e.g., in Pt. Discrepancies with experiment show the need for an anisotropic relaxation time, especially in Pd where small regions of high curvature dominate the Hall coefficient and in Al where two bands cross the Fermi surface. The similarity in the band structures of Rh, Pd, and Ag encourages the use of a rigid-band model, which agrees qualitatively with the experimental Hall coefficients for the alloys Rh-Pd and Pd-Ag.

Theoretical Investigation of Phase Stability in Non-Magnetic Fe-V Substitutional Alloys

The assessed phase diagram of Fe-V exhibits a continuous high temperature bcc solid solution intersected at lower temperatures by a complex sigma phase centered around equiatomic composition [1]. Slow kinetics of the bcc to sigma transformation make it possible to retain the bcc solid solution at low temperature. It has been observed that this metastable solid solution has a tendency to order with a CsCl type structure (B2) below 970 K [1,2]. As a first attempt to describe this behavior from an electronic structure approach, this paper will study the phase stability on the bcc lattice using a realistic tight-binding Hamiltonian. Details of the tight-binding description have been given elsewhere [3]. Main features are as follows: Element and structure specific Slater-Koster parameters are used [4] and lattice parameter effects are incorporated through scaling [5]. Charge transfer is set to zero by rigidly shifting the onsite energies of one constituent. The Coherent Potential Approximation (CPA) is invoked with four levels corresponding to states with s, p, t2g and eg like symmetry. Effects of off-diagonal disorder (ODD) have not been included, instead, an average alloy Hamiltonian was defined using the Slater-Koster parameters of the components weighted by concentration. At equiatomic composition the effect of this approximation has been evaluated by repeating the electronic structure calculation with inclusion of ODD effects (see also [6]). Effective pair interactions, as defined within the Generalized Perturbation Method (GPM) [7], have been computed and have been used to evaluate the ground states of configurational order on the bcc lattice in the Fe-V system. Furthermore, the theoretically derived energetic properties have been used to determine the phase diagram pertaining to the (metastable) bcc lattice with the Cluster Variation Method (CVM) [8] in the tetrahedron approximation

Band structure and electronic properties of native defects in cubic SiC.

A set of semiempirical expressions for the two-center integrals which show the explicit dependence of these quantities on the atomic characteristics, on the dielectric constant, on the ionicity of the solid, and also on the interatomic separations is constructed for silicon carbide. These integrals enter the Slater-Koster parameters representing the Hamiltonian matrix elements in the tight-binding method of calculating the electronic band structure of the semiconductors. A large-cluster recursion method is then used to determine the local density of states associated with each orbital at a given atomic site and also to study the electronic states associated with native defects in SiC.

Tight-binding coherent-potential-approximation study of the electronic states of palladium-noble-metal alloys.

We have performed calculations of the electronic states of palladium--noble-metal disordered alloys using an improved version of the tight-binding coherent-potential-approximation (TB-CPA) formalism. Our results for Pd-Ag are in excellent agreement with both experiment and the Korringa-Kohn-Rostoker (KKR) CPA. For Pd-Au we also obtain good agreement with specific-heat measurements. For Pd-Cu, probably due to charge-transfer effects, we do not obtain satisfactory agreement with experiment at the Cu-rich end. Our calculations indicate that if (a) highly accurate Slater-Koster parameters are used and (b) all the orbitals are included in the CPA conditions (i.e., not using a one-level TB model), the TB-CPA gives results that are equivalent to those of the KRR-CPA except in cases where off-diagonal disorder might be important.

Transferability and scaling of Slater-Koster parameters in transition metals.

We present a study of the following aspects of the Slater-Koster method in transition metals: (a) A quantitative analysis of the band structures resulting from Harrison's solid-state table. (b) An evaluation of the Andersen-Harrison scaling laws for obtaining tight-binding parameters at different lattice constants. (c) An examination of the transferability of Slater-Koster parameters from elements to compounds.