(Non-) orthogonal Tight Binding method

In order to model efficient the electronic structure of a material, CaHmd uses the Tight Binding approach. Here, the propagation of the electrons is represented by hopping energies and local on-site energies (potentials). The hopping are further parameterized in terms of the Slater-Koster parametrization 1 were the parameters are represented in a polynomial anasatz motivated by Mehl and Papaconstantopoulos 2

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Fig. 1 - Schematic representation of hopping
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Fig. 2 - Schematic representation of hopping

The tight binding code offers functionalities to calculate the following quantities

Electron band stracture/spectral function and density of states
Surface and interface spectral function
Non-local Gilbert damping tensor
Moment of inertia tensor
Alloy properties in the coherent potential approximation
Conductivity tensor
Berry curvature
Magnetic exchange parameters
Heisenberg exchange, Dzyaloshinskii-Moriya interaction, magneto-crystaline anisotropy, four-spin exchange (biquadratic exchange, ring-exchange)
Interatomic forces and atomic magnetic fields
Contrained fields
Ab-initio magnetization-lattice dynamics
Occupation dynamics

Fitting of Slater-Koster parameter

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Fig. 3 - Fitting of non spin-polarized KKR bands (red dots) with tight binding bands (blue dotes) using Genetic algorithms.

  1. Physical Review. 94 (1954) 1498–1524 DOI ↩︎

  2. J. Phys.: Condens. Matter 15 (2003) R413–R440 ↩︎