Tight-binding model and effective Hamiltonian for twodimensional materials.

A wide range of two-dimensional (2D) materials ranging from graphene to topological insulators share the extraordinary phenomenon that electrons behave as relativistic particles in their low-energy excitations in different formats such as Dirac cones, Dirac nodal lines and Weyl nodes and so on. These emergent behaviors of fermions in condensed matter systems have attracted both experimental and theoretical researches. Density functional theory is a good point to start calculating the electronic properties of materials, but this method is unable to find all properties of the system. One of the most important methods to calculate the electronic properties of such systems is the Green's function approach. In this method the tight-binding (TB) model explains the physical system. Therefore we need to define a TB model and find the hopping coefficients between atoms and orbitals. With the linear combination of atomic orbitals (LCAO) method the system can be described by a set of non-interacting single-particles. By using the simplified LCAO method in combination with firstprinciples calculations, we are able to construct TB models in the two-centre approximation for 2D materials. The Slater and Koster (SK) approach is a powerful method to reproduce the first-principles data and construct the TB model. This method is applied to calculate the TB Hamiltonian of these systems based on the s, p and d orbitals. We obtain expressions for the Hamiltonian and overlap matrix elements between different orbitals for the different atoms and present the SK coefficients in a nonorthogonal basis set.

Keywords:2D MATERIALS, ELECTRONIC STRUCTURE

Disciplines:Condensed matter physics and nanophysics not elsewhere classified

Project type:Collaboration project