EMTO: Exact Muffin-Tin Orbitals
Definition:An efficient approach to describe the electronic wave function of a crystal structure in terms of orbitals localized at atomic positions.
Explanation:The EMTO method is a density functional theory (→DFT) method which is used to solve the one electron Schrödinger equations within unit cells defined around the lattice sites. These unit cells are chosen to be the Wigner–Seitz (WS) cells. The cell for a given center is constructed by bisecting with a plane each line which connects the actual site with another site, and taking the closed region around the lattice site which is bounded by these planes. The atomic potential appearing in the Schrödinger equations is approximated by the optimized overlapping muffin-tin (MT) spherical wells each of which is centered on a lattice site and can spread beyond the boundary of the actual WS-cell [1]. This is in contrast to other MT methods where the potential MT-spheres are not overlapped. The fact that individual MT potentials are allowed to overlap makes the EMTO method similar in precision to full potential methods. The combination of EMTO method with the coherent potential approximation (→CPA) enables to investigate substitutionally disordered alloys.
References:[1] L. Vitos. Computational Quantum Mechanics for Materials Engineers: The EMTO Method and Applications. Engineering Materials and Processes, Springer London (2007)