Cluster calculations using muffin-tin orbitals

Abstract

The linear combination of muffin-tin orbitals (LMTO) method, developed by Andersen (see Phys. Rev. B, vol.12, p.3060 (1975)) and applied previously to the electronic properties of bulk materials, has been used to calculate energy eigenvalues and charge distributions for small clusters of atoms. For a muffin-tin potential (spherically symmetrical within touching spheres surrounding the atoms, constant between them), the method reproduces accurately the results of multiple-scattering (KKR) calculations. The LMTO method has, however, several marked advantages: (1) computational times are much less; (2) false roots of the secular matrix do not occur; (3) improved convergence of eigenfunctions and energies can readily be obtained. These points are examined in detail for the clusters C₂, Al₅Na and Al₅O.