Muffin-tin orbitals and the total energy of atomic clusters

The Hohenberg-Kohn-Sham (HKS) density-functional equations are solved for clusters of atoms using the linear muffin-tin orbital method (LMTO) of Andersen. The approach is numerically efficient and the self-consistency condition applies to the full potential. Binding energies, equilibrium separations, vibration frequencies, and dipole moments calculated for a series of first-row diatomic molecules agree well with experiment, indicating that the HKS scheme gives a quantitative description of the energy and electron-density changes associated with chemical bonding. The ability of the LMTO method to treat non-muffin-tin potential terms and its energy-independent partial-wave basis make it ideally suited for application to larger systems.