Multiplet structure and charge distributions in silicon and germanium dimers

Abstract

Calculations of binding-energy curves and charge distributions have been carried out for low-lying states of ${\mathrm{Si}}_{2}$ and ${\mathrm{Ge}}_{2}$ using the local-density-functional formalism. Calculated spectroscopic constants are in good agreement with experiment for the states of ${\mathrm{Si}}_{2}$ which have been identified, so that predictions for other states should be reliable. The binding-energy curves of the two dimers are remarkably similar, as are the $s\ensuremath{-}p$ valence orbitals of silicon and germanium atoms. Charge-density differences are similar to those calculated previously for ${\mathrm{C}}_{2}$ and orbital densities show pronounced differences from results of a recent pseudopotential calculation, even in regions far from the cores.