Reliability of Pseudopotential Charge Densities

An analysis of the charge-density and energy-level separations for the ${\mathrm{Si}}_2$ molecule is made using local semiempirical and nonlocal first-principles pseudopotentials. The results are compared with Hartree-Fock-Slater all-electron calculations. It is demonstrated that pseudopotential calculations for molecules are reliable, and that recent objections based on charge-density topology are unwarranted.