  Ground-state properties of the non-interacting symmetric single-impurity
Anderson model (SIAM) are derived from the corresponding eigenenergy equation.
Explicit formulae are given for the ground-state energy, the hybridization, and
the momentum distribution that are essential quantities for variational
approaches to the interacting model. Various spectral functions, e.g., the
total density of states, the phase shift function, and the impurity spectral
function, are shown to agree with those obtained from the equation-of-motion
method (see supplementary material). For a constant hybridization strength and
a semi-elliptic host density of states it is seen that the impurity spectral
function builds up weight at the band edges.
