Momentum distribution of itinerant electrons in the one-dimensional Falicov-Kimball model

The momentum distribution n(k) of itinerant electrons in the one-dimensional Falicov-Kimball model is calculated for various ground-state phases. In particular, we examine the periodic phases with period two, three and four (that are ground-states for all Coulomb interactions) as well as the phase separated states (that are ground states for small Coulomb interactions). For all periodic phases examined the momentum distribution is a smooth function of k with no sign of any discontinuity or singular behavior at the Fermi surface k = k(F). An unusual behavior of n(k) (a local maximum) is found at k = 3k(F) for electron concentrations outside half-filling. For the phase separated ground states the momentum distribution n(k) exhibits discontinuity at k = k(0) < k(F). This behavior is interpreted in terms of a Fermi liquid.