Existence of a ferroelectric ground state with a spontaneous polarization in the Falicov-Kimball model

The extrapolation of small-cluster exact-diagonalization calculations is used to examine the possibility of electronic ferroelectricity in the one-dimensional spinless and spin-one-half Falicov-Kimball model (FKM). It is found that neither the spinless nor the spin-one-half version of the FKM allows for a ferroelectric ground state with a spontaneous polarization, i.e., there is no nonvanishing 〈d⁺f〉 expectation value for vanishing hybridization V.