  The Gutzwiller wave function for a strongly correlated model can, if
supplemented with a long-range Jastrow factor, provide a proper variational
description of Mott insulators, so far unavailable. We demonstrate this concept
in the prototypical one-dimensional $t-t^\prime$ Hubbard model, where at half
filling we reproduce all known phases, namely the ordinary Mott undimerized
insulator with power-law spin correlations at small $t^\prime/t$, the
spin-gapped metal above a critical $t^\prime/t$ and small $U$, and the
dimerized Mott insulator at large repulsion.
