We study the Mott transition as a function of interaction strength in the half-filled Hubbard chain with next-nearest-neighbor hopping $t^{\prime }$ by calculating the response to an external electric field using the density matrix renormalization group. The electric susceptibility $\chi$ diverges when approaching the critical point from the insulating side. We show that the correlation length $\xi$ characterizing this transition is directly proportional to fluctuations of the polarization and that $\chi \sim {\xi }^2$. The critical behavior shows that the transition is infinite order for all $t^{\prime }$, whether or not a spin gap is present, and that hyperscaling holds.

• Received 20 June 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.468