Relevance of long-range screening in Mott transition examined via a hydrogen lattice

TL;DR

This study investigates the role of long-range screening in the Mott transition using a hydrogen lattice model and finds that local interactions dominate, making long-range screening effects negligible in this context.

Contribution

The paper demonstrates that long-range screening does not significantly influence the Mott transition in a hydrogen lattice, challenging previous assumptions about its importance.

Findings

Long-range screening has minimal impact on the Mott transition in the model.

The transition is driven by local interactions and charge-transfer gap closure.

The insulating phase is primarily due to strong local interactions, not long-range effects.

Abstract

The Mott transition, a metal-insulator transition due to strong electronic interaction, is observed in many materials without an accompanying change of system symmetry. An important open question in Mott's proposal is the role of long-range screening, whose drastic change across the quantum phase transition may self-consistently make the transition more abrupt, toward a first-order one. Here we investigate this effect in a model system of hydrogen atoms in a cubic lattice, using charge self-consistent dynamical mean-field theory that incorporates approximately the long-range interaction within the density functional treatment. We found that the system is well within the charge-transfer regime and that the charge-transfer gap intimately related to the Mott transition closes smoothly instead. This indicates that the long-range screening does not play an essential role in this prototypical example. This finding can be understood from the fact that the obtained insulating phase in this model system is driven by strong local interaction, and the transition is associated with the closing of charge-transfer gap. Contrary to Mott's length scale argument, such energetic competition between kinetic energy and local interaction is thus insensitive to long-range screening.