Fate of the Mott Metal–Insulator Transition in the 2D Hubbard Model: A Large-Cluster DCA Study

The Mott metal–insulator transition is a central problem in the physics of strongly correlated materials, attracting renewed attention with the development of advanced numerical methods that treat correlation effects beyond mean-field approximations. Despite extensive progress, a systematic understanding of how nonlocal correlations and geometric frustration influence the Mott transition and its nature in two dimensions remains incomplete. We present a systematic large-cluster dynamical cluster approximation (DCA) study of the Mott transition in the two-dimensional Hubbard model. By extending simulations to larger clusters and lower temperatures, we quantify how nonlocal correlations reshape the phase boundary and modify the critical interaction strength and critical temperature. Furthermore, we show that introducing geometric frustration stabilizes the metallic phase and smooths the transition, in line with experimental observations in quasi-2D correlated materials. Our results demonstrate that the interplay between frustration and nonlocal correlations plays a decisive role in determining the character and stability of the Mott transition in realistic two-dimensional systems.