Velocity renormalization near the Mott transition in a perfectly ordered lattice

In the Lindhard theory for an unscreened electron gas the velocity is renormalized by the electron-electron interactions and actually diverges logarithmically at the Fermi surface. Normally, in 3D systems screening reduces this renormalization to about 5%. We suggest that in quasi-2D systems near the Mott transitions, screening is less effective and consequently the velocity at the FS is increased significantly by the nenormalization. This increase is associated with a decrease in the single-particle density of states, which reduces the screening further, enhancing this effect. This model applies to a highly ordered layered crystal, where k (in the plane) is a good quantum number.