Nature of Mott transition in a hydrogen lattice

Mott transition, an electron correlation induced metal-insulator transition, has long been realized in many materials. Yet, the microscopic nature of the transition proposed by Mott has not been carefully examined in these materials, even by modern theories. This is because Mott's original proposal makes use of non-linear change of screening of long-range Coulomb interaction that are almost always ignored in simple models used in previous study of Mott transition. Here we study the Mott transition of an artificial hydrogen lattice including both the long-range Coulomb interaction and the strong on-site correlation, via an dynamical mean-field extension of density functional calculation. We found that in the relevant range of lattice spacing, the system is in the charge-transfer regime, namely the charge fluctuation involves mostly higher energy orbitals beyond 1s one, rendering a single-band Hubbard model inadequate. Interestingly, Mott transition occurs when atomic bound states are still present. Our study challenges Mott's original microscopic picture and reveal some key physics of metal-insulator transition in realistic materials.