Role of screening and charge transfer for a Mott transition in a Hydrogen lattice

A lattice of hydrogenic atoms may be regarded as a prototypical model system displaying a Mott metal-insulator transition as the density is varied at zero temperature. According to early ideas of Mott, however, this transition may be accompanied by appreciable charge transfer from the hydrogenic impurity band to the conduction band, giving rise to a significant screening of the ionic binding potential, possibly leading to a first order Mott transition at T=0. Based on very recent ab-initio modeling [1] of the hydrogenic lattice, we here propose a minimal model system to investigate the relevant screening effects, which are usually ignored in standard single-band Hubbard model description of the Mott transition. We investigate the appropriate (two band) charge-transfer model, supplemented by an inter-band Coulomb interaction, which is solved using a combination of slave-boson (Gutzwiller) methods and DMFT. The results should have strong relevance for the long-standing puzzle of the metal-insulator transition in doped semiconductors, such as Si:P.
[1] S. Sen, Y. Yao, N. Lanata, W. Ku, and V. Dobrosavljevic (2017, unpublished).