Site-occupation embedding theory (SOET) [1] is a density-functional theory (DFT)-based method which aims at modelling strongly correlated electrons. It is in principle exact and applicable to model and quantum chemical Hamiltonians. The theory will be presented for the Hubbard Hamiltonian. In contrast to conventional DFT approaches, the site (or orbital) occupations are deduced in SOET from a partially-interacting system consisting of one (or more) impurity site(s) and non-interacting bath sites. The correlation energy of the bath is then treated implicitly by means of a site-occupation functional. In this presentation, I will discuss a simple impurity-occupation functional approximation based on the two-level (2L) Hubbard model which is referred to as two-level impurity local density approximation (2L-ILDA) [2]. Promising results obtained on a prototypical uniform 8-site Hubbard ring will be shown. If time permits, the extension of SOET to quantum chemical Hamiltonians [3] will also be discussed.
[1] E. Fromager, Mol. Phys. 113, 419 (2015)
[2] B. Senjean, M. Tsuchiizu, V. Robert, and E. Fromager, submitted to Mol. Phys. (2016), arXiv preprint arXiv:1602.02547
[3] B. Senjean and E. Fromager, in preparation (2016).