| The density matrix embedding theory (DMET) is a novel numerical technique designed for a multi-level treatment of electronic systems. In particular, it allows for approximately disentangling a strongly correlated impurity region from an environment treated at the mean-field level. DMET has significant advantages over other approaches with similar scope: It is in practice much simpler than dynamical mean field theory (DMFT), and does not involve frequency dependent intermediates. Compared to density functional theory (DFT) embedding, DMET can easily break through covalent bonds, and is free of ill-conditioned optimized effective potential fitting problems. We demonstrate our approach with data on the one- and two-dimensional Hubbard models, and with first applications to molecules and solids employing the full ab initio Hamiltonian. |
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