Charge conserving approximation for excitation properties of crystalline materials

Abstract

A charge conserving approximation scheme determining the excitations of crystalline solids is proposed. Like other such approximations, it relies on "downfolding" of the original microscopic model to a simpler electronic model on the lattice with pairwise interactions. A systematic truncation of the set of Dyson - Schwinger equations for correlators of the low energy (downfolded) model of a material, supplemented by a "covariant" calculation of correlators lead to a converging series of approximates. The covariance preserves all the Ward identities among correlators describing various condensed matter probes. It is shown that the third order approximant of this kind beyond classical and gaussian (Hartree - Fock) is precise enough and due to several fortunate features the complexity of calculation is surprisingly low so that a realistic material computation is feasible. Focus here is on the electron field correlator describing the electron (hole) excitations measured in photoemission and other probes. The scheme is tested on several solvable benchmark models

25 pages, 9 figures

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Cited by in corpus (4)

• Unified intermediate coupling description of the pseudogap and the strange metal phases of cuprates
• Modified $GW$ Method in Electronic Systems
• Mean field theory of short range order in strongly correlated low dimensional electronic systems
• Covariant Bethe-Salpeter approximation in strongly correlated electron systems model