Photoemission Spectra from Reduced Density Matrices: the Band Gap in Strongly Correlated Systems

Abstract

We present a method for the calculation of photoemission spectra in terms of reduced density matrices. We start from the spectral representation of the one-body Green's function G, whose imaginary part is related to photoemission spectra, and we introduce a frequency-dependent effective energy that accounts for all the poles of G. Simple approximations to this effective energy give accurate spectra in model systems in the weak as well as strong correlation regime. In real systems reduced density matrices can be obtained from reduced density-matrix functional theory. Here we use this approach to calculate the photoemission spectrum of bulk NiO: our method yields a qualitatively correct picture both in the antiferromagnetic and paramagnetic phases, contrary to mean-field methods, in which the paramagnet is a metal.

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• Unphysical Discontinuities in GW Methods
• Potential energy surfaces without unphysical discontinuities: the Coulomb-hole plus screened exchange approach
• Scrutinizing $GW$-based methods using the Hubbard dimer
• Introducing screening in one-body density matrix functionals: impact on the Extended Koopmans' Theorem's charged excitations of model systems
• Can $GW$ Handle Multireference Systems?
• Screened extended Koopmans' theorem: photoemission at weak and strong correlation
• Photoemission spectrum in paramagnetic FeO under pressure: towards an \textit{ab-initio} description
• Adaptive cluster approximation for reduced density-matrix functional theory
• Structure of the first order Reduced Density Matrix in three electron systems: A Generalized Pauli Constraints assisted study
• Parquet theory for molecular systems: Formalism and static kernel parquet approximation
• Broken symmetry solutions in one-dimensional lattice models via many-body perturbation theory