SKM 2023 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 14: Development of Computational Methods: Thermodynamics and Local Chemistry, Electronic Structure

MM 14.9: Talk

Tuesday, March 28, 2023, 12:30–12:45, SCH A 251

Multi-orbital models within the ghost Gutzwiller approximation — •Carlos Mejuto-Zaera and Michele Fabrizio — SISSA, Trieste, Italy

In the pursuit towards targeted material design leveraging strong electronic correlation, computationally inexpensive yet qualitatively reliable methods play a fundamental role. These approaches should allow for a rapid mapping of phase space, unveiling a first impression of possible phases of matter, which can then be explored in selected regions of parameter space with more accurate yet involved techniques. Recently, the ghost Gutzwiller Approximation (gGA) has been shown to be an interesting candidate for this kind of phenomenological search. Based on a self-consistency condition for the simple one-body reduced density matrix of a discretized impurity model, this method can capture spectral features of both coherent and incoherent nature in the one-body Green's function. In this work we extend its applicability to the multi-orbital regime employing a truncated solver based on selected configuration interaction. This allows for increasing the number of correlated orbitals while keeping the size ratio of bath to impurity constant. We explore the reliability of the gGA for describing the phase diagram of multi-band models, comparing to more sophisticated embedding methods. We shall assess the potential of gGA for modelling of complex materials, possibly in combination with ab-initio methods.