Equation of Motion Method for strongly correlated Fermi systems and Extended RPA approaches

Schuck, Peter; Delion, D. S.; Dukelsky, J.; Jemaï, M.; Литвинова, Елена; Roepke, G.; Tohyama, Mitsuru

doi:10.1016/j.physrep.2021.06.001

Cited by 24 publications

(9 citation statements)

References 194 publications

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“…Therefore, our next goal is to derive a general static approximation for the three-body self-energy. This could be achieved, for example, by using the equation of motion for G e+h 3 [38] along the same lines as has been done for G 1 or by using a similar strategy as in Ref. [27], where a practical scheme to calculate G 3 for the description of Auger spectra is proposed.…”

Section: Discussionmentioning

confidence: 99%

Photoemission spectral functions from the three-body Green's function

et al. 2022

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We present an original strategy for the calculation of direct and inverse photo-emission spectra from first principles. The main goal is to go beyond the standard Green's function approaches, such as the $GW$ method, in order to find a good description not only of the quasiparticles but also of the satellite structures, which are of particular importance in strongly correlated materials. To this end we use as a key quantity the three-body Green's function, or, more precisely, its hole-hole-electron and electron-electron-hole parts, and we show how the one-body Green's function, and hence the corresponding spectral function, can be retrieved from it. We show that, contrary to the one-body Green's function, information about satellites is already present in the non-interacting three-body Green's function. Therefore, simple approximations to the three-body self-energy, which is defined by the Dyson equation for the three-body Green's function and which contains many-body effects, can still yield accurate spectral functions. In particular, the self-energy can be chosen to be static which could simplify a self-consistent solution of the Dyson equation. We give a proof of principle of our strategy by applying it to the Hubbard dimer, for which the exact self-energy is available.

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Section: Discussionmentioning

confidence: 99%

Photoemission spectral functions from the three-body Green's function

et al. 2022

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“…A more self-consistent method to include this effect would be the so-called renormalized RPA (r-RPA) [41], where, in the particle-particle channel, the Pauli factor is replaced by…”

Section: B Effect Of the Quasiparticle Weightmentioning

confidence: 99%

BCS-BEC Crossover Effects and Pseudogap in Neutron Matter

Durel,

Urban

2020

Preprint

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Due to the large neutron-neutron scattering length, dilute neutron matter resembles the unitary Fermi gas, which lies half-way in the crossover from the BCS phase of weakly coupled Cooper pairs to the Bose-Einstein condensate of dimers. We discuss crossover effects in analogy with the T-matrix theory used in the physics of ultracold atoms, which we generalize to the case of a non-separable finite-range interaction. A problem of the standard Nozières-Schmitt-Rink approach and different ways to solve it are discussed. It is shown that in the strong-coupling regime, the spectral function exhibits a pseudo-gap at temperatures above the critical temperature Tc. The effect of the correlated density on the density dependence of Tc is found to be rather weak, but a possibly important effect due to the reduced quasiparticle weight is identified.

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“…The equation of motion (EOM) method builds a systematic framework for the description of many-body correlations, in particular, in strongly coupled fermionic systems [14][15][16][17][18][19]. Within this framework, the EOM's are generated for various time-dependent quantities, such as the correlation functions of field operators.…”

Section: Introductionmentioning

confidence: 99%

Nuclear Shell Structure in a Finite-Temperature Relativistic Framework

Wibowo¹,

Литвинова²

2021

Preprint

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The shell evolution of neutron-rich nuclei with temperature is studied in a beyond-mean-field framework rooted in the meson-nucleon Lagrangian. The temperature-dependent Dyson equation with the dynamical kernel taking into account the particle-vibration coupling (PVC) is solved for the fermionic propagators in the basis of the thermal relativistic mean-field Dirac spinors. The calculations are performed for 68−78 Ni in a broad range of temperatures 0 ≤ T ≤ 4 MeV. The special focus is put on the fragmentation pattern of the single-particle states, which is further investigated within toy models in strongly truncated model spaces. Such models allow for quantifying the sensitivity of the fragmentation to the phonon frequencies, the PVC strength and to the mean-field level density. The model studies provide insights into the temperature evolution of the PVC mechanism in real nuclear systems under the conditions which may occur in astrophysical environments.

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Equation of Motion Method for strongly correlated Fermi systems and Extended RPA approaches

Cited by 24 publications

References 194 publications

Photoemission spectral functions from the three-body Green's function

Photoemission spectral functions from the three-body Green's function

BCS-BEC Crossover Effects and Pseudogap in Neutron Matter

Nuclear Shell Structure in a Finite-Temperature Relativistic Framework

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