Cluster expansion for the self-energy: A simple many-body method for interpreting the photoemission spectra of correlated Fermi systems

1993 ◽  
Vol 48 (1) ◽  
pp. 418-425 ◽  
Author(s):  
Claudius Gros ◽  
Roser Valentí
Keyword(s):  
Cluster Expansion ◽  
The Self ◽  
Many Body ◽  
Fermi Systems ◽  
Self Energy ◽  
Body Method

scholarly journals Design of auxiliary systems for spectroscopy

2020 ◽  
Vol 224 ◽  
pp. 424-447
Author(s):  
Marco Vanzini ◽  
Francesco Sottile ◽  
Igor Reshetnyak ◽  
Sergio Ciuchi ◽  
Lucia Reining ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Density Functional ◽  
The Self ◽  
Many Body ◽  
Functional Theory ◽  
Correlation Kernel ◽  
Effective Potentials ◽  
Exchange Correlation ◽  
Self Energy ◽  
Many Body Perturbation Theory

In this contribution, we advocate the possibility of designing auxiliary systems with effective potentials or kernels that target only the specific spectral properties of interest and are simpler than the self-energy of many-body perturbation theory or the exchange–correlation kernel of time-dependent density-functional theory.

The Self Energy Approach for Calculation of Quasiparticle Energies in Materials Systems

1988 ◽  
Vol 141 ◽  
Author(s):  
Mark S. Hybertsen
Keyword(s):  
Energy Approach ◽  
The Self ◽  
Electron Interaction ◽  
Many Body ◽  
Self Energy ◽  
Short Period ◽  
Bulk Semiconductors ◽  
Spectroscopic Probes ◽  
Short Period Superlattices ◽  
The Many

AbstractA self energy approach directly taking into account the many-body nature of the electron-electron interaction is described which gives an excellent account of the quasiparticle band energies in semiconductors and insulators. The self energy approach provides a crucial link between structural models and spectroscopic probes of materials systems. Applications to bulk semiconductors, semiconductor surfaces and short period superlattices are described. A model for the screened Coulomb interaction can reduce the amount of computation required. Applicability of bulk self energy results to more complex systems, e.g. surfaces, is discussed.

An INDO MO Study on the Ground State and the Cationic States of Cyclopentadienyl Nickel Nitrosyl

1981 ◽  
Vol 36 (12) ◽  
pp. 1361-1366 ◽  
Author(s):  
Michael C. Böhm
Keyword(s):  
Perturbation Theory ◽  
Electronic Structure ◽  
Ground State ◽  
The Self ◽  
Many Body ◽  
Self Energy ◽  
Cyclopentadienyl Ligand ◽  
Energy Part ◽  
Correct Sequence ◽  
Many Body Perturbation Theory

The electronic structure of cyclopentadienyl nickel nitrosyl (1) in the ground state as well as the cationic states of 1 are investigated by means of a semiempirical INDO Hamiltonian and many body perturbation theory. It is demonstrated that the nature of the NiNO coupling is largely covalent while the interaction between the 3d center and the cyclopentadienyl ligand is predominantly of ionic type. The ground state MO sequence of the Ni 3d orbitals is 4e2(3dx²-y²/3dxy) below 7e1(3dXz/3dyz) and 15a1(3dz2). The sequence of the ionization potentials is 8e1 (Cp - π) < 15a1<4e2<7e1. The ionization energies have been determined by means of the Green’s function formalism; the self-energy part has been calculated by a second order and a renormalized approximation. Both procedures predict the correct sequence of ionization events.

scholarly journals Opacity from Loops in AdS

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Alexandria Costantino ◽  
Sylvain Fichet
Keyword(s):  
Imaginary Part ◽  
Quantum Dynamics ◽  
Model Building ◽  
Asymptotic Properties ◽  
The Self ◽  
Effective Theory ◽  
Self Energy ◽  
Higher Dimensional ◽  
Timelike Region ◽  
Spectral Representations

Abstract We investigate how quantum dynamics affects the propagation of a scalar field in Lorentzian AdS. We work in momentum space, in which the propagator admits two spectral representations (denoted “conformal” and “momentum”) in addition to a closed-form one, and all have a simple split structure. Focusing on scalar bubbles, we compute the imaginary part of the self-energy ImΠ in the three representations, which involves the evaluation of seemingly very different objects. We explicitly prove their equivalence in any dimension, and derive some elementary and asymptotic properties of ImΠ.Using a WKB-like approach in the timelike region, we evaluate the propagator dressed with the imaginary part of the self-energy. We find that the dressing from loops exponentially dampens the propagator when one of the endpoints is in the IR region, rendering this region opaque to propagation. This suppression may have implications for field-theoretical model-building in AdS. We argue that in the effective theory (EFT) paradigm, opacity of the IR region induced by higher dimensional operators censors the region of EFT breakdown. This confirms earlier expectations from the literature. Specializing to AdS5, we determine a universal contribution to opacity from gravity.

scholarly journals Classical gravitational self-energy from double copy

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Gabriel Luz Almeida ◽  
Stefano Foffa ◽  
Riccardo Sturani
Keyword(s):  
Gravitational Field ◽  
Binary System ◽  
The Self ◽  
Gravitational Coupling ◽  
Leading Order ◽  
Body System ◽  
Self Energy ◽  
Composite Systems ◽  
Body Dynamics ◽  
Double Copy

Abstract We apply the classical double copy to the calculation of self-energy of composite systems with multipolar coupling to gravitational field, obtaining next-to-leading order results in the gravitational coupling GN by generalizing color to kinematics replacement rules known in literature. When applied to the multipolar description of the two-body system, the self-energy diagrams studied in this work correspond to tail processes, whose physical interpretation is of radiation being emitted by the non-relativistic source, scattered by the curvature generated by the binary system and then re-absorbed by the same source. These processes contribute to the conservative two-body dynamics and the present work represents a decisive step towards the systematic use of double copy within the multipolar post-Minkowskian expansion.

scholarly journals The self-energy of a confined quark

1983 ◽  
Vol 131 (4-6) ◽  
pp. 445-449 ◽  
Author(s):  
S. Goldhaber ◽  
T.H. Hansson ◽  
R.L. Jaffe
Keyword(s):  
The Self ◽  
Self Energy

A NEW HAMILTONIAN OF INTERACTION FOR FERMIONS

2005 ◽  
Vol 19 (13n14) ◽  
pp. 669-681 ◽  
Author(s):  
ANDREI DOLOCAN ◽  
VOICU OCTAVIAN DOLOCAN ◽  
VOICU DOLOCAN
Keyword(s):  
Interaction Energy ◽  
The Self ◽  
Lagrangian Formalism ◽  
Expectation Values ◽  
Boson System ◽  
Self Energy ◽  
Fermion Gas

Using the Lagrangian formalism we attempt to introduce a new Hamiltonian for fermions. On this basis we have evaluated the expectation values for the interaction energy between fermions via bosons. The interaction energy between two fermions via phonons becomes attractive in a degenerate fermion-gas. The interaction energy between two fermions via photons appears to be attractive in certain conditions. The self-energy of the fermion + boson system, e.g. polaron and polariton, was evaluated.

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