Liouvillian propagator technique for perturbed wave functions, level shifts and broadenings of composite particles in a many-body medium

1981 ◽  
pp. 355-363
Author(s):  
M. D. Girardeau
Keyword(s):  
Wave Functions ◽  
Composite Particles ◽  
Many Body ◽  
Level Shifts

scholarly journals Many-body localization transition in Rokhsar-Kivelson-type wave functions

2015 ◽  
Vol 92 (21) ◽  
Author(s):  
Xiao Chen ◽  
Xiongjie Yu ◽  
Gil Young Cho ◽  
Bryan K. Clark ◽  
Eduardo Fradkin
Keyword(s):  
Wave Functions ◽  
Many Body ◽  
Localization Transition ◽  
Type Wave

scholarly journals Hermitizing the HAL QCD potential in the derivative expansion

2020 ◽  
Vol 2020 (2) ◽  
Author(s):  
Sinya Aoki ◽  
Takumi Iritani ◽  
Koichi Yazaki
Keyword(s):  
Phase Shift ◽  
Wave Functions ◽  
Leading Order ◽  
Many Body ◽  
Derivative Expansion ◽  
Local Part ◽  
Scattering Phase ◽  
Many Body Systems ◽  
Local Term ◽  
Better Than

Abstract A formalism is given to hermitize the HAL QCD potential, which needs to be non-Hermitian except for the leading-order (LO) local term in the derivative expansion as the Nambu– Bethe– Salpeter (NBS) wave functions for different energies are not orthogonal to each other. It is shown that the non-Hermitian potential can be hermitized order by order to all orders in the derivative expansion. In particular, the next-to-leading order (NLO) potential can be exactly hermitized without approximation. The formalism is then applied to a simple case of $\Xi \Xi (^{1}S_{0}) $ scattering, for which the HAL QCD calculation is available to the NLO. The NLO term gives relatively small corrections to the scattering phase shift and the LO analysis seems justified in this case. We also observe that the local part of the hermitized NLO potential works better than that of the non-Hermitian NLO potential. The Hermitian version of the HAL QCD potential is desirable for comparing it with phenomenological interactions and also for using it as a two-body interaction in many-body systems.

Number operators for composite particles in nonrelativistic many‐body theory

1980 ◽  
Vol 21 (8) ◽  
pp. 2164-2169 ◽  
Author(s):  
Wesley E. Brittin ◽  
Arthur Y. Sakakura
Keyword(s):  
Composite Particles ◽  
Many Body ◽  
Many Body Theory ◽  
Body Theory

scholarly journals Electronic structure and core electron fingerprints of caesium-based multi-alkali antimonides for ultra-bright electron sources

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Caterina Cocchi ◽  
Sonal Mistry ◽  
Martin Schmeißer ◽  
Raymond Amador ◽  
Julius Kühn ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Cost Effective ◽  
Binding Energies ◽  
Many Body ◽  
Core Electron ◽  
Operational Conditions ◽  
Electron Sources ◽  
Level Shifts ◽  
Many Body Perturbation Theory

AbstractThe development of novel photocathode materials for ultra-bright electron sources demands efficient and cost-effective strategies that provide insight and understanding of the intrinsic material properties given the constraints of growth and operational conditions. To address this question, we propose a viable way to establish correlations between calculated and measured data on core electronic states of Cs-K-Sb materials. To do so, we combine first-principles calculations based on all-electron density-functional theory on the three alkali antimonides Cs3Sb, Cs2KSb, and CsK2Sb with x-ray photoemission spectroscopy (XPS) on Cs-K-Sb photocathode samples. Within the GW approximation of many-body perturbation theory, we obtain quantitative predictions of the band gaps of these materials, which range from 0.57 eV in Cs2KSb to 1.62 eV in CsK2Sb and manifest direct or indirect character depending on the relative potassium content. Our theoretical electronic-structure analysis also reveals that the core states of these systems have binding energies that depend only on the atomic species and their crystallographic sites, with largest shifts of the order of 2 eV and 0.5 eV associated to K 2p and Sb 3d states, respectively. This information can be correlated to the maxima in the XPS survey spectra, where such peaks are clearly visible. In this way, core-level shifts can be used as fingerprints to identify specific compositions of Cs-K-Sb materials and their relation with the measured values of quantum efficiency. Our results represent the first step towards establishing a robust connection between the experimental preparation and characterization of photocathodes, the ab initio prediction of their electronic structure, and the modeling of emission and beam formation processes.

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