The rational function approximation provides a natural and interpretable representation of response functions such as the many-body spectral functions. We apply the vector fitting (VFIT) algorithm to fit a variety of spectral functions calculated from the Holstein model of electron-phonon interactions. We show that the resulting rational functions are highly efficient in their fitting of sharp features in the spectral functions, and could provide a means to infer physically relevant information from a spectral data set. The position of the peaks in the approximated spectral function are determined by the location of poles in the complex plane. In addition, we developed a variant of VFIT that incorporates regularization to improve the quality of fits. With this procedure, we demonstrate it is possible to achieve accurate spectral function fits that vary smoothly as a function of physical conditions.
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http://dx.doi.org/10.1103/PhysRevE.109.015302 | DOI Listing |
Phys Rev Lett
December 2024
Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Division, Upton, New York 11973, USA.
We present a protocol for detecting multipartite entanglement in itinerant many-body electronic systems using single-particle Green's functions. To achieve this, we first establish a connection between the quantum Fisher information and single-particle Green's functions by constructing a set of witness operators built out of single electron creation and destruction operators in a doubled system. This set of witness operators is indexed by a momentum k.
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Graduate School of Science and Technology, Shizuoka University, Shizuoka, Japan.
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January 2025
Department of Psychology, University of Texas at Dallas, Richardson, Texas, USA.
Aggression is commonly associated with increased experiences of peer rejection and maladaptive social information processing biases throughout development. Little is known about the neural correlates of peer rejection that might underlie social information processing biases, and whether these neural correlates are common or different across early- and mid-adolescents on a continuum of aggression. Using the Cyberball task, we examined mediofrontal theta (4-7 Hz) event-related EEG spectral power during conditions of explicit and ambiguous social exclusion in 117 participants (57 early adolescents, ages 10-12 years, and 60 mid-adolescents, ages 14-16 years).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
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Jilin University, State Key Laboratory of Supramolecular Structure and Materials, 2699 Qianjin Street, 130012, Changchun, CHINA.
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View Article and Find Full Text PDFJ Org Chem
January 2025
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Thiophene and pyrrole units are extensively utilized in light-responsive materials and have significantly advanced the field of organic photovoltaics (OPV). This progress has inspired our exploration of photosensitizers (PS) for photodynamic therapy (PDT). Currently, traditional PS face limitations in clinical application, including a restricted variety and narrow applicability.
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