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An important problem in many-body physics is to reconstruct the spectral density from the imaginary-time domain Green's function. Typically, the imaginary-time Green's function is generated by Monte Carlo methods. As the one-point fermionic…

Strongly Correlated Electrons · Physics 2026-02-24 Fakher Assaad , Johanna Erdmenger , Anika Götz , René Meyer , Martin Rackl , Yanick Thurn

Non equilibrium Green's function methods are regularly used to calculate current and charge densities in nanoscale (both molecular and semiconductor) conductors under bias. This method is mainly used for ballistic conduction but may be…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 M. Paulsson

The Kernel Polynomial Method (KPM) is one of the fast diagonalization methods used for simulations of quantum systems in research fields of condensed matter physics and chemistry. The algorithm has a difficulty to be parallelized on a…

Computational Physics · Physics 2011-05-30 Shixun Zhang , Shinichi Yamagiwa , Masahiko Okumura , Seiji Yunoki

Bulk modes (BM) are basis solutions to the Schr\"{o}dinger equation and they are useful in a number of physical problems. In the present work, we establish a complete set of BMs for graphene ribbons at arbitrary energy. We derive analytical…

Mesoscale and Nanoscale Physics · Physics 2014-12-10 Hai-Yao Deng , Katsunori Wakabayashi

We present a general representation for solving problems in many-body perturbation theory. By projecting the single-particle Green's function to an auxiliary space we show how one can convert an arbitrary Feynman graph to a universal kernel…

Strongly Correlated Electrons · Physics 2025-11-05 Daria Gazizova , Rayan Farid , B. D. E. McNiven , I. Assi , Ethan G. Armstrong , J. P. F. LeBlanc

Learning the Green's function using deep learning models enables to solve different classes of partial differential equations. A practical limitation of using deep learning for the Green's function is the repeated computationally expensive…

Machine Learning · Computer Science 2023-08-02 Kishan Wimalawarne , Taiji Suzuki , Sophie Langer

We apply the method of two-point quasiclassical Green's function to geometries where the trajectories include interfering paths and loops. For a system of two superconducting layers separated by partially transparent interface, corrections…

Superconductivity · Physics 2009-11-07 M. Ozana , A. Shelankov

We propose a fast and versatile algorithm to calculate local and transport properties such as conductance, shot noise, local density of state or local currents in mesoscopic quantum systems. Within the non equilibrium Green function…

Mesoscale and Nanoscale Physics · Physics 2008-03-18 Kyryl Kazymyrenko , Xavier Waintal

Approximation of non-linear kernels using random feature maps has become a powerful technique for scaling kernel methods to large datasets. We propose $\textit{Tensor Sketch}$, an efficient random feature map for approximating polynomial…

Data Structures and Algorithms · Computer Science 2025-05-20 Ninh Pham , Rasmus Pagh

We present the multi-channel Dyson equation that combines two or more many-body Green's functions to describe the electronic structure of materials. In this work we use it to model photoemission spectra by coupling the one-body Green's…

Strongly Correlated Electrons · Physics 2023-10-03 Gabriele Riva , Pina Romaniello , J. Arjan Berger

Equilibrium measures are special invariant measures of chaotic dynamical systems and iterated function systems, commonly studied as salient examples of fractal measures. While useful analytic expressions are rare, computational exploration…

Dynamical Systems · Mathematics 2023-12-19 Caroline L. Wormell

We connect shift-invariant characteristic kernels to infinitely divisible distributions on $\mathbb{R}^{d}$. Characteristic kernels play an important role in machine learning applications with their kernel means to distinguish any two…

Machine Learning · Statistics 2016-10-26 Yu Nishiyama , Kenji Fukumizu

Peridynamics is a nonlocal generalization of continuum mechanics theory which adresses discontinuous problems without using partial derivatives and replacing its by an integral operator. As a consequence, it finds applications in the…

Numerical Analysis · Mathematics 2022-09-07 Luciano Lopez , Sabrina Francesca Pellegrino

In this work, we propose an efficient computational scheme for first-principle quantum transport simulations to evaluate the open-boundary conditions. Its partitioning differentiates from conventional methods in that the contact self-energy…

Materials Science · Physics 2021-01-01 Guido Gandus , Youseung Lee , Daniele Passerone , Mathieu Luisier

This paper presents for the first time a robust exact line-search method based on a full pseudospectral (PS) numerical scheme employing orthogonal polynomials. The proposed method takes on an adaptive search procedure and combines the…

Optimization and Control · Mathematics 2023-03-06 Kareem T. Elgindy

This paper proposes a novel kernel approach to linear dimension reduction for supervised learning. The purpose of the dimension reduction is to find directions in the input space to explain the output as effectively as possible. The…

Machine Learning · Statistics 2011-09-05 Kenji Fukumizu , Chenlei Leng

Kernel methods provide an elegant and principled approach to nonparametric learning, but so far could hardly be used in large scale problems, since na\"ive implementations scale poorly with data size. Recent advances have shown the benefits…

Machine Learning · Computer Science 2020-11-30 Giacomo Meanti , Luigi Carratino , Lorenzo Rosasco , Alessandro Rudi

} The main goal of this note is to provide new, mostly multidimensional densities, compactly supported and list many of its properties that enable effective calculations. The idea of obtaining such densities is firstly to build some…

Classical Analysis and ODEs · Mathematics 2018-08-08 Paweł J. Szabłowski

The multivariate integer Chebyshev problem is to find polynomials with integer coefficients that minimize the supremum norm over a compact set in $\C^d.$ We study this problem on general sets, but devote special attention to product sets…

Number Theory · Mathematics 2013-07-23 P. B. Borwein , I. E. Pritsker

The many-body Green's function provides access to electronic properties beyond density functional theory level in ab inito calculations. In this manuscript, we propose a deep learning framework for predicting the finite-temperature Green's…

Chemical Physics · Physics 2024-02-20 Xinyang Dong , Emanuel Gull , Lei Wang