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Photon Green function (GF) is the vital and most decisive factor in the field of quantum light-matter interaction. It is divergent with two equal space arguments in arbitrary-shaped lossy structure and should be regularized. We introduce a…

We present a further development of methods for analytical calculations of Green's functions of lattice fermions based on recurrence relations. Applying it to tight-binding systems and topological superconductors in different dimensions we…

Mesoscale and Nanoscale Physics · Physics 2017-10-11 A. Komnik , S. Heinze

This paper develops a finite-difference analogue of the boundary integral/element method for the numerical solution of two-dimensional exterior scattering from scatterers of arbitrary shapes. The discrete fundamental solution, known as the…

Numerical Analysis · Mathematics 2025-11-19 Siyuan Wang , Qing Xia

Lattice Green's Functions (LGFs) are fundamental solutions to discretized linear operators, and as such they are a useful tool for solving discretized elliptic PDEs on domains that are unbounded in one or more directions. The majority of…

Numerical Analysis · Mathematics 2025-04-01 James Gabbard , Wim M. van Rees

We propose a mesh refinement technique for solving elliptic difference equations on unbounded domains based on the fast lattice Green's function (FLGF) method. The FLGF method exploits the regularity of the Cartesian mesh and uses the fast…

Computational Physics · Physics 2020-02-19 Benedikt Dorschner , Ke Yu , Gianmarco Mengaldo , Tim Colonius

In the graph-based semi-supervised learning, the Green-function method is a classical method that works by computing the Green's function in the graph space. However, when applied to large graphs, especially those sparse ones, this method…

Machine Learning · Computer Science 2024-11-05 Feiping Nie , Yitao Song , Wei Chang , Rong Wang , Xuelong Li

Let $\Gamma$ be geometric tree graph with $m$ edges and consider the second order Sturm-Liouville operator $\L[u]=(-pu')'+qu$ acting on functions that are continuous on all of $\Gamma$, and twice continuously differentiable in the interior…

Classical Analysis and ODEs · Mathematics 2011-08-03 Jorge M Ramirez

One of the most common methods to train machine learning algorithms today is the stochastic gradient descent (SGD). In a distributed setting, SGD-based algorithms have been shown to converge theoretically under specific circumstances. A…

Machine Learning · Computer Science 2025-08-22 Soumya Sarkar , Shweta Jain

This paper presents a windowed Green function (WGF) method for the numerical solution of problems of elastic scattering by "locally-rough surfaces" (i.e., local perturbations of a half space), under either Dirichlet or Neumann boundary…

Computational Physics · Physics 2021-02-03 Oscar P. Bruno , Tao Yin

In this work we present a three step procedure for generating a closed form expression of the Green's function on both closed and open finite quantum graphs with general self-adjoint matching conditions. We first generalize and simplify the…

Quantum Physics · Physics 2023-09-21 Tristan Lawrie , Sven Gnutzmann , Gregor Tanner

We study distributed optimization algorithms for minimizing the average of \emph{heterogeneous} functions distributed across several machines with a focus on communication efficiency. In such settings, naively using the classical stochastic…

Machine Learning · Computer Science 2020-11-18 Ilqar Ramazanli , Han Nguyen , Hai Pham , Sashank J. Reddi , Barnabas Poczos

Following a proposal by Aronov and Ioselevich, we express the Green functions (GF) of a noninteracting disordered Fermi system as a functional integral on a real time/frequency lattice. The normalizing denominator of this functional…

Condensed Matter · Physics 2007-05-23 W. Weller , F. Stefani , M. Souleiman

Many force-gradient explicit symplectic integration algorithms have been designed for the Hamiltonian $H=T (\mathbf{p})+V(\mathbf{q})$ with kinetic energy $T(\mathbf{p})=\mathbf{p}^2/2$ in the existing references. When the force-gradient…

Numerical Analysis · Mathematics 2021-11-10 Lina Zhang , Xin Wu , Enwei Liang

A method to calculate exact Green's functions on lattices in various dimensions is presented. Expressions in terms of generalized hypergeometric functions in one or more variables are obtained for various examples by relating the resolvent…

Mathematical Physics · Physics 2014-09-30 Koushik Ray

The single-particle Green's function of an interacting Fermi system with dominant forward scattering is calculated by decoupling the interaction by means of a Hubbard-Stratonowich transformation involving a bosonic auxiliary field…

Condensed Matter · Physics 2007-05-23 Peter Kopietz

This paper introduces a fast algorithm, applicable throughout the electromagnetic spectrum, for the numerical solution of problems of scattering by periodic surfaces in two-dimensional space. The proposed algorithm remains highly accurate…

Computational Physics · Physics 2018-05-25 Oscar Bruno , Martín Maas

The Gaussian homotopy (GH) method is a popular approach to finding better stationary points for non-convex optimization problems by gradually reducing a parameter value $t$, which changes the problem to be solved from an almost convex one…

Optimization and Control · Mathematics 2022-11-17 Hidenori Iwakiri , Yuhang Wang , Shinji Ito , Akiko Takeda

We introduce a performance-optimized method to simulate localization problems on bipartite tight-binding lattices. It combines an exact renormalization group step to reduce the sparseness of the original problem with the recursive Green's…

Disordered Systems and Neural Networks · Physics 2021-06-08 Martin Puschmann , Thomas Vojta

Following early work on Hessian-free methods for deep learning, we study a stochastic generalized Gauss-Newton method (SGN) for training DNNs. SGN is a second-order optimization method, with efficient iterations, that we demonstrate to…

Machine Learning · Computer Science 2020-06-11 Matilde Gargiani , Andrea Zanelli , Moritz Diehl , Frank Hutter

Variational inference has experienced a recent surge in popularity owing to stochastic approaches, which have yielded practical tools for a wide range of model classes. A key benefit is that stochastic variational inference obviates the…

Computer Vision and Pattern Recognition · Computer Science 2018-03-29 Tobias Plötz , Anne S. Wannenwetsch , Stefan Roth