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In this Brief Report, we present an algorithm for calculating the elastic Lattice Greens Function of a regular lattice, in which defects are created by removing lattice points. The method is computationally efficient, since the required…

Materials Science · Physics 2009-10-28 J. Schiøtz , A. E. Carlsson

Beyond the second-order Born approximation, we develop an improved master equation approach to quantum transport by virtue of a self-consistent Born approximation. The basic idea is replacing the free Green's function in the tunneling…

Mesoscale and Nanoscale Physics · Physics 2014-06-27 Jun Li , Jinshuang Jin , Xin-Qi Li , YiJing Yan

A new method for calculation of band structure has been proposed based on the Green's function theory and local sampling. Potential energy in the Hamiltonian of Schrodinger's equation is approximated with a series of sampled Dirac delta…

Mesoscale and Nanoscale Physics · Physics 2010-02-24 Milad Khoshnegar , Sina Khorasani , Amirhossein Hosseinnia

We modify the Green operator involved in Fourier-based computational schemes in elasticity, in 2D and 3D. The new operator is derived by expressing continuum mechanics in terms of centered differences on a rotated grid. Use of the modified…

Numerical Analysis · Mathematics 2015-02-20 François Willot

An efficient implementation of the nonequilibrium Green function (NEGF) method combined with the density functional theory (DFT) using localized pseudo-atomic orbitals (PAOs) is presented for electronic transport calculations of a system…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Taisuke Ozaki , Kengo Nishio , Hiori Kino

This paper presents a novel factorization-based, low-rank regularization method for solving multidimensional deconvolution problems in the frequency domain. In this approach, each frequency component of the unknown wavefield is represented…

Geophysics · Physics 2024-10-29 Fuqiang Chen , Matteo Ravasi , David Keyes

We present an efficient numerical approach for treating ballistic quantum transport across devices described by tight binding (TB) Hamiltonians designated to systems with localized potential defects. The method is based on the wave function…

Mesoscale and Nanoscale Physics · Physics 2016-09-08 K. Kolasiński , A. Mreńca-Kolasińska , B. Szafran

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 most popular method for computing the matrix logarithm is a combination of the inverse scaling and squaring method in conjunction with a Pad\'e approximation, sometimes accompanied by the Schur decomposition. The main computational…

Numerical Analysis · Mathematics 2024-01-19 Elias Jarlebring , Jorge Sastre , J. Javier Ibáñez González

We introduce a Green's function method for handling radiative effects on false vacuum decay. In addition to the usual thin-wall approximation, we achieve further simplification by treating the bubble wall in the planar limit. As an…

High Energy Physics - Theory · Physics 2015-06-03 Bjorn Garbrecht , Peter Millington

In this work we have presented a rather general and easy-to-apply method for discrete Hilbert space representation of quantum mechanical Green's operators. We have shown that if in some discrete Hilbert space basis representation the…

Quantum Physics · Physics 2016-09-08 Balázs Kónya

In this manuscript, we develop an efficient algorithm to evaluate the azimuthal Fourier components of the Green's function for the Helmholtz equation in cylindrical coordinates. A computationally efficient algorithm for this modal Green's…

Numerical Analysis · Mathematics 2022-10-05 James Garritano , Yuval Kluger , Vladimir Rokhlin , Kirill Serkh

We present a simple recipe to construct the Green's function associated with a Hamiltonian of the form H=H_0+V, where H_0 is a Hamiltonian for which the associated Green's function is known and V is a delta-function potential. We apply this…

Quantum Physics · Physics 2007-05-23 R. M. Cavalcanti

The term GreenAI refers to a novel approach to Deep Learning, that is more aware of the ecological impact and the computational efficiency of its methods. The promoters of GreenAI suggested the use of Floating Point Operations (FLOPs) as a…

Machine Learning · Computer Science 2025-11-06 Andrea Asperti , Davide Evangelista , Moreno Marzolla

We consider the factorization of a rectangular matrix $X $ into a positive linear combination of rank-one factors of the form $u v^\top$, where $u$ and $v$ belongs to certain sets $\mathcal{U}$ and $\mathcal{V}$, that may encode specific…

Machine Learning · Computer Science 2013-09-13 Francis Bach

This review is devoted to the different techniques that have been developed to compute the phase-coherent transport properties of quantum nanoelectronic systems connected to electrodes. Beside a review of the different algorithms proposed…

Quantum transport of strongly correlated fermions is of central interest in condensed matter physics. Here, we present first-principle nonequilibrium Green functions results using $T$-matrix selfenergies for finite Hubbard clusters of…

Quantum Gases · Physics 2016-01-15 N. Schlünzen , S. Hermanns , M. Bonitz , C. Verdozzi

We explicitly calculate the Green functions describing quantum changes of topology in Friedman-Lemaitre-Robertson-Walker Universes whose spacelike sections are compact but endowed with distinct topologies. The calculations are performed…

General Relativity and Quantum Cosmology · Physics 2010-02-03 Jerome Martin , Nelson Pinto-Neto , Ivano Damiao Soares

The magnon Hedin's equations are derived via the Schwinger functional derivative technique, and the resulting self-consistent Green's function method is used to calculate ground state spin patterns and magnetic structure factors for…

Strongly Correlated Electrons · Physics 2022-11-30 Zhen Zhao , Claudio Verdozzi , Ferdi Aryasetiawan

The Non-equilibrium Green's function (NEGF) formalism is a particularly powerful method to simulate the quantum transport properties of nanoscale devices such as transistors, photo-diodes, or memory cells, in the ballistic limit of…

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