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Complex valued systems with an indefinite matrix term arise in important applications such as for certain time-harmonic partial differential equations such as the Maxwell's equation and for the Helmholtz equation. Complex systems with…

Numerical Analysis · Mathematics 2021-10-04 Owe Axelsson , Maeddeh Pourbagher , Davod Khojasteh Salkuyeh

Shell-model calculations play a key role in elucidating various properties of nuclei. In general, those studies require a huge number of calculations to be repeated for parameter calibration and quantifying uncertainties. To reduce the…

Nuclear Theory · Physics 2022-06-01 Sota Yoshida , Noritaka Shimizu

Transformation matrices between different coupling schemes are required, if a reliable classification of the level structure is to be obtained for open-shell atoms and ions. While, for instance, relativistic computations are traditionally…

Atomic Physics · Physics 2009-11-10 G. Gaigalas , S. Fritzsche

We introduce a semistochastic implementation of the power method to compute, for very large matrices, the dominant eigenvalue and expectation values involving the corresponding eigenvector. The method is semistochastic in that the matrix…

Strongly Correlated Electrons · Physics 2013-10-24 F. R. Petruzielo , A. A. Holmes , Hitesh J. Changlani , M. P. Nightingale , C. J. Umrigar

This paper proposes several explicit and implicit multistep frequency response optimized integrators considering first or second order derivative. A prediction-based method aiming at accelerating a novel power system transient simulation…

Systems and Control · Electrical Eng. & Systems 2021-02-16 Sheng Lei , Alexander Flueck

Construction and diagonalization of the Hamiltonian matrix is the rate-limiting step in most low-energy electron -- molecule collision calculations. Tennyson (J Phys B, 29 (1996) 1817) implemented a novel algorithm for Hamiltonian…

Computational Physics · Physics 2017-09-12 Ahmed F. Al-Refaie , Jonathan Tennyson

Large-scale earthquake sequence simulations using the boundary element method (BEM) incur extreme computational costs through multiplying a dense matrix with a slip rate vector. Hierarchical matrices (H-matrices) have often been used to…

Computational Physics · Physics 2022-10-26 So Ozawa , Akihiro Ida , Tetsuya Hoshino , Ryosuke Ando

Obtaining a rigorous and reliable method for linking computer simulations of polymer blends and composites at different length scales of interest is a highly desirable goal in soft matter physics. In this paper a multiscale modeling…

Soft Condensed Matter · Physics 2015-05-19 J. McCarty , M. G. Guenza

In recent years, interface quasi-Newton methods have gained growing attention in the fluid-structure interaction community by significantly improving partitioned solution schemes: They not only help to control the inherent added-mass…

Computational Engineering, Finance, and Science · Computer Science 2020-01-23 Thomas Spenke , Norbert Hosters , Marek Behr

Quantum Monte Carlo (QMC) methods are often used to calculate properties of many body quantum systems. The main cost of many QMC methods, for example the variational Monte Carlo (VMC) method, is in constructing a sequence of Slater matrices…

Strongly Correlated Electrons · Physics 2011-05-10 Kapil Ahuja , Bryan K. Clark , Eric de Sturler , David M. Ceperley , Jeongnim Kim

We present a multiscale integrator for Hamiltonian systems with slowly varying quadratic stiff potentials that uses coarse timesteps (analogous to what the impulse method uses for constant quadratic stiff potentials). This method is based…

Numerical Analysis · Mathematics 2011-04-14 Molei Tao , Houman Owhadi , Jerrold E. Marsden

For the first time, the calculation of the nuclear matrix element of the double-$\beta$ decay of $^{100}$Mo, with and without the emission of two neutrinos, is performed in the framework of the nuclear shell model. This task is accomplished…

Nuclear Theory · Physics 2022-03-23 L. Coraggio , N. Itaco , G. De Gregorio , A. Gargano , R. Mancino , F. Nowacki

By combining Hartree-Fock with a neural-network-supported quantum-cluster solver proposed recently in the context of solid-state lattice models, we formulate a scheme for selective neural-network configuration interaction (NNCI)…

Using the quark-meson coupling model, we calculate the form factors at sigma- and omega-nucleon strong-interaction vertices in nuclear matter. The Peierls-Yoccoz projection technique is used to take account of center of mass and recoil…

Nuclear Theory · Physics 2007-05-23 K. Saito , K. Tsushima

The computational cost of ab initio nuclear structure calculations is rendered particularly acute by the presence of (at least) three-nucleon interactions. This feature becomes especially critical now that many-body methods aim at extending…

We summarize our recent efforts to develop the Density Matrix Renormalization Group (DMRG) method into a practical truncation strategy for large-scale nuclear shell model calculations. Following an overview of the essential features of the…

Nuclear Theory · Physics 2009-04-16 S. Pittel , B. Thakur

Benchmark comparisons between many-body methods are performed to assess the ingredients necessary for an accurate calculation of neutrinoless double beta decay matrix elements. Shell model and variational Monte Carlo (VMC) calculations are…

Nuclear Theory · Physics 2019-10-15 X. B. Wang , A. C. Hayes , J. Carlson , G. X. Dong , E. Mereghetti , S. Pastore , R. B. Wiringa

The efficient computation of Jacobians represents a fundamental challenge in computational science and engineering. Large-scale modular numerical simulation programs can be regarded as sequences of evaluations of in our case differentiable…

Numerical Analysis · Mathematics 2020-10-13 Uwe Naumann

The matrix element method utilizes ab initio calculations of probability densities as powerful discriminants for processes of interest in experimental particle physics. The method has already been used successfully at previous and current…

Computational Physics · Physics 2015-05-20 Doug Schouten , Adam DeAbreu , Bernd Stelzer

The dynamical symmetries of the Fermion Dynamical Symmetry Model are used as a principle of truncation for the spherical shell model. Utilizing the usual principle of energy-dictated truncation to select a valence space, and…

Nuclear Theory · Physics 2009-10-28 M. W. Guidry , D. H. Feng , X. W. Pan , C. -L. Wu