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We present a method for approximating the many-body density of states of a system of quantum identical particles, with a reduction of the computational cost by a combinatorial factor compared to the full calculation. This is carried out by…

Quantum Physics · Physics 2026-05-05 Hovan Lee , Rémi Lefèvre , Grégoire Ithier

In this article we study the effects of higher body excitations in the relativistic CC calculations for atoms and ions with one valence electron using Fock-space CCSD, CCSD(T) and its unitary variants. The present study demonstrates that…

Atomic Physics · Physics 2009-11-13 Chiranjib Sur , Rajat K Chaudhuri

Calculations of observables in Quantum Chromodynamics are typically performed using a method that combines numerical integrations over the momenta of final state particles with analytical integrations over the momenta of virtual particles.…

High Energy Physics - Phenomenology · Physics 2009-10-31 Davison E. Soper

The introduction of gases like nitrogen or neon for cooling the edge region of magnetically confined fusion plasmas has triggered a renewed interest in state selective cross sections necessary for plasma diagnostics by means of charge…

Modern particle physics is increasingly becoming a precision science that relies on advanced theoretical predictions for the analysis and interpretation of experimental results. The planned physics program at the LHC and future colliders…

High Energy Physics - Phenomenology · Physics 2023-01-04 Ievgen Dubovyk , Ayres Freitas , Janusz Gluza , Krzysztof Grzanka , Martijn Hidding , Johann Usovitsch

We generalize a recently developed method for accelerated Monte Carlo calculation of path integrals to the physically relevant case of generic many-body systems. This is done by developing an analytic procedure for constructing a hierarchy…

Statistical Mechanics · Physics 2011-08-08 Aleksandar Bogojevic , Ivana Vidanovic , Antun Balaz , Aleksandar Belic

The process of fusion of complex nuclei is of significant interest as an example of the collective nuclear motion of large amplitude as well as a route for synthesis of new superheavy chemical elements. This process is accompanied by the…

Nuclear Theory · Physics 2023-05-23 I. I. Gontchar , M. V. Chushnyakova

Despite rapid progress in the development of quantum algorithms in quantum computing as well as numerical simulation methods in classical computing for atomic and molecular applications, no systematic and comprehensive electronic structure…

A second-order many-body perturbation correction to the relativistic Dirac-Hartree-Fock energy is evaluated stochastically by integrating 13-dimensional products of four-component spinors and Coulomb potentials. The integration in the real…

Quantum Physics · Physics 2022-06-16 J. César Cruz , Jorge Garza , Takeshi Yanai , So Hirata

In this article, we present an interpolative separable density fitting (ISDF) based algorithm to calculate exact exchange in periodic mean field calculations. In the past, decomposing the two-electron integrals into tensor hypercontraction…

Chemical Physics · Physics 2024-04-16 Kori E. Smyser , Alec White , Sandeep Sharma

Being exact at both short- and long-time limits, the Gaussian approximation is widely used to calculate neutron incoherent inelastic scattering functions in liquids. However, to overcome a few numerical difficulties, extra physical…

Computational Physics · Physics 2022-07-27 Rong Du , Xiao-Xiao Cai

In order to interpret and predict the behavior and properties of fusion plasma, accurate cross sections for electronic processes in collisions between plasma impurities and atomic hydrogen are required. In this work, we investigate the…

Atomic Physics · Physics 2024-12-30 C. C. Jia , Y. Y. Qi , J. J. Niu , Y. Wu J. G. Wang , A. Dubois , N. Sisourat , J. W. Gao

The double-differential cross sections (DDCS) for $n + ^{19}$F reaction is of critical importance for elucidating the mechanisms of nuclear reaction processes, advancing applications in nuclear engineering and technology, and supporting…

Nuclear Theory · Physics 2025-09-22 Hanmei Cao , Fanglei Zou , Xiaojun Sun , Jingshang Zhang

This paper introduces a new fast algorithm for the 8-point discrete cosine transform (DCT) based on the summation-by-parts formula. The proposed method converts the DCT matrix into an alternative transformation matrix that can be decomposed…

Data Structures and Algorithms · Computer Science 2018-03-30 D. F. G. Coelho , R. J. Cintra , V. S. Dimitrov

This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I: One outgoing channel of interest from cold collisions is the production of ion pairs. We…

Optics · Physics 2013-10-21 Lisa Madeleine Ugray

The Displacement per Atom (DPA) rate is conventionally computed with DPA cross sections in reactor applications. The method of direct calculation with energy-angular distributions given in the Center of Mass (CM) frame is proposed and…

Instrumentation and Detectors · Physics 2019-07-30 Shengli Chen , David Bernard , Pierre Tamagno , Jean Tommasi , Stephane Bourganel , Gilles Noguere , Cyrille De Saint Jean

We propose a novel method, called the dimension-changing transformation (DCT), to compute one-loop Feynman integrals and recently introduced fixed-branch integrals to arbitrary orders in $\epsilon$. The DCT relates one-loop Feynman…

High Energy Physics - Phenomenology · Physics 2024-12-31 Rui-Jun Huang , Dong-Shan Jian , Yan-Qing Ma , Dao-Ming Mu , Wen-Hao Wu

Fully differential cross sections are calculated for the ionization of H$_2$ by fast charged projectiles using a semiclassical model developed previously for the ionization of atoms. The method is tested in case of 4 keV electron and 6 MeV…

Atomic Physics · Physics 2009-12-07 F. Jarai-Szabo , K. Nagy-Pora , L Nagy

The $4f-5d$ transition rates for rare-earth ions in crystals can be calculated with an effective transition operator acting between model $4f^N$ and $4f^{N-1}5d$ states calculated with effective Hamiltonian, such as semi-empirical crystal…

Materials Science · Physics 2007-05-23 Chang-Kui Duan , Michael F. Reid

Treatment with high energy ionizing radiation is one of the main methods in modern cancer therapy that is in clinical use. During the last decades, two main approaches to dose calculation were used, Monte Carlo simulations and…

Medical Physics · Physics 2015-05-14 Roland Duclous , Bruno Dubroca , Martin Frank