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Accurate determination of opacity is critical for understanding radiation transport in both astrophysical and laboratory plasmas. We employ atomic data from R-Matrix calculations to investigate radiative properties in high-energy-density…

High Energy Astrophysical Phenomena · Physics 2025-10-24 Anil K. Pradhan , Sultana N. Nahar

We introduce 1-RDMFT in the canonical ensemble and then proceed to approximate the interacting ensemble by a non-interacting ensemble that maximizes the entropy, independently of temperature. Bosonic and Fermionic Sinkhorn algorithms are…

Chemical Physics · Physics 2022-05-31 Derk P. Kooi

Selective configuration interaction methods approximate correlated molecular ground- and excited states by considering only the most relevant Slater determinants in the expansion. While a recently proposed neural-network-assisted approach…

We present a detailed model of the discrete X-ray spectroscopic features expected from steady-state, low-density photoionized plasmas. We apply the Flexible Atomic Code (FAC) to calculate all of the necessary atomic data for the full range…

Astrophysics · Physics 2007-05-23 A. Kinkhabwala , E. Behar , M. Sako , M. F. Gu , S. M. Kahn , F. B. S. Paerels

In this article we describe the design, construction and implementation of our ion-atom hybrid system incorporating a high resolution time of flight mass spectrometer (TOFMS). Potassium atoms ($^{39}$K) in a Magneto Optical Trap (MOT) and…

Asymptotics-based configuration-interaction (CI) methods [G. Friesecke and B. D. Goddard, Multiscale Model. Simul. 7, 1876 (2009)] are a class of CI methods for atoms which reproduce, at fixed finite subspace dimension, the exact…

Quantum Physics · Physics 2012-04-06 Christian Mendl , Gero Friesecke

We describe how a new framework for coupling a full-PIC algorithm with a reduced PIC algorithm has been implemented into the code OSIRIS. We show that OSIRIS with this new hybrid-PIC algorithm can efficiently and accurately model high…

Plasma Physics · Physics 2012-05-15 F. Fiuza , M. Marti , R. A. Fonseca , L. O. Silva , J. Tonge , J. May , W. B. Mori

We present the concept, derivation, and implementation of dynamical configuration interaction, a quantum embedding theory that combines Green's function methodology with the many-body wave function. In a strongly-correlated active space, we…

Chemical Physics · Physics 2019-04-03 Marc Dvorak , Patrick Rinke

The trapping lasers of a magneto-optical trap (MOT) are used to bring Rb atoms into well defined oriented states. Coupled to recoil-ion momentum spectroscopy (RIMS), this yields a unique MOTRIMS setup which is able to probe scattering…

Atomic Physics · Physics 2013-09-30 A. Leredde , X. Fléchard , A. Cassimi , D. Hennecart , B. Pons

We have performed systematic large-scale all-electron correlated calculations on boron clusters B$_{n}$(n=2--5), to study their linear optical absorption spectra. Several possible isomers of each cluster were considered, and their…

Atomic and Molecular Clusters · Physics 2012-08-27 Ravindra Shinde , Alok Shukla

The one-dimensional configuration coordinate model (1D-CCM) is widely used for the analysis of photoluminescence in molecules and doped solids, and relies on a linear combination of the equilibrium nuclear configurations of ground and…

Materials Science · Physics 2019-10-23 Yongchao Jia , Samuel Poncé , Anna Miglio , Masayoshi Mikami , Xavier Gonze

Many applications are in need of accurate photoionization cross-sections, especially in the case of complex atoms. Configuration-interaction relativistic many-body perturbation theory (CI-RMBPT) that has been successful in predicting atomic…

Atomic Physics · Physics 2014-10-09 I. M. Savukov , D. V. Filin

It is demonstrated that the reaction path for a polyatomic molecule (applied to the HCO molecule) is easily calculated via ab-initio configuration interaction (CI) total energies. This Hamiltonian not only reproduces the CI calculations…

Chemical Physics · Physics 2007-05-23 N. C. Bacalis , A. Metropoulos , D. A. Papaconstantopoulos

We show that the recent experimental realization of spin-orbit coupling in ultracold atomic gases can be used to study different types of spin spiral order and resulting multiferroic effects. Spin-orbit coupling in optical lattices can give…

Quantum Gases · Physics 2015-06-01 Ming Gong , Yinyin Qian , Mi Yan , V. W. Scarola , Chuanwei Zhang

We present our implementation autoCAS for fully automated multi-configurational calculations, which we also make available free of charge on our webpages. The graphical user interface of autoCAS connects a general electronic structure…

Chemical Physics · Physics 2019-12-03 Christopher J. Stein , Markus Reiher

We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in…

Chemical Physics · Physics 2022-10-19 Stefanos Carlström , Michael Spanner , Serguei Patchkovskii

We theoretically investigate photoresponses of a correlated electron system upon stimuli of a pulsed laser light. Real-time dynamics of an interacting spinless fermion model on a one-dimensional chain, as a model of charge order (CO), are…

Strongly Correlated Electrons · Physics 2019-01-14 Hitoshi Seo , Yasuhiro Tanaka , Sumio Ishihara

The hierarchical equations of motion (HEOM) approach is an accurate method to simulate open system quantum dynamics, which allows for systematic convergence to numerically exact results. To represent the effects of the bath, the reservoir…

Strongly Correlated Electrons · Physics 2023-05-31 Xiaohan Dan , Meng Xu , J. T. Stockburger , J. Ankerhold , Qiang Shi

The present study presents a comprehensive theoretical investigation of atom and asymmetric top molecule inelastic scattering based on the R-matrix formalism. The proposed methodology establishes a rigorous framework for treating inelastic…

An active space variational calculation of the 2-electron reduced density matrix (2-RDM) is derived and implemented where the active orbitals are correlated within the pair approximation. The pair approximation considers only doubly…

Chemical Physics · Physics 2020-10-13 Kade Head-Marsden , David A. Mazziotti