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Based on self-consistent field (SCF) atomic mean-field (amf) quantities, we present two simple, yet computationally efficient and numerically accurate matrix-algebraic approaches to correct both scalar-relativistic \textit{and} spin-orbit…

Chemical Physics · Physics 2023-02-03 Stefan Knecht , Michal Repisky , Hans Jørgen Aagaard Jensen , Trond Saue

The formyl cation (HCO+) is one of the most abundant ions in molecular clouds and plays a major role in the interstellar chemistry. For this reason, accurate collisional rate coefficients for the rotational excitation of HCO+ and its…

Astrophysics of Galaxies · Physics 2022-08-31 Francesca Tonolo , François Lique , Mattia Melosso , Cristina Puzzarini , Luca Bizzocchi

We present an efficient implementation of a one-step relativistic second-order multireference perturbation theory based on the multireference driven similarity renormalization group (MR-DSRG) using the exact two-component (X2C) Hamiltonian,…

Chemical Physics · Physics 2026-05-13 Zijun Zhao , Francesco A. Evangelista

We have developed a new Hartree-Fock-Bogoliubov (HFB) code which has been specifically designed to study ground state properties of nuclei near the neutron and proton drip lines. The unique feature of our code is that it takes into account…

Nuclear Theory · Physics 2007-05-23 V. E. Oberacker , A. S. Umar , E. Teran

We have recently discussed an algorithm to automatically generate auxiliary basis sets (ABSs) of the standard form for density fitting (DF) or resolution-of-the-identity (RI) calculations in a given atomic orbital basis set (OBS) of any…

Computational Physics · Physics 2023-10-30 Susi Lehtola

The coupled cluster method (CCM) is employed to very high orders of approximation to study the ground-state (GS) properties of the spin-$s$ Heisenberg antiferromagnet (with isotropic interactions, all of equal strength, between…

Strongly Correlated Electrons · Physics 2016-03-02 R. F. Bishop , P. H. Y. Li

The critical behavior of the Ising model on a fractal lattice, which has the Hausdorff dimension $\log_{4} 12 \approx 1.792$, is investigated using a modified higher-order tensor renormalization group algorithm supplemented with automatic…

Statistical Mechanics · Physics 2023-03-22 Jozef Genzor

This paper develops a novel second order cone relaxation of the semidefinite programming formulation of optimal power flow, that does not imply the `angle relaxation'. We build on a technique developed by Kim et al., extend it for complex…

Optimization and Control · Mathematics 2021-04-15 Frederik Geth , James Foster

We want to propose a new discretization ansatz for the second order Hessian complex exploiting benefits of isogeometric analysis, namely the possibility of high-order convergence and smoothness of test functions. Although our approach is…

Numerical Analysis · Mathematics 2021-09-14 Jeremias Arf , Bernd Simeon

We present a density matrix approach for computing global solutions of Hartree-Fock theory, based on semidefinite programming (SDP), that gives upper and lower bounds on the Hartree-Fock energy of quantum systems. Equality of the upper- and…

Chemical Physics · Physics 2014-02-11 Srikant Veeraraghavan , David A. Mazziotti

We consider higher-order corrections to hyperfine coefficients related to the spin-orbit and spin-spin tensor interactions in hydrogen molecular ions. The $m\alpha^7 \ln(\alpha)$-order radiative correction is derived in the NRQED framework.…

Atomic Physics · Physics 2022-09-14 Mohammad Haidar , Vladimir I. Korobov , Laurent Hilico , Jean-Philippe Karr

The low-lying n(=3,4,5)d $^2D_{5/2}$ states alkaline earth ions are of vital importance in a number of different physical applications. The hyperfine structure constants of these states are characterized by unusually strong electron…

Atomic Physics · Physics 2015-06-26 B. K. Sahoo , C. Sur , T. Beier , B. P. Das , R. K. Chaudhuri , D. Mukherjee

Spin fluctuation-induced superconductivity in quasi-two dimensional organic compounds, \kappa-BEDT-TTF salts, is investigated within a fluctuation exchange (FLEX) approximation using a half-filled Hubbard model with a right-angled isosceles…

Superconductivity · Physics 2016-08-15 Hisashi Kondo , Tôru Moriya

We present a second-order formulation of multi-reference algebraic diagrammatic construction theory [Sokolov, A. Yu. J. Chem. Phys. 2018, 149, 204113] for simulating photoelectron spectra of strongly correlated systems (MR-ADC(2)). The…

Chemical Physics · Physics 2020-07-28 Koushik Chatterjee , Alexander Yu. Sokolov

We report a new analysis protocol for HCN hyperfine data, based on the PYSPECKIT package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars…

Astrophysics of Galaxies · Physics 2017-01-25 W. J. Schap , P. J. Barnes , A. Ordonez , A. Ginsburg , Y. Yonekura , Y. Fukui

Rigorous coupled-channel quantum scattering calculations on molecular collisions in external fields are computationally demanding due to the need to account for a large number of coupled channels and multiple total angular momenta $J$ of…

Chemical Physics · Physics 2019-05-01 Masato Morita , Timur V. Tscherbul

We present a new determination of the strong coupling constant $\alpha_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron…

High Energy Physics - Phenomenology · Physics 2026-03-18 Alim Ablat , Sayipjamal Dulat , Marco Guzzi , Joey Huston , Kirtimaan Mohan , Pavel Nadolsky , Dan Stump , C. -P. Yuan

We introduce an energy functional for ground-state electronic structure calculations. Its variables are the natural spin-orbitals of singlet many-body wave functions and their joint occupation probabilities deriving from controlled…

Chemical Physics · Physics 2016-12-04 Ralph Gebauer , Morrel H. Cohen , Roberto Car

We present a density matrix approach for computing global solutions of restricted open-shell Hartree-Fock theory, based on semidefinite programming (SDP), that gives upper and lower bounds on the Hartree-Fock energy of quantum systems.…

Chemical Physics · Physics 2014-04-22 Srikant Veeraraghavan , David A. Mazziotti

Standard numerical algorithms like the fast multipole method or $\mathcal{H}$-matrix schemes rely on low-rank approximations of the underlying kernel function. For high-frequency problems, the ranks grow rapidly as the mesh is refined, and…

Numerical Analysis · Mathematics 2017-06-20 Steffen Börm