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We present an efficient implementation of the second-order two-component relativistic core-valence-separated algebraic diagrammatic construction method (CVS-ADC(2)) for core-excitation calculations. The approach employs state-averaged…

Chemical Physics · Physics 2026-05-01 Somesh Chamoli , Sudipta Chakraborty , Xubo Wang , Achintya Kumar Dutta

We report in this paper an implementation of 4-component relativistic Hamiltonian based Equation-of-Motion Coupled-Cluster with singles and doubles (EOM-CCSD) theory for the calculation of ionization potential (IP), electron affinity (EA)…

Chemical Physics · Physics 2018-11-09 Avijit Shee , Trond Saue , Lucas Visscher , Andre Severo Pereira Gomes

In view of immense interest to understand impact of an electron on atoms in the low-energy scattering phenomena observed in laboratories and astrophysical processes, we prescribe here an approach to construct potentials using relativistic…

Atomic Physics · Physics 2022-09-02 B. K. Sahoo

In this paper we show that 1-electron properties such as Compton profiles and structure factors of crystals can be asymptotically retrieved through cluster-based calculations, followed by an appropriate partition of the 1-electron reduced…

Chemical Physics · Physics 2015-06-26 Sebastien Ragot , Jean-Michel Gillet , Pierre J Becker

A method and codes for two-step correlation calculation of heavy-atom molecules have been developed, employing the generalized relativistic effective core potential and relativistic coupled cluster (RCC) methods at the first step, followed…

Chemical Physics · Physics 2009-11-07 A. N. Petrov , N. S. Mosyagin , T. A. Isaev , A. V. Titov , V. F. Ezhov , E. Eliav , U. Kaldor

Fe-Co alloys with induced tetragonal strain are promising materials for rare-earth-free permanent magnets. However, as ultrathin-film studies have shown, tetragonal Fe-Co structures tend to a rapid relaxation toward a cubic structure as the…

Materials Science · Physics 2025-02-10 Wojciech Marciniak , Mirosław Werwiński

Excited-state electronic structure in strongly correlated systems remains challenging due to the exponential scaling of the many-body Hilbert space and the difficulty of constructing systematically controlled active spaces. Building on the…

Chemical Physics · Physics 2026-05-05 Annabelle Canestraight , Russell Miller , Libor Veis , Vojtech Vlcek

Determination of nuclear moments for many nuclei relies on the computation of hyperfine constants, with theoretical uncertainties directly affecting the resulting uncertainties of the nuclear moments. In this work we improve the precision…

Atomic Physics · Physics 2022-01-05 S. G. Porsev , M. S. Safronova , M. G. Kozlov

First-principles, density-functional based electronic structure calculations are carried out for MgC(Ni_{1-x}Co_{x})_{3} alloys over the concentration range 0\leq x\leq1, using Korringa-Kohn-Rostoker coherent-potential approximation (KKR…

Materials Science · Physics 2009-11-11 P. Jiji Thomas Joseph , Prabhakar P. Singh

The coupled cluster method (CCM) has previously been applied to study the ground- and excited-state properties of many different types of frustrated and unfrustrated quantum spin systems. A common feature in the application of the CCM is to…

Strongly Correlated Electrons · Physics 2014-02-20 Damian J. J. Farnell , Andrew I. Croudace

A method is presented to calculate from first principles the higher-order elastic constants of a solid material. The method relies on finite strain deformations, a density functional theory approach to calculate the Cauchy stress tensor,…

Materials Science · Physics 2025-10-08 Ruvini Attanayake , Umesh C. Roy , Abhiyan Pandit , Angelo Bongiorno

The atomic cluster expansion (ACE) efficiently parameterizes complex energy surfaces of pure elements and alloys. Due to the local nature of the many-body basis, ACE is inherently local or semilocal for graph ACE. Here, we employ…

Materials Science · Physics 2024-11-07 Matteo Rinaldi , Anton Bochkarev , Yury Lysogorskiy , Ralf Drautz

A Magnetic Cluster Expansion (MCE) model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed using DFT data spanning binary and ternary alloy configurations. Using this MCE model Hamiltonian, we perform Monte Carlo…

Materials Science · Physics 2016-11-24 M. Y. Lavrentiev , J. S. Wróbel , D. Nguyen-Manh , S. L. Dudarev , M. G. Ganchenkova

We present an efficient algorithm for one- and two-component relativistic exact-decoupling calculations. Spin-orbit coupling is thus taken into account for the evaluation of relativistically transformed (one-electron) Hamiltonian. As the…

Chemical Physics · Physics 2013-05-10 Daoling Peng , Nils Middendorf , Florian Weigend , Markus Reiher

Regge-pole calculated low-energy electron elastic total cross sections (TCSs) for complex heavy atoms and fullerene molecules are characterized generally by ground, metastable, and excited negative-ion formation, shape resonances and…

Atomic and Molecular Clusters · Physics 2021-11-09 Zineb Felfli , Alfred Z. Msezane

In this communication we have studied the electronic structure, magnetic and optical properties of bcc \fecr alloys in the ferromagnetic phase. We have used the augmented space recursion technique coupled with tight-binding linearized…

Disordered Systems and Neural Networks · Physics 2007-06-12 Kartick Tarafder , Atisdipankar Chakrabarti , Subhradip Ghosh , Biplab Sanyal , Olle Eriksson , Abhijit Mookerjee

A relativistic coupled-cluster (RCC) theory is implemented to study electron impact excitations of atomic species. As a test case, the electron impact excitations of the $3s ~ ^2S_{1/2} - 3p ~ ^2P_{1/2;3/2}$ resonance transitions are…

Atomic Physics · Physics 2018-02-14 L. Sharma , B. K. Sahoo , P. Malkar , R. Srivastava

The coupled cluster method has been applied to the eigenvalue problem lattice Hamiltonian QCD (without quarks) for SU(2) gauge fields in two space dimensions. Using a recently presented new formulation and the truncation prescription of Guo…

High Energy Physics - Lattice · Physics 2007-05-23 D. Schuette , A. Wichmann , C. Weichmann

An experimental platform of ultralow-temperature pulsed ENDOR (electron-nuclear double resonance) spectroscopy is constructed for the bulk materials. Coherent property of the coupled electron and nuclear spins of the rare-earth (RE) dopants…

Recent developments of high-order CCM have been to extend existing formalism and codes to $s \ge \frac 12$ for both the ground and excited states. In this article, we describe how "generalised" expectation values for a wide range of one-…

Strongly Correlated Electrons · Physics 2009-11-30 D. J. J. Farnell