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The Configuration Interaction (CI) method using orbitals centered on the nucleus has recently been applied to calculate the interactions of positrons interacting with atoms. Computational investigations of the convergence properties of…

Atomic Physics · Physics 2007-05-23 J. Mitroy , M. W. J. Bromley

In a previous work (arXiv:2010.02027) we showed how the full configuration interaction (FCI) ground state energy can be obtained as a functional of an arbitrary reference wavefunction by means of a gradient descent or quasi-Newton…

Chemical Physics · Physics 2020-12-10 Carlos A. Jiménez-Hoyos

Traditional multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) methods are based on a single orthonormal orbital basis (OB). For atoms with complicated shell structures, a large OB is needed to saturate all the…

Atomic Physics · Physics 2015-06-12 S. Verdebout , P. Rynkun , P. Jönsson , G. Gaigalas , C. Froese Fischer , M. Godefroid

Selected configuration interaction (SCI) methods have emerged as state-of-the-art methodologies for achieving high accuracy and generating benchmark reference data for ground and excited states in small molecular systems. However, their…

Chemical Physics · Physics 2024-06-13 Hugh G. A. Burton , Pierre-François Loos

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

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 configuration interaction (CI) framework which serves quantitative and conceptual purposes for charge delocalization and electron transfer processes in molecular systems. The electronic Hamiltonian is expressed in a basis of…

Chemical Physics · Physics 2025-09-09 Sarai Dery Folkestad , Ida-Marie Høyvik

Configuration Interaction (CI) calculations on the ground state of the C atom are carried out using a small basis set of Slater orbitals [7s6p5d4f3g]. The configurations are selected according to their contribution to the total energy. One…

Atomic Physics · Physics 2017-08-01 María Belén Ruiz , Robert Tröger

Full configuration interaction (FCI) solvers are limited to small basis sets due to their expensive computational costs. An optimal orbital selection for FCI (OptOrbFCI) is proposed to boost the power of existing FCI solvers to pursue the…

Chemical Physics · Physics 2020-09-01 Yingzhou Li , Jianfeng Lu

The Projected Configuration Interaction (PCI) method starts from a collection of mean-field wave functions, and builds up correlated wave functions of good symmetry. It relies on the Generator Coordinator Method (GCM) techniques, but it…

Nuclear Theory · Physics 2009-02-18 Zaochun Gao , Mihai Horoi

Hierarchy configuration interaction (hCI) has been recently introduced as an alternative configuration interaction (CI) route combining excitation degree and seniority number, which showed to efficiently recover both dynamic and static…

Chemical Physics · Physics 2024-02-20 Fábris Kossoski , Pierre-François Loos

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)…

We consider gradient descent and quasi-Newton algorithms to optimize the full configuration interaction (FCI) ground state wavefunction starting from an arbitrary reference state $|0 \rangle$. We show that the energies obtained along the…

Chemical Physics · Physics 2021-02-03 Carlos A. Jiménez-Hoyos

Spin-orbit coupling (SOC) drives interesting and non-trivial phenomena in solid state physics, ranging from topological to magnetic to transport properties. Thorough study of such phenomena often require effective models where SOC term is…

Materials Science · Physics 2024-07-09 Qiangqiang Gu , Shishir Kumar Pandey

We describe in detail a full configuration interaction (CI) method designed to analyze systems of quantum dots. This method is capable of exploring large regions of parameter space, like more approximate approaches such as Heitler London…

Mesoscale and Nanoscale Physics · Physics 2010-06-15 Erik Nielsen , Richard P. Muller

Accurate calculations of strongly correlated materials remain a formidable challenge in condensed matter physics, particularly due to the computational demand of conventional methods. This paper presents an efficient solver for dynamical…

Strongly Correlated Electrons · Physics 2025-12-04 Basile Herzog , Patrik Thunström , Olle Eriksson

The combinatorial scaling of configuration interaction (CI) has long restricted its applicability to only the simplest molecular systems. Here, we report the first numerically exact CI calculation exceeding one quadrillion ($10^{15}$)…

Chemical Physics · Physics 2025-12-16 Agam Shayit , Can Liao , Shiv Upadhyay , Hang Hu , Tianyuan Zhang , Eugene DePrince , Chao Yang , Xiaosong Li

A version of the configuration interaction (CI) method is developed which treats highly excited many-electron basis states perturbatively, so that their inclusion does not affect the size of the CI matrix. This removes, at least in…

Atomic Physics · Physics 2017-01-25 V. A. Dzuba , J. Berengut , C. Harabati , V. V. Flambaum

Methods for correcting residual energy errors of configuration interaction (CI) calculations of molecules and other electronic systems are discussed based on the assumption that the energy defect can be mapped onto atomic regions. The…

Chemical Physics · Physics 2022-10-05 Jerry L. Whitten

In this work, we develop a mathematical framework for a Selected Configuration Interaction (SCI) algorithm within a bi-orthogonal basis for transcorrelated (TC) calculations. The bi-orthogonal basis used here serves as the equivalent of the…

Chemical Physics · Physics 2023-06-22 Abdallah Ammar , Anthony Scemama , Emmanuel Giner