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We study several approaches to orbital optimization in selected configuration interaction plus perturbation theory (SCI+PT) methods, and test them on the ground and excited states of three molecules using the semistochastic heatbath…

Chemical Physics · Physics 2021-07-14 Yuan Yao , C. J. Umrigar

Present atomic theory provides accurate and reliable results for atoms with a small number of valence electrons. However, most current methods of calculations fail when the number of valence electrons exceeds four or five. This means that…

Atomic Physics · Physics 2024-07-10 M. G. Kozlov , I. I. Tupitsyn , A. I. Bondarev , D. V. Mironova

Incremental full configuration interaction (iFCI) is polynomial-cost approach to the FCI limit of electronic structure. This article introduces the many-body basis set amelioration (MBBSA) method, which is designed to allow iFCI to be…

Chemical Physics · Physics 2025-03-12 Jeffrey P Hatch , Alan E Rask , Duy-Khoi Dang , Paul M Zimmerman

Multi-task reinforcement learning aims to quickly identify solutions for new tasks with minimal or no additional interaction with the environment. Generalized Policy Improvement (GPI) addresses this by combining a set of base policies to…

Machine Learning · Computer Science 2025-11-14 Lucas N. Alegre , Ana L. C. Bazzan , André Barreto , Bruno C. da Silva

We introduce and benchmark a systematically improvable route for excited-state calculations, state-specific configuration interaction ($\Delta$CI), \alert{which is a particular realization of multiconfigurational self-consistent field and…

Chemical Physics · Physics 2023-08-31 Fábris Kossoski , Pierre-François Loos

Modern software systems are usually highly configurable, providing users with customized functionality through various configuration options. Understanding how system performance varies with different option combinations is important to…

Software Engineering · Computer Science 2022-04-11 Jiezhu Cheng , Cuiyun Gao , Zibin Zheng

We present a quantum-classical hybrid algorithm for calculating the ground state and its energy of the quantum many-body Hamiltonian by proposing an adaptive construction of a quantum state for the quantum-selected configuration interaction…

Quantum Physics · Physics 2024-12-12 Yuya O. Nakagawa , Masahiko Kamoshita , Wataru Mizukami , Shotaro Sudo , Yu-ya Ohnishi

Although self-consistent multi-configuration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. This work aims at…

Nuclear Theory · Physics 2016-02-02 C. Robin , N. Pillet , D. Peña Arteaga , J. -F. Berger

Recent advances in selected CI, including the adaptive sampling configuration interaction (ASCI) algorithm and its heat bath extension, have made the ASCI approach competitive with the most accurate techniques available, and hence an…

To develop, analyze, and evolve today's highly configurable software systems, developers need deep knowledge of a system's configuration options, e.g., how options need to be set to reach certain locations, what configurations to use for…

Software Engineering · Computer Science 2019-04-01 ThanhVu Nguyen , Ugur Koc , Javran Cheng , Jeffrey S. Foster , Adam A. Porter

In this work, we report an algorithm that is able to tailor qubit interactions for individual variational quantum algorithm problems. Here, the algorithm leverages the unique ability of a neutral atom tweezer platform to realize arbitrary…

Quantum Physics · Physics 2026-03-04 Robert de Keijzer , Luke Visser , Oliver Tse , Servaas Kokkelmans

The formalism based on correlated basis functions and the cluster expansion technique has been recently employed to derive an effective interaction from a realistic nuclear hamiltonian. To gauge the reliability of this scheme, we perform a…

Nuclear Theory · Physics 2015-08-17 Angela Mecca , Alessandro Lovato , Omar Benhar , Artur Polls

The fast Ewald methods are widely used to compute the point-charge electrostatic interactions in molecular simulations. The key step that introduces errors in the computation is the particle-mesh interpolation. In this work, the optimal…

Chemical Physics · Physics 2017-10-25 Han Wang , Jun Fang , Xingyu Gao

Reliable theoretical predictions of nuclear dipole excitations are crucial for various nuclear applications, particularly in nuclear astrophysics. Calculations of radiative capture cross sections often rely on theoretical gamma strength…

Nuclear Theory · Physics 2025-12-10 O. Le Noan , K. Sieja

Neutral uranium (U I) is a very difficult atom for theoretical calculations due to a large number of valence electrons, six, strong valence-valence and valence-core correlations, high density of states, and relativistic effects.…

Atomic Physics · Physics 2020-10-14 Igor M. Savukov

Long-range interactions are essential determinants of chemical system behaviour across diverse environments. We present a foundation framework that integrates explicit polarizable long-range physics with an equivariant graph neural network…

Chemical Physics · Physics 2025-11-27 Rongzhi Gao , ChiYung Yam , Jianjun Mao , Shuguang Chen , GuanHua Chen , Ziyang Hu

We describe a number of recently developed techniques for improving the performance of large-scale nuclear configuration interaction calculations on high performance parallel computers. We show the benefit of using a preconditioned block…

Numerical Analysis · Computer Science 2017-12-29 Meiyue Shao , Hasan Metin Aktulga , Chao Yang , Esmond G. Ng , Pieter Maris , James P. Vary

We formulate statistical-mechanical inverse methods in order to determine optimized interparticle interactions that spontaneously produce target many-particle configurations. Motivated by advances that give experimentalists greater and…

Soft Condensed Matter · Physics 2007-05-23 Mikael C. Rechtsman , Salvatore Torquato , Frank H. Stillinger

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

Quantum-selected configuration interaction (QSCI) is a novel quantum-classical hybrid algorithm for quantum chemistry calculations. This method identifies electron configurations having large weights for the target state using quantum…

Chemical Physics · Physics 2025-03-31 Soichi Shirai , Shih-Yen Tseng , Hokuto Iwakiri , Takahiro Horiba , Hirotoshi Hirai , Sho Koh