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We consider a spacecraft formation reconfiguration problem in the case of identical spacecraft. This introduces in the optimal reconfiguration problem a permutational degree of freedom, in addition to the choice of individual spacecraft…

Optimization and Control · Mathematics 2007-05-23 Taeyoung Lee , N. Harris McClamroch , Melvin Leok

For many-body methods such as MCSCF and CASSCF, in which the number of one-electron orbitals are optimized and independent of basis set used, there are no problems with using plane-wave basis sets. However, for methods currently used in…

Computational Physics · Physics 2020-09-02 Eric J. Bylaska , Duo Song , Nicholas P. Bauman , Karol Kowalski , Daniel Claudino , Travis S. Humble

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…

It has recently been shown that the SOiCI approach [J. Phys.: Condens. Matter 34 (2022) 224007], in conjunction with the spin-separated exact two-component relativistic Hamiltonian, can provide very accurate fine structures of systems…

Chemical Physics · Physics 2023-07-18 Yang Guo , Ning Zhang , Wenjian Liu

In this paper we present a computational procedure that utilizes real-space grids to obtain high precision approximations of electrostatically confined few-electron states such as those that arise in gated semiconductor quantum dots. We use…

Mesoscale and Nanoscale Physics · Physics 2023-01-27 Christopher R. Anderson , Mark F. Gyure , Sam Quinn , Andrew Pan , Richard S. Ross , Andrey A. Kiselev

Although selected configuration interaction (SCI) algorithms can tackle much larger Hilbert spaces than the conventional full CI (FCI) method, the scaling of their computational cost with respect to the system size remains inherently…

Chemical Physics · Physics 2024-12-02 Abdallah Ammar , Anthony Scemama , Pierre-François Loos , Emmanuel Giner

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

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)…

Reduced density matrix functional theory (RDMFT) calculations are usually implemented in a decoupled manner, where the orbital and occupation optimizations are repeated alternately. Typically, orbital updates are performed using the unitary…

Chemical Physics · Physics 2024-09-04 Yi-Fan Yao , Neil Qiang Su

We investigate the performance of a class of compact and systematically improvable Jastrow-Slater wave functions for the efficient and accurate computation of structural properties, where the determinantal component is expanded with a…

Chemical Physics · Physics 2019-01-17 Monika Dash , Saverio Moroni , Anthony Scemama , Claudia Filippi

The Perdew-Zunger (PZ) method provides a way to remove the self-interaction (SI) error from density functional approximations on an orbital by orbital basis. The PZ method provides significant improvements for the properties such as barrier…

Chemical Physics · Physics 2020-05-20 Yoh Yamamoto , Selim Romero , Tunna Baruah , Rajendra R. Zope

We identify and rectify a crucial source of bias in the initiator FCIQMC algorithm. Non-initiator determinants (i.e. determinants whose population is below the initiator threshold) are subject to a systematic {\em undersampling} bias, which…

Computational Physics · Physics 2019-12-13 Khaldoon Ghanem , Alexander Y. Lozovoi , Ali Alavi

We extend our recently-developed heat-bath configuration interaction (HCI) algorithm, and our semistochastic algorithm for performing multireference perturbation theory, to the calculation of excited-state wavefunctions and energies. We…

Strongly Correlated Electrons · Physics 2017-11-22 Adam A. Holmes , C. J. Umrigar , Sandeep Sharma

Approximate natural orbitals are investigated as a way to improve a Monte Carlo configuration interaction (MCCI) calculation. We introduce a way to approximate the natural orbitals in MCCI and test these and approximate natural orbitals…

Chemical Physics · Physics 2013-04-12 J. P. Coe , M. J. Paterson

Full Configuration Interaction Quantum Monte Carlo (FCIQMC) has been effectively applied to very large configuration interaction (CI) problems, and was recently adapted for use as an active space solver and combined with orbital…

Chemical Physics · Physics 2020-02-19 Robert J. Anderson , Toru Shiozaki , George H. Booth

It has recently been shown that configuration state functions (CSF) with local orbitals can provide a compact reference state for low-spin open-shell electronic structures, such as antiferromagnetic states. However, optimizing a low-spin…

Chemical Physics · Physics 2025-08-05 Hugh G. A. Burton

The Full Configuration Interaction Quantum Monte Carlo (FCIQMC) method has proved able to provide near-exact solutions to the electronic Schr\"odinger equation within a finite orbital basis set, without relying on an expansion about a…

Computational Physics · Physics 2016-08-24 Jennifer Kersten , George H. Booth , Ali Alavi

This paper presents a continuous optimization approach to DCOC and its application to spacecraft high-precision attitude control. The approach computes a control input sequence that maximizes the time-before-exit by solving a nonlinear…

Optimization and Control · Mathematics 2021-12-23 Sunbochen Tang , Nan Li , Robert A. E. Zidek , Ilya Kolmanovsky

We present the One-orbital Ensemble Self-Consistent Field (OE-SCF) method, an {alternative} orbital-free DFT solver that extends the applicability of DFT to system sizes beyond the nanoscale while retaining the accuracy required to be…

Materials Science · Physics 2021-05-05 Xuecheng Shao , Wenhui Mi , Michele Pavanello

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