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The purpose of this letter is to show that a rotation of Hartree-Fock canonical orbitals which minimizes the lowest eigenvalues of a configuration interaction calculation limited to the mono-excitated configurations from a given orbital…

Chemical Physics · Physics 2007-12-05 Patrick Cassam-Chenaï , Giovanni Granucci

We present an open-shell frozen natural orbital (FNO) approach, which utilizes the second-order Z-averaged perturbation theory (ZAPT2), to reduce the restricted opten-shell Hartree-Fock virtual space size with controllable accuracy. Our…

Chemical Physics · Physics 2026-04-17 Angela F. Harper , Xiaobing Liu , Scott N. Genin , Ilya G. Ryabinkin

The complete active space self-consistent field (CASSCF) method is the principal approach employed for studying strongly correlated systems. However, exact CASSCF can only be performed on small active spaces of ~20 electrons in ~20 orbitals…

Computational Physics · Physics 2021-12-22 Daniel S. Levine , Diptarka Hait , Norm M. Tubman , Susi Lehtola , K. Birgitta Whaley , Martin Head-Gordon

The ground states of the two-dimensional repulsive Hubbard model are studied within the unrestricted Hartree-Fock (UHF) theory. Magnetic and charge properties are determined by systematic, large-scale, exact numerical calculations, and…

Strongly Correlated Electrons · Physics 2013-09-20 Jie Xu , Chia-Chen Chang , Eric J. Walter , Shiwei Zhang

HF-DFT, the practice of evaluating approximate density functionals on Hartree-Fock densities, has long been used in testing density functional approximations. Density-corrected DFT (DC-DFT) is a general theoretical framework for identifying…

Chemical Physics · Physics 2021-10-18 Suhwan Song , Stefan Vuckovic , Eunji Sim , Kieron Burke

Donor-based quantum devices in silicon are attractive platforms for universal quantum computing and analog quantum simulations. The nearly-atomic precision in dopant placement promises great control over the quantum properties of these…

Quantum Physics · Physics 2025-03-05 Maicol A. Ochoa , Keyi Liu , Piotr Różański , Michał Zieliński , Garnett W. Bryant

The self-consistent field method utilized for solving the Hartree-Fock (HF) problem and the closely related Kohn-Sham problem, is typically thought of as one of the cheapest methods available to quantum chemists. This intuition has been…

Quantum Physics · Physics 2015-06-22 James D. Whitfield , Zoltán Zimborás

Given a set of Kohn-Sham orbitals from an insulating system, we present a simple, robust, efficient and highly parallelizable method to construct a set of, optionally orthogonal, localized basis functions for the associated subspace. Our…

Computational Physics · Physics 2014-11-05 Anil Damle , Lin Lin , Lexing Ying

In periodic systems, the Hartree-Fock (HF) exchange energy exhibits the slowest convergence of all HF energy components as the system size approaches the thermodynamic limit. We demonstrate that the recently proposed staggered mesh method…

Computational Physics · Physics 2024-02-22 Stephen Jon Quiton , Hamlin Wu , Xin Xing , Lin Lin , Martin Head-Gordon

We present low-scaling algorithms for $GW$ and constrained random phase approximation based on a symmetry-adapted interpolative separable density fitting (ISDF) procedure that incorporates the space-group symmetries of crystalline systems.…

Materials Science · Physics 2024-01-24 Chia-Nan Yeh , Miguel A. Morales

We formulate an ab initio downfolding scheme for electron-phonon coupled systems. In this scheme, we calculate partially renormalized phonon frequencies and electron-phonon coupling, which include the screening effects of high-energy…

Strongly Correlated Electrons · Physics 2015-12-10 Yusuke Nomura , Ryotaro Arita

The structure of approximate two electron wavefunction is deeply investigated, both theoretically and numerically, in the strong-field driven ionization dynamics. Theoretical analyses clarify that for two electron singlet systems, the…

Atomic Physics · Physics 2014-11-13 Takeshi Sato , Kenichi L Ishikawa

The current work presents a natural orbital functional (NOF) for electronic systems with any spin value independent of the external potential being considered, that is, a global NOF (GNOF). It is based on a new two-index reconstruction of…

Chemical Physics · Physics 2021-12-07 Mario Piris

Asymmetric nuclear matter is investigated in the low density region below the nuclear saturation density. Microscopic calculations based on the Dirac Brueckner Hartree-Fock (DBHF) approach with realistic nucleon-nucleon potentials are used…

Nuclear Theory · Physics 2008-11-26 J. Margueron , E. Van Dalen , C. Fuchs

High current storage rings, such as the Z-pole operating mode of the FCC-ee, require accelerating cavities that are optimized with respect to both the fundamental mode and the higher order modes. Furthermore, the cavity shape needs to be…

Accelerator Physics · Physics 2020-01-01 Marija Kranjcevic , Shahnam Gorgi Zadeh , Andreas Adelmann , Peter Arbenz , Ursula van Rienen

We introduce the first multiorbital effective tight-binding model to describe the effect of electron-electron interactions in this system. Upon fixing all the effective hopping parameters in the normal state against an ab initio band…

Strongly Correlated Electrons · Physics 2017-06-27 Lei Su , Chuang-Han Hsu , Hsin Lin , Vitor M. Pereira

In this paper, the CONFIG algorithm, a simple and provably efficient constrained global optimization algorithm, is applied to optimize the closed-loop control performance of an unknown system with unmodeled constraints. Existing Gaussian…

Optimization and Control · Mathematics 2022-12-20 Wenjie Xu , Yuning Jiang , Bratislav Svetozarevic , Colin N. Jones

We have investigated the electronic structure of rare-earth tetraborides, $\textrm{RB}_{4}$, using first-principle electronic structure methods (DFT) implemented in Quantum Espresso (QE). In this article we have studied heather-to neglected…

Strongly Correlated Electrons · Physics 2023-03-22 Ismail Sk , Nandan Pakhira

This is extended version of a previously submitted paper, in which special solutions of the Hartree-Fock (HF) problem for Coulomb interacting electrons, being described by a simple model of the Cu-O planes in La2CuO4, are presented. One of…

Strongly Correlated Electrons · Physics 2009-02-26 Alejandro Cabo-Bizet , Alejandro Cabo-Montes de Oca

Singlet fission (SF) is an electronic transition that in the last decade has been under the spotlight for its applications in optoelectronics, from photovoltaics to spintronics. Despite considerable experimental and theoretical…

Quantum Physics · Physics 2024-11-12 Francesco Campaioli , Alice Pagano , Daniel Jaschke , Simone Montangero