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In this paper, we propose a generic and systematic approach for study of the electronic structure for atoms or molecules. In particular, we address the issue of single particle states, or orbitals, which should be one of the most important…

Chemical Physics · Physics 2007-05-23 Liqiang Wei

We have developed a couple of optimal damping algorithms (ODAs) for unrestricted Hartree-Fock (UHF) calculations of open-shell molecular systems. A series of equations were derived for both concurrent and alternate constructions of alpha-…

Chemical Physics · Physics 2018-01-25 Jun-ichi Yamamoto , Yuji Mochizuki

The usual Hartree-Fock approximation to the Hubbard model is based on eigenstates of the electron number operator. But this formulation is not unique. A different (and inequivalent) version, formulated in terms of Nambu two-component…

Strongly Correlated Electrons · Physics 2024-09-04 Kazue Matsuyama , Jeff Greensite

New local "hybrid" functionals proposed by V. V. Karasiev in [J. Chem. Phys. {\bf 118}, 8567 (2003)] are benchmarked against nonlocal hybrid functionals. Their performance is tested on the total and high occupied orbital energies, as well…

Chemical Physics · Physics 2012-10-26 Ivan A. Mikhailov , Olga A. Shukruto , Artem E. Masunov , Valentin V. Karasiev

Energy barriers, which control the rates of chemical reactions, are seriously underestimated by computationally-efficient semi-local approximations for the exchange-correlation energy. The accuracy of a semi-local density functional…

Chemical Physics · Physics 2023-11-06 Bikash Kanungo , Aaron D. Kaplan , Chandra Shahi , Vikram Gavini , John P. Perdew

The time-dependent Hartree-Fock (TDHF) method is an approach to simulate the mean field dynamics of electrons within the assumption that the electrons move independently in their self-consistent average field and within the space of single…

Quantum Physics · Physics 2023-09-06 Sahil Gulania , Stephen K. Gray , Yuri Alexeev , Bo Peng , Niranjan Govind

We present a symmetry projection technique for enforcing rotational and parity symmetries in nuclear-electronic Hartree-Fock wave functions, which treat electrons and nuclei on equal footing. The molecular Hamiltonian obeys rotational and…

Chemical Physics · Physics 2023-11-03 Robin Feldmann , Alberto Baiardi , Markus Reiher

This paper introduces and analyses the new grid-based tensor approach for approximate solution of the eigenvalue problem for linearized Hartree-Fock equation applied to the 3D lattice-structured and periodic systems. The set of localized…

Numerical Analysis · Mathematics 2014-08-19 Venera Khoromskaia , Boris N. Khoromskij

Separating the Coulomb potential into short-range and long-range components enables the use of different electron repulsion integral algorithms for each component. The short-range part can be efficiently computed using the analytical…

Chemical Physics · Physics 2023-09-27 Qiming Sun

This paper reports an implementation of Hartree-Fock linear response with complex orbitals for computing electronic spectra of molecules in a strong external magnetic fields. The implementation is completely general, allowing for…

Chemical Physics · Physics 2019-02-01 Sangita Sen , Kai K. Lange , Erik I. Tellgren

The general procedure underlying Hartree-Fock and Kohn-Sham density functional theory calculations consists in optimizing orbitals for a self-consistent solution of the Roothaan-Hall equations in an iterative process. It is often ignored…

Chemical Physics · Physics 2017-03-16 Alain C. Vaucher , Markus Reiher

Hartree-Fock-Bogolyubov solutions corresponding to the tetrahedral deformation are found in six tetrahedrally doubly-magic nuclei. Values of the beta32 deformation, depths of the tetrahedral minima, and their energies relative to the…

Nuclear Theory · Physics 2009-11-11 P. Olbratowski , J. Dobaczewski , P. Powałowski , M. Sadziak , K. Zberecki

Electromagnetic and weak transitions tell us a great deal about the structure of atomic nuclei. Yet modeling transitions can be difficult: it is often easier to compute the ground state, if only as an approximation, than excited states. One…

Nuclear Theory · Physics 2020-09-21 Calvin W. Johnson , Ken A. Luu , Yi Lu

We explore the impact of optimizations of the single-particle basis on the convergence behavior and robustness of ab initio no-core shell model calculations. Our focus is on novel basis sets defined by the natural orbitals of a correlated…

Nuclear Theory · Physics 2019-03-27 Alexander Tichai , Julius Müller , Klaus Vobig , Robert Roth

Hartree Fock equations for finite range interactions in a slab of nuclear matter are presented and solved using an algorithm based on the Lagrange mesh method. This approach is faster and more efficient than the Numerov algorithm commonly…

Nuclear Theory · Physics 2025-11-13 Dany Davesne , Alessandro Pastore , Jesus Navarro

We present a new hybrid method to solve the relativistic Hartree-Fock-Roothan equations where the one- and two-electron radial integrals are evaluated numerically by defining the basis functions on a grid. This procedure reduces the…

Atomic Physics · Physics 2009-10-31 Rajat K. Chaudhuri , Prafulla K. Panda , B. P. Das

The crucial step in density-corrected Hartree-Fock density functional theory (DC(HF)-DFT) is to decide whether the density produced by the density functional for a specific calculation is erroneous and hence should be replaced by, in this…

Chemical Physics · Physics 2023-09-20 Daniel Graf , Alex J. W. Thom

A previously proposed computational procedure for constructing a set of nonorthogonal strongly localised one-electron molecular orbitals (O. Danyliv, L. Kantorovich - physics/0401107) is applied to a perfect $\alpha$-quartz crystal…

Chemical Physics · Physics 2009-11-10 Oleh Danyliv , Lev Kantorovich

We use the multiconfiguration Dirac-Hartree-Fock (MCDHF) method combined with the relativistic configuration interaction (RCI) approach (GRASP2K) to provide a consistent set of transition energies and radiative transition data for the lower…

Atomic Physics · Physics 2020-01-08 K. Wang , P. Jönsson , G. Del Zanna , M. Godefroid , Z. B. Chen , C. Y. Chen , J. Yan

Fractional-spin errors are inherent in all current approximate density functionals, including Hartree-Fock theory, and their origin has been related to strong static correlation effects. The conventional way to encode fractional-spin…

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