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The energy levels of the first few low-lying states of helium and lithium atoms in intense magnetic fields up to $\approx 10^8-10^9$~T are calculated in this study. A pseudospectral method is employed for the computational procedure. The…

Quantum Physics · Physics 2014-06-11 Anand Thirumalai , Jeremy S. Heyl

The development of reliable ab initio methods for light-matter strong coupling is necessary for a deeper understanding of molecular polaritons. The recently developed strong coupling quantum electrodynamics Hartree-Fock model (SC-QED-HF)…

Chemical Physics · Physics 2025-02-21 Matteo Castagnola , Rosario R. Riso , Yassir El Moutaoukal , Enrico Ronca , Henrik Koch

The current work presents a new single-reference method for capturing at the same time the static and dynamic electron correlation. The starting-point is a determinant wavefunction formed with natural orbitals obtained from a new…

Chemical Physics · Physics 2017-08-16 Mario Piris

We introduce a microscopic approach for calculating the excitation energies of systems formed during heavy-ion collisions. The method is based on time-dependent Hartree-Fock (TDHF) theory and allows the study of the excitation energy as a…

Nuclear Theory · Physics 2009-10-29 A. S. Umar , V. E. Oberacker , J. A. Maruhn , P. -G. Reinhard

A method for constructing semianalytical strongly correlated wave functions for single and molecular quantum dots is presented. It employs a two-step approach of symmetry breaking at the Hartree-Fock level and of subsequent restoration of…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Constantine Yannouleas , Uzi Landman

We discuss two problems which are particularly challenging for approximations in time-dependent density functional theory (TDDFT) to capture: momentum-distributions in ionization processes, and memory-dependence in real-time dynamics. We…

Materials Science · Physics 2010-03-22 Arun K. Rajam , Paul Hessler , Christian Gaun , Neepa T. Maitra

Extending density functional theory (DFT) to an {\it ab initio} orbital functional theory (OFT) requires new methodology for nonlocal exchange and correlation potentials. This paper describes such modifications to a standard Dirac-Slater…

Condensed Matter · Physics 2007-05-23 R. K. Nesbet

We apply in a schematic model a theory beyond mean-field, namely Stochastic Time-Dependent Hartree-Fock (STDHF), which includes dynamical electron-electron collisions on top of an incoherent ensemble of mean-field states by occasional…

Atomic and Molecular Clusters · Physics 2016-10-12 Lionel Lacombe , Paul-Gerhard Reinhard , Eric Suraud , Phuong Mai Dinh

The accurate description of the non-linear response of many-electron systems to strong-laser fields remains a major challenge. Methods that bypass the unfavorable exponential scaling with particle number are required to address larger…

A recent interpretation of the caloric curve based on the expansion of the abraded spectator nucleus is re-analysed in the framework of the Time-Dependent Hartree-Fock (TDHF) evolution. It is shown that the TDHF dynamics is more complex…

Nuclear Theory · Physics 2016-09-08 D. Lacroix , Ph. Chomaz

We provide a discussion of issues related to the center-of-mass motion and cross-channel coupling in applications of the time-dependent Hartree-Fock (TDHF) theory to heavy-ion collisions. We find that the entrance channel dynamics of a…

Nuclear Theory · Physics 2008-12-18 A. S. Umar , V. E. Oberacker

Calculating highly accurate thermochemical properties of condensed matter via wave function-based approaches (such as e.g. Hartree-Fock or hybrid functionals) has recently attracted much interest. We here present two strategies providing…

It was recently shown [Phys. Rev. Lett. 105, 123002 (2010)] that the complete wavefunction for a system of electrons and nuclei evolving in a time-dependent external potential can be exactly factorized into an electronic wavefunction and a…

Chemical Physics · Physics 2015-06-11 Ali Abedi , Neepa T. Maitra , E. K. U. Gross

These lecture notes are addressed to PhD student and/or researchers who want a general overview of microscopic approaches based on mean-field and applied to nuclear dynamics. Our goal is to provide a good description of low energy heavy-ion…

Nuclear Theory · Physics 2009-04-20 Cédric Simenel , Benoît Avez , Denis Lacroix

Deep neural networks have become a highly accurate and powerful wavefunction ansatz in combination with variational Monte Carlo methods for solving the electronic Schr\"odinger equation. However, despite their success and favorable scaling,…

Computational Physics · Physics 2023-03-20 Michael Scherbela , Leon Gerard , Philipp Grohs

The influence of inner electrons on the ionization dynamics in strong laser fields is investigated in a wavelength regime where the inner electron dynamics is usually assumed to be negligible. The role of inner electrons is of particular…

Atomic Physics · Physics 2014-03-11 J. Rapp , D. Bauer

We introduce an energy functional for ground-state electronic structure calculations. Its variables are the natural spin-orbitals of singlet many-body wave functions and their joint occupation probabilities deriving from controlled…

Chemical Physics · Physics 2016-12-04 Ralph Gebauer , Morrel H. Cohen , Roberto Car

It has been known that the time-dependent Hartree-Fock (TDHF) method, or the time-dependent density functional theory (TDDFT), fails to describe many-body quantum tunneling. We overcome this problem by superposing a few time-dependent…

Nuclear Theory · Physics 2020-06-15 N. Hasegawa , K. Hagino , Y. Tanimura

We discuss possible avenues to study fission dynamics starting from a time-dependent mean-field approach. Previous attempts to study fission dynamics using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that different…

Nuclear Theory · Physics 2015-05-18 A. S. Umar , V. E. Oberacker , J. A. Maruhn , P. -G. Reinhard

Density functional theory (DFT) can run into serious difficulties with localized states in elements such as transition metals with occupied-d states and oxygen. In contrast, Hartree-Fock (HF) method can be a better approach for such…

Materials Science · Physics 2018-08-01 Hengxin Tan , Yuanchang Li , S. B. Zhang , Wenhui Duan