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We present a cost-effective treatment of the triple excitation amplitudes in the time-dependent optimized coupled-cluster (TD-OCC) framework called TD-OCCDT(4) for studying intense laser-driven multielectron dynamics. It considers triple…

Chemical Physics · Physics 2021-07-07 Himadri Pathak , Takeshi Sato , Kenichi L. Ishikawa

Time-dependent coupled-cluster method with time-varying orbital functions, called time-dependent optimized coupled- cluster (TD-OCC) method, is formulated for multielectron dynamics in an intense laser field. We have successfully derived…

Chemical Physics · Physics 2018-03-14 Takeshi Sato , Himadri Pathak , Yuki Orimo , Kenichi L. Ishikawa

We calculate the high-harmonic generation (HHG) spectra, strong-field ionization, and time-dependent dipole-moment of Ne using explicitly time-dependent optimized second-order many-body perturbation method (TD-OMP2) where both orbitals and…

Chemical Physics · Physics 2020-08-18 Himadri Pathak , Takeshi Sato , Kenichi L. Ishikawa

In parallel with the evolution of femtosecond and attosecond laser as well as free-electron laser technology, a variety of theoretical methods have been developed to describe the behavior of atoms, molecules, clusters, and solids under the…

Atomic Physics · Physics 2015-11-12 Kenichi L. Ishikawa , Takeshi Sato

We employ the time-dependent Hartree-Fock (TDHF) method to study various aspects of the reactions utilized in searches for superheavy elements. These include capture cross-sections, quasifission, prediction of $P_{\mathrm{CN}}$, and other…

Nuclear Theory · Physics 2016-04-12 A. S. Umar , V. E. Oberacker

This article concerns the time-dependent Hartree-Fock (TDHF) approximation of single-particle dynamics in systems of interacting fermions. We find that the TDHF approximation is accurate when there are sufficiently many particles and the…

Quantum Physics · Physics 2015-02-25 Claude Bardos , Francois Golse , Alex D. Gottlieb , Norbert J. Mauser

We demonstrate that the microscopic Time-dependent Hartree-Fock (TDHF) theory provides an important approach to shed light on the nuclear dynamics leading to the formation of superheavy elements. In particular, we discuss studying…

Nuclear Theory · Physics 2017-12-06 A. S. Umar , C. Simenel , S. Ayik

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

The density-constrained time-dependent Hartree-Fock (DC-TDHF) theory is a fully microscopic approach for calculating heavy-ion interaction potentials and fusion cross sections below and above the fusion barrier. We discuss recent…

Nuclear Theory · Physics 2014-02-07 A. S. Umar , V. E. Oberacker , R. Keser , J. A. Maruh , P. -G. Reinhard

We report a three-dimensional numerical implementation of multiconfiguration time-dependent Hartree-Fock (MCTDHF) based on a multi-resolution Cartesian grid, with no need to assume any symmetry of molecular structure. We successfully…

Computational Physics · Physics 2016-03-23 Ryohto Sawada , Takeshi Sato , Kenichi L. Ishikawa

We report the formulation of a new, cost-effective approximation method in the time-dependent optimized coupled-cluster (TD-OCC) framework [T. Sato et al., J. Chem. Phys. 148, 051101 (2018)] for first-principles simulations of multielectron…

Chemical Physics · Physics 2022-08-11 Himadri Pathak , Takeshi Sato , Kenichi L. Ishikawa

Time-dependent quantum chemical methods coupled to Gaussian basis sets are gaining popularity in modeling the electron dynamics of atoms and molecules interacting with intense laser fields. Two approaches most widely used for this purpose,…

Chemical Physics · Physics 2023-01-18 Aleksander P. Woźniak , Maciej Lewenstein , Robert Moszyński

Time-dependent Hartree-Fock (TDHF) is one of the fundamental post-Hartree-Fock (HF) methods to describe excited states. In its Tamm-Dancoff form, equivalent to Configuration Interaction Singles, it is still widely used and particularly…

Chemical Physics · Physics 2024-11-18 Uday Panta , David A. Strubbe

In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach,…

Nuclear Theory · Physics 2015-02-16 V. E. Oberacker , A. S. Umar

A challenge in modeling time-dependent strong-field processes such as high-harmonic generation for many-body systems, is how to effectively represent the electronic continuum. We apply Rothe's method to the time-dependent Hartree-Fock…

Chemical Physics · Physics 2025-08-22 Simon Elias Schrader , Håkon Emil Kristiansen , Thomas Bondo Pedersen , Simen Kvaal

We introduce an individually fitted screened-exchange interaction for the time-dependent Hartree-Fock (TDHF) method and show that it resolves the missing binding energies in polymethine organic dye molecules compared to time-dependent…

Chemical Physics · Physics 2024-06-21 Nadine C. Bradbury , Barry Y. Li , Tucker Allen , Justin R. Caram , Daniel Neuhauser

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

We investigate the multielectron effects on high-harmonic generation from solid-state materials using the time-dependent Hartree-Fock theory. We find qualitative change in harmonic spectra, in particular, multiple-plateau formation at…

We apply a three-dimensional (3D) implementation of the time-dependent restricted-active-space self-consistent-field (TD-RASSCF) method to investigate effects of electron correlation in the ground state of Be as well as in its…

Atomic Physics · Physics 2017-06-07 Juan J. Omiste , Wenliang Li , Lars Bojer Madsen

This work establishes the time-dependent relativistic Hartree-Fock (TD-RHF) model with spherical symmetry for the first time. The time-dependent integro-differential Dirac equations are solved by expanding Dirac spinors on the spherical…

Nuclear Theory · Physics 2024-06-13 Jing Geng , Zhi Heng Wang , Peng Wei Zhao , Yi Fei Niu , Haozhao Liang , Wen Hui Long