Time-dependent geminal method applied to laser-driven beryllium

Lötstedt, Erik; Katō, Takako; Yamanouchi, Kaoru

doi:10.1103/physreva.97.013423

Cited by 5 publications

(8 citation statements)

References 99 publications

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“…We solve the MCTDHF equations of motion in the same way as described in [51,55]. The details of the numerical implementation of the MCTDHF method are summarized in Appendix A.…”

Section: B Mctdhfmentioning

confidence: 99%

“…VAJVA-19-04). M. F. C. acknowledges the project Advanced research using high intensity laser produced photons and particles (CZ.02.1.01/0.0/0.0/ 16 019/0000789) from European Regional Development Fund The numerical method used for the solution of the MCTDHF equations of motion is the same as that presented in [51,55]. We describe the essential points below.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…The time evolution is calculated by a predictor-corrector method similar to that presented in [65], with a time step of δt ′ = 5 × 10 −3 a.u. Further details can be found in Appendix E of [55]. The equations for perturbation theory up to order three in 1/Z are given as…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Static-field ionization model of He-like ions for diagnostics of light-field intensity

2020

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We study static-field ionization of He-like ions with nuclear charge number in the range of 2 ≤ Z ≤ 36. Both the tunneling and over-the-barrier regimes are considered. We calculate the ionization rates by three approximate methods: a fitting formula based on the Perelemov-Popov-Terent'ev (PPT) formula, a perturbative expansion in powers of 1/Z, and a single-active electron approximation, and compare them with reference ionization rates computed by the multiconfiguration time-dependent Hartree-Fock (MCTDHF) approach. The relative deviation of the rates computed by the PPT-based fitting formula and the third-order perturbation theory from the rates computed by the MCTDHF approach is found to be around 10%. We discuss quantitatively the contribution from the exchange interaction during the ionization by comparing the single-active electron rates and the reference rates in which multielectron effects are included. We find that a single-active electron approximation, where the exchange interaction is neglected, results in the overestimation of the ionization rates by 30% for He and 2% for He-like Kr, showing that the magnitude of the effect of the exchange interaction scales approximately as 1/Z.

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“…We solve the MCTDHF equations of motion in the same way as described in [51,55]. The details of the numerical implementation of the MCTDHF method are summarized in Appendix A.…”

Section: B Mctdhfmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

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Static-field ionization model of He-like ions for diagnostics of light-field intensity

2020

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“…( 19)] contributing to the mean-field [Eq. ( 18)], for which we use a Poisson solver thereby achieving linear scaling with the number of basis functions (or equivalently, grid points) [35,46,[49][50][51]. A split-operator propagator is developed with an efficient implicit method for stiff derivative operators which drastically stabilizes the temporal propagation of orbitals.…”

Section: Numerical Implementation For Atomsmentioning

confidence: 99%

Time-Dependent Complete-Active-Space Self-Consistent-Field Method for Ultrafast Intense Laser Science

Sato

Orimo

Teramura

et al. 2018

Springer Series in Chemical Physics

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We present the time-dependent complete-active-space self-consistent-field (TD-CASSCF) method to simulate multielectron dynamics in ultrafast intense laser fields from the first principles. While based on multiconfiguration expansion, it divides the orbital space into frozen-core (tightly bound electrons with no response to the field), dynamical-core (electrons tightly bound but responding to the field), and active (fully correlated to describe highly excited and ejected electrons) orbital subspaces. The subspace decomposition can be done flexibly, conforming to phenomena under investigation and desired accuracy. The method is gauge invariant and size extensive. Infinite-range exterior complex scaling in addition to maskfunction boundary is adopted as an efficient absorbing boundary. We show numerical examples and illustrate how to extract relevant physical quantities such as ion-

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“…However, these methods scale factorially with the number of correlated electrons, re-stricting large scale applications. By limiting the configuration interaction (CI) expansion of the wavefunction up to an affordable level, various less demanding methods [29][30][31][32][33] like the time-dependent restricted-activespace self-consistent field (TD-RASSCF) 29,30 and timedependent occupation-restricted multiple-active-space (TD-ORMAS) 32 have been developed. These methods have proven to be of great utility 34 even though not sizeextensive.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent optimized coupled-cluster method for multielectron dynamics IV: Approximate consideration of the triple excitation amplitudes

Pathak,

Sato,

Ishikawa

2021

Preprint

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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 excitation amplitudes correct up to fourth-order in many-body perturbation theory and achieves a computational scaling of O(N 7 ), with N being the number of active orbital functions. This method is applied to the electron dynamics in Ne and Ar atoms exposed to an intense near-infrared laser pulse with various intensities. We benchmark our results against the time-dependent complete-activespace self-consistent field (TD-CASSCF), time-dependent optimized coupled-cluster with double and triple excitations (TD-OCCDT), time-dependent optimized coupled-cluster with double excitations (TD-OCCD), and the time-dependent Hartree-Fock (TDHF) methods to understand how this approximate scheme performs in describing nonperturbatively nonlinear phenomena, such as field-induced ionization and high-harmonic generation. We find that the TD-OCCDT(4) method performs equally well as the TD-OCCDT method, almost perfectly reproducing the results of fully-correlated TD-CASSCF with a more favorable computational scaling.

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Time-dependent geminal method applied to laser-driven beryllium

Cited by 5 publications

References 99 publications

Static-field ionization model of He-like ions for diagnostics of light-field intensity

Static-field ionization model of He-like ions for diagnostics of light-field intensity

Time-Dependent Complete-Active-Space Self-Consistent-Field Method for Ultrafast Intense Laser Science

Time-dependent optimized coupled-cluster method for multielectron dynamics IV: Approximate consideration of the triple excitation amplitudes

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