Attosecond photoionization dynamics in neon

Omiste, Juan J.; Madsen, Lars Bojer

doi:10.1103/physreva.97.013422

Cited by 19 publications

(41 citation statements)

References 57 publications

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“…(i) From the computed wavefunction, one extracts the expectation value of the radial distance in a given direction, r(t) , as a function of time and the linear momentum of the photoelectron, k that can be evaluated in different ways. For instance k , can be evaluated via integrating only in the outer part of the simulation volume (Omiste et al, 2017;Omiste and Madsen, 2018). (ii) Using r(t) and k the effective ionization time,…”

Section: A Extraction Of Observablesmentioning

confidence: 99%

Colloquium : Multiconfigurational time-dependent Hartree approaches for indistinguishable particles

et al. 2020

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In this Colloquium, the wavefunction-based Multiconfigurational Time-Dependent Hartree approaches to the dynamics of indistinguishable particles (MCTDH-F for Fermions and MCTDH-B for Bosons) are reviewed. MCTDH-B and MCTDH-F or, together, MCTDH-X are methods for describing correlated quantum systems of identical particles by solving the time-dependent Schrödinger equation from first principles. MCTDH-X is used to accurately model the dynamics of real-world quantum many-body systems in atomic, molecular, and optical physics. The key feature of these approaches is the time-dependence and optimization of the single-particle states employed for the construction of a many-body basis set, which yields nonlinear working equations. We briefly describe the historical developments that have lead to the formulation of the MCTDH-X methods and motivate the necessity for wavefunction-based approaches. We sketch the derivation of the unified MCTDH-F and MCTDH-B equations of motion for complete and also specific restricted configuration spaces. The strengths and limitations of the MCTDH-X approach are assessed via benchmarks against an exactly solvable model and via convergence checks. We highlight some applications to instructive and experimentally-realized quantum many-body systems: the dynamics of atoms in Bose-Einstein condensates in magneto-optical and optical traps and of electrons in atoms and molecules. We discuss the current development and frontiers in the field of MCTDH-X: theories and numerical methods for indistinguishable particles, for mixtures of multiple species of indistinguishable particles, the inclusion of nuclear motion for the nonadiabatic dynamics of atomic and molecular systems, the so-called multilayer generalizations to the MCTDH-F and MCTDH-B methods, and the time-dependent orbital-adaptive coupled cluster theory are discussed.

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Section: A Extraction Of Observablesmentioning

confidence: 99%

Colloquium : Multiconfigurational time-dependent Hartree approaches for indistinguishable particles

et al. 2020

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“…In this work, we take the initial orbitals to be hydrogenic with nuclear charge Z and ordered as 1s, 2s, 2p, 3s, 3p and 3d. This selection is adequate since the magnetic quantum number of each orbital is preserved in the MCTDHF, TD-CASSCF and TD-RASSCF methods 35,41 . See Appendix A for further details.…”

Section: Resultsmentioning

confidence: 99%

“…The TD-RASSCF method is used to propagate the many-electron wave function. The method was described in detail elsewhere 33,37,38,[40][41][42] , so the description here will be brief.…”

Section: A Td-rasscf Methodsmentioning

confidence: 99%

“…In these methods the number of orbitals can be reduced by introducing time-dependent orbitals, which therefore implies a smaller number of configurations. The most commonly used SCF methods which include correlation are multiconfigurational time-dependent Hartree-Fock (MCTDHF) 14,[20][21][22][23][24][25][26][27][28][29][30][31] , time-dependent completeactive-space SCF (TD-CASSCF) [32][33][34][35][36] and time-dependent restricted-active-space SCF (TD-RASSCF) 33,[37][38][39][40][41][42] approaches. Specifically, TD-RASSCF not only reduces the number of orbitals, but also the number of configurations can be reduced by appropriately choosing the restricted-active-space (RAS).…”

Section: Introductionmentioning

confidence: 99%

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Effects of core space and excitation levels on ground-state correlation and photoionization dynamics of Be and Ne

Omiste

Madsen

2019

The Journal of Chemical Physics

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We explore the effects of correlation on the ground-state energies and on photoionization dynamics in atomic Be and Ne. We apply the time-dependent restricted-activespace self-consistent-field method for several excitation schemes and active orbital spaces with and without a dynamic core to address the effects systematically at different levels of approximation. For the ground-state many-electron wave functions, we compare the correlation energies with entropic measures of entanglement. A larger magnitude of the correlation energy does not always correspond to a larger value of the considered entanglement measures. To evaluate the impact of correlation in a process involving continua, we consider photoionization by attosecond pulses. The photoelecton spectra may be significantly affected by including a dynamical core.

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“…Over the past years, various timedependent many-electron methods have been developed to address dynamic electron correlation in strong-field ionization of atoms and molecules. Among those, the timedependent R-matrix approach [35][36][37][38], the time-dependent Feshbach close-coupling (TDFCC) method [39], the multiconfigurational time-dependent Hartree-Fock (MCTDHF) method [40][41][42][43][44][45], and the time-dependent restricted-activespace self-consistent-field (TD-RAS-SCF) theory [46][47][48][49][50][51][52][53] have been used to understand dynamics. The time-dependent restricted-active-space configuration-interaction (TD-RASCI) method [54], and the time-dependent generalized-activespace configuration-interaction (TD-GASCI) method [33,34,55] take electron correlation into account through a configuration-interaction (CI) expansion by selectively choosing important Slater determinants relevant to the physical process of interest.…”

Section: Introductionmentioning

confidence: 99%

Electron correlation effects in enhanced ionization of diatomic molecules in near-infrared fields

Chattopadhyay

Madsen

2019

Phys. Rev. A

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We investigate electron correlation effects in internuclear-distance-dependent enhanced ionization of H2, LiH, and HF molecules by intense near-infrared laser pulses using a 3D description of the systems with the timedependent generalized-active-space configuration-interaction method. This method systematically incorporates electron-electron correlation of the quantum many-electron system under consideration. Our correlated description of diatomic molecules shows that enhanced ionization occurs at certain critical internuclear separations and electron correlation systematically improves the ionization probability in this process until convergence is reached. We demonstrate the failure of the single-active-electron and the configuration-interaction singles approximations to produce the correct internuclear position and probability of the strong-field enhanced-ionization process. We elucidate the role of low-lying electronic excited states in the enhanced ionization process of diatomic molecules. There is clear evidence that an accurate description of low-lying electronically excited states is important to describe the non-perturbative enhanced ionization phenomenon in the ultrashort intense near infrared laser pulses. arXiv:1812.05317v1 [physics.atom-ph]

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Attosecond photoionization dynamics in neon

Cited by 19 publications

References 57 publications

Colloquium : Multiconfigurational time-dependent Hartree approaches for indistinguishable particles

Colloquium : Multiconfigurational time-dependent Hartree approaches for indistinguishable particles

Effects of core space and excitation levels on ground-state correlation and photoionization dynamics of Be and Ne

Electron correlation effects in enhanced ionization of diatomic molecules in near-infrared fields

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