A single-electron picture based on the multiconfiguration time-dependent Hartree–Fock method: application to the anisotropic ionization and subsequent high-harmonic generation of the CO molecule

Ohmura, Shu; Katō, Takako; Oyamada, Takayuki; Koseki, Shiro; Ohmura, Hideki; Kono, Hirohiko

doi:10.1088/1361-6455/aa9e45

Cited by 24 publications

(48 citation statements)

References 86 publications

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“…The experimental angular distribution shows narrower widths with peak angles slightly shifted towards the polarization axis. These deviations could be attributed to the multi-orbital effects, 48,57 the electron rescattering involved in the dissociation process, 41 and possibly to the laser induced molecular alignment.…”

Section: Laser Tunneling Ionizationmentioning

confidence: 99%

“…Intensive studies have been carried out to clarify the underlying physics, which led to developments of ultrafast spectroscopy, establishing real-time probing and imaging of molecular dynamics with a high time resolution. 57 Intense laser fields also provide a unique approach to control chemical reactions by manipulation of molecular potential energy surfaces (PESs) by light-dressing. 8 In the present Account, we intend to illustrate how one can utilize ultrashort intense laser fields in chemistry by referring to previous studies carried out in our laboratory.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast Reaction Imaging and Control by Ultrashort Intense Laser Pulses

Hishikawa

Matsuda

Fushitani

2020

Bulletin of the Chemical Society of Japan

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Molecules irradiated with intense laser pulses (field intensity ³10 15 W/cm 2) exhibit a variety of characteristic processes, such as tunneling ionization, electron rescattering, high-order harmonics generation and Coulomb explosion, that cannot be seen in a weak light field. These features have attracted attention in the last decades as they provide unique approaches to visualize and manipulate ultrafast dynamics of atoms and molecules. Here we discuss molecular processes in intense laser fields, with focuses on the applications to ultrafast imaging and control of reaction dynamics.

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Section: Laser Tunneling Ionizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultrafast Reaction Imaging and Control by Ultrashort Intense Laser Pulses

Hishikawa

Matsuda

Fushitani

2020

Bulletin of the Chemical Society of Japan

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“…In our previous papers [86][87][88][89][90], a novel approach, i.e., a single orbital picture was established under the framework of the MCTDHF. We adopted the representation of TD natural spinorbitals (SOs) {ϕ j (t)} (see, for the natural SO, [91]), which diagonalizes the first-order reduced density matrix of electrons constructed from the MCTDHF multielectron wave function Ψ(t).…”

Section: Introductionmentioning

confidence: 99%

“…We adopted the representation of TD natural spinorbitals (SOs) {ϕ j (t)} (see, for the natural SO, [91]), which diagonalizes the first-order reduced density matrix of electrons constructed from the MCTDHF multielectron wave function Ψ(t). The orbital-dependent effective potentials {υ eff j (t)} that govern the time evolution of {ϕ j (t)} under the influence of electron correlation were then derived as a function of the spatial coordinate of an electron, r [88][89][90]. The obtained effective potential υ eff j (r, t) for ϕ j (t) can be partitioned into υ eff j (t) υ 1 (t) + υ 2,j (t), where υ 1 (t) is the one-body interaction and υ 2,j (t) originates from the two-body interaction between electrons.…”

Section: Introductionmentioning

confidence: 99%

“…The obtained effective potential υ eff j (r, t) for ϕ j (t) can be partitioned into υ eff j (t) υ 1 (t) + υ 2,j (t), where υ 1 (t) is the one-body interaction and υ 2,j (t) originates from the two-body interaction between electrons. We have investigated the mechanisms of the directional anisotropy in intense-field induced ionization of heteronuclear diatomic molecules CO [88][89][90] and LiH [90] by scrutinizing the temporal change in their effective potentials. The results of CO effective potentials are summarized in the second last paragraph of this section.…”

Section: Introductionmentioning

confidence: 99%

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Manipulation of Multielectron Dynamics of Molecules by Fourier-Synthesized Intense Laser Pulses: Effective Potential Analysis of CO

Ohmura

Katō

et al. 2021

Front. Phys.

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We present a theoretical investigation as to how multielectron dynamics of CO are manipulated by Fourier-synthesized intense laser pulses. The pulses used are assumed to be comprised of harmonics up to the fourth order. The multiconfiguration time-dependent (TD) Hartree-Fock (MCTDHF) method, where the multielectron wavefunction Ψ(t) is expressed as a linear combination of various electron configurations, is employed to simulate the dynamics of CO interacting with Fourier-synthesized pulses. The multielectron nature such as electron correlation is quantified by using our effective potential approach. To begin with, the time-dependent natural orbitals {ϕj(r,t)} which diagonalize the first order reduced density matrix are obtained from Ψ(t), where r is the one-electron coordinate. The effective potentials υjeff(r,t) that determine the dynamics of ϕj(r,t) are then derived from the equations of motion for {ϕj(r,t)}. υjeff(r,t) consists of the one-body part υ1(t) including the interaction with the laser electric field ε(t) and the two-body part υ2,j(t) originating from electron-electron interaction. In this way, the role of electron correlation can be quantified by comparing υjeff(r,t) with those obtained by the TDHF method, where Ψ(t) is approximated by a single Slater determinant. We found a very similar profile in υ5σeff(r,t) of the 5σ highest occupied molecular orbital for both near-infrared one-color (ω) and directionally asymmetric ω+2ω two-color pulses; when ε(t) points from the nucleus C to O, a hump appears in υ5σeff(r,t) only 2 bohrs outward from C. The hump formation, which originates from the field-induced change in υ2,5σ(t) (especially, due to electron correlation), is responsible for preferential electron ejection from the C atom side (experimentally observed anisotropic ionization). A coherent superposition of ω and 2ω fields with an appropriate relative phase thus works as a one-color pulse of which either positive or negative peaks are filtered out. More sophisticated manipulation is possible by adding higher harmonics to a synthesized field. We show that the 5σ orbital can be squeezed toward the inside of the potential valley in υ5σeff(r,t), which encloses the molecule at a radius of ∼7 bohrs (semicircle in the region of z <0), by adjusting the phases of a ω+2ω+3ω+4ω field. The hump and valley formation in υ5σeff(r,t) are closely correlated with domains of increasing and decreasing electron density, respectively.

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