An open‐source framework for analyzing <i>N</i>‐electron dynamics. II. Hybrid density functional theory/configuration interaction methodology

Hermann, Günter; Pohl, Vincent; Tremblay, Jean Christophe

doi:10.1002/jcc.24896

Cited by 50 publications

(59 citation statements)

References 63 publications

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“…These are connected via the electronic continuity equation, ∂ t ρ(r, t) = − ∇ · j(r, t). Both the one-electron density and the current flux density are computed from the time-dependent many-electron wavepacket, as described elsewhere [60,61].…”

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confidence: 99%

Probing Electronic Fluxes via Time-Resolved X-Ray Scattering

et al. 2020

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The current flux density is a vector field that can be used to describe theoretically how electrons flow in a system out-of-equilibrium. In this work, we unequivocally demonstrate that the signal obtained from time-resolved X-ray scattering does not only map the time-evolution of the electronic charge distribution, but also encodes information about the associated electronic current flux density. We show how the electronic current flux density qualitatively maps the distribution of electronic momenta and reveals the underlying mechanism of ultrafast charge migration processes, while also providing quantitative information about the timescales of electronic coherences.Time-resolved imaging (TRI) of dynamically evolving electronic charge distribution is essential for complete understanding of complex chemical and biological processes in nature. Moreover, TRI of valence electron charge distribution is paramount to understand different instances during chemical reactions such as conformational changes, charge migration, and bond formation and breakage [1][2][3][4]. Following the quantum mechanical version of continuity equation, the flow of electron charge distribution is accompanied by associated electronic fluxes [5]. The concept of quantum electronic fluxes offers a wealth of crucial informations and has played a decisive role for understanding the mechanism of chemical reactions [6][7][8]. However, the notion of electronic fluxes has been restricted to theoretical modelling [9-18] and there is no general way to probe them directly in experiment. In this work, we will demonstrate a real-space and real-time imaging of electronic fluxes associated with attosecond non-stationary charge migration using time-resolved X-ray scattering (TRXS). For this purpose, we will consider benzene molecule as a test system in which a pump pulse will induce an adiabatic charge migration and ultrashort X-ray pulses will probe the electronic fluxes accompanying charge migration.Scattering of X-rays from matter is an indispensable technique to unveil the real-space structure of solids, biomolecules and molecules with atomic-scale spatial resolution [19]. Tremendous technological progress has been made to generate tunable ultraintense and ultrashort Xray pulses from X-ray free-electron lasers (XFELs) [20][21][22]. X-ray pulses with few femtoseconds pulse duration are routinely generated at various XFELs (LCLS, SACLA, European XFEL). Moreover, few successful attempts have been demonstrated to generate attosecond X-ray pulses [23][24][25][26][27][28]. The availability of these ultrashort X-ray pulses offer to extend X-ray scattering from static to time domain with unprecedented temporal resolution [29,30]. Scattering of ultrashort X-ray pulses from the temporarily evolving electronic charge distribution promises to provide stroboscopic snap-shots of matter in action with atomic-scale spatial and temporal resolutions [31,32]. A direct approach to envision TRXS is a pump-probe experiment, where the pump pulse triggers the ultrafast dynamics ...

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Probing Electronic Fluxes via Time-Resolved X-Ray Scattering

et al. 2020

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“…(f) Five snapshots of the one-electron density during periodic charge migration of the superposition of the ground state labeled A 1g and the excited state labeled E 1u during one period, from t = t c = 0 to T. (g) One-electron density of the excited target state labeled E 1u . All densities were created using detCI@ORBKIT [43][44][45] and plotted using Matplotlib [46].…”

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confidence: 99%

“…The Gaussian shape functions (dashed lines) and the xand y-components of the electric field (red and green continuous lines) of the circularly-polarized laser pulses are also sketched. All densities were created using detCI@ORBKIT [43][44][45] and plotted using Matplotlib [46]. The xand y-components of the electric fields of the laser pulses are also sketched in Figure 1, together with the products b s b (t) and r s r (t) of the field amplitudes times the shape functions which are modeled as Gaussians,…”

Section: Conceptual Background For the New Symmetry Restoration Strategymentioning

confidence: 99%

From Symmetry Breaking via Charge Migration to Symmetry Restoration in Electronic Ground and Excited States: Quantum Control on the Attosecond Time Scale

2019

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This article starts with an introductory survey of previous work on breaking and restoring the electronic structure symmetry of atoms and molecules by means of two laser pulses. Accordingly, the first pulse breaks the symmetry of the system in its ground state with irreducible representation IRREP g by exciting it to a superposition of the ground state and an excited state with different IRREP e . The superposition state is non-stationary, representing charge migration with period T in the sub-to few femtosecond time domains. The second pulse stops charge migration and restores symmetry by de-exciting the superposition state back to the ground state. Here, we present a new strategy for symmetry restoration: The second laser pulse excites the superposition state to the excited state, which has the same symmetry as the ground state, but different IRREP e . The success depends on perfect time delay between the laser pulses, with precision of few attoseconds. The new strategy is demonstrated by quantum dynamics simulation for an oriented model system, benzene.

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“…[41][42][43][44][45] All atomic orbitals and their derivatives are projected on a grid using ORBKIT. [46][47][48] For the semi-infinite leads the computational cell is sampled using 20 Monkhorst-Pack K-points along the periodic direction.…”

Section: Computational Set-upmentioning

confidence: 99%

Local current analysis on defective zigzag graphene nanoribbons devices for biosensor material applications

2021

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In this contribution, we aim at investigating the mechanism of biosensing in graphene-based materials from first principles. Inspired by recent experiments, we construct an atomistic model composed of a pyrene molecule serving as a linker fragment, which is used in experiment to attach certain aptamers, and a defective zigzag graphene nanoribbons (ZGNRs). Density functional theory including dispersive interaction is employed to study the energetics of the linker absorption on the defective ZGNRs. Combining non-equilibrium Green's function and the Landauer formalism, the total current-bias voltage dependence through the device is evaluated. Modifying the distance between the linker molecule and the nanojunction plane reveals a quantitative change in the total current-bias voltage dependence, which correlates to the experimental measurements. In order to illuminate the geometric origin of these variation observed in the considered systems, the local currents through the device are investigated using the method originally introduced by Evers and co-workers. In our new implementation, the numerical efficiency is improved by applying sparse matrix storage and spectral filtering techniques, without compromising the resolution of the local currents. Local current density maps qualitatively demonstrate the local variation of the interference between the linker molecule and the nanojunction plane.

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An open‐source framework for analyzing N‐electron dynamics. II. Hybrid density functional theory/configuration interaction methodology

Cited by 50 publications

References 63 publications

Probing Electronic Fluxes via Time-Resolved X-Ray Scattering

Probing Electronic Fluxes via Time-Resolved X-Ray Scattering

From Symmetry Breaking via Charge Migration to Symmetry Restoration in Electronic Ground and Excited States: Quantum Control on the Attosecond Time Scale

Local current analysis on defective zigzag graphene nanoribbons devices for biosensor material applications

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