Perturbative and nonperturbative photoionization of 
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 using the molecular 
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Benda, Jakub; Gorfinkiel, Jimena D.; Mašín, Zdeněk; Armstrong, Gregory; Brown, A. C.; Clarke, Daniel D. A.; Hart, H. W. van der; Wragg, Jack

doi:10.1103/physreva.102.052826

Cited by 30 publications

(37 citation statements)

References 76 publications

(161 reference statements)

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“…The RABITT experiment can be directly simulated using a solution of the time-dependent Schrödinger equation in the molecular frame. To provide such benchmark results, we used the molecular RMT [36]. In all timedependent calculations performed as part of this work we used the same combination of an attosecond XUV pulse train (APT, consisting of odd harmonics of the IR field frequency) and a probe IR pulse as given in [14].…”

Section: B Reference Rabitt Delays From Time-dependent Calculationsmentioning

confidence: 99%

Analysis of RABITT time delays using the stationary multi-photon molecular R-matrix approach

Benda,

Mašín,

Gorfinkiel

2022

Preprint

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We employ the recently developed multi-photon R-matrix method for molecular above-threshold photoionization to obtain second-order ionization amplitudes that govern the interference in RA-BITT experiments. This allows us to extract RABITT time delays that are in better agreement with non-perturbative time-dependent simulations of this process than the typically used combination of first-order (Wigner) delays and asymptotic corrections. We calculate molecular-frame as well as orientation-averaged RABITT delays for H2, N2, CO2, H2O and N2O and analyze the origin of various structures in the time delays including the effects of partial wave interference, shape resonances and orientation-averaging. Time-delays for B and C states of CO + 2 are strongly affected by absorption of the second (IR) photon in the ion. This effect corresponds to an additional contribution, τ coupl , to the asymptotic approximation for the RABITT delays τ ≈ τ mol + τcc + τ coupl . Applicability of the asymptotic theory depends on the target and IR photon energy but typically starts at approximately 30 -35 eV of XUV photon energy.

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Section: B Reference Rabitt Delays From Time-dependent Calculationsmentioning

confidence: 99%

Analysis of RABITT time delays using the stationary multi-photon molecular R-matrix approach

Benda,

Mašín,

Gorfinkiel

2022

Preprint

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“…Recent work on basis sets includes the development of B-spline functions, both on their own [32][33][34][35][36][37][38][39][40]48], and in hybrid combinations with Gaussian-type orbitals (GTOs) [45][46][47], as well as finite-difference approaches [49][50][51], finite-element discrete-variablerepresentation functions [52,53], grid-based methods [54,55], and simple plane-waves [56].…”

Section: Ab Initio and Numerical Methodsmentioning

confidence: 99%

Dialogue on analytical and ab initio methods in attoscience

et al. 2021

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The perceived dichotomy between analytical and ab initio approaches to theory in attosecond science is often seen as a source of tension and misconceptions. This Topical Review compiles the discussions held during a round-table panel at the ‘Quantum Battles in Attoscience’ cecam virtual workshop, to explore the sources of tension and attempt to dispel them. We survey the main theoretical tools of attoscience—covering both analytical and numerical methods—and we examine common misconceptions, including the relationship between ab initio approaches and the broader numerical methods, as well as the role of numerical methods in ‘analytical’ techniques. We also evaluate the relative advantages and disadvantages of analytical as well as numerical and ab initio methods, together with their role in scientific discovery, told through the case studies of two representative attosecond processes: non-sequential double ionisation and resonant high-harmonic generation. We present the discussion in the form of a dialogue between two hypothetical theoreticians, a numericist and an analytician, who introduce and challenge the broader opinions expressed in the attoscience community.

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“…Combining this with an outer region treated by the finitedifference techniques used in the HELIUM code [33] led to the first incarnation of the R-matrix with time dependence (RMT) method [34] in 2011. Since then the code has undergone extensive development, with extensions to treat arbitrary light fields [35], molecular targets [36], and the spin-orbit interaction using input from the RMATRX-I suite of codes [37], as well as improvements to the parallelization scheme [38]. It is still under active development by researchers located mostly in the UK.…”

Section: Introductionmentioning

confidence: 99%

Generalizations of the R-Matrix Method to the Treatment of the Interaction of Short-Pulse Electromagnetic Radiation with Atoms

Schneider

Hamilton

Bartschat

2022

Atoms

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Since its initial development in the 1970s by Phil Burke and his collaborators, the R-matrix theory and associated computer codes have become the method of choice for the calculation of accurate data for general electron–atom/ion/molecule collision and photoionization processes. The use of a non-orthogonal set of orbitals based on B-splines, now called the B-spline R-matrix (BSR) approach, was pioneered by Zatsarinny. It has considerably extended the flexibility of the approach and improved particularly the treatment of complex many-electron atomic and ionic targets, for which accurate data are needed in many modelling applications for processes involving low-temperature plasmas. Both the original R-matrix approach and the BSR method have been extended to the interaction of short, intense electromagnetic (EM) radiation with atoms and molecules. Here, we provide an overview of the theoretical tools that were required to facilitate the extension of the theory to the time domain. As an example of a practical application, we show results for two-photon ionization of argon by intense short-pulse extreme ultraviolet radiation.

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Perturbative and nonperturbative photoionization of H2 and H2O using the molecular R<

Cited by 30 publications

References 76 publications

Analysis of RABITT time delays using the stationary multi-photon molecular R-matrix approach

Analysis of RABITT time delays using the stationary multi-photon molecular R-matrix approach

Dialogue on analytical and ab initio methods in attoscience

Generalizations of the R-Matrix Method to the Treatment of the Interaction of Short-Pulse Electromagnetic Radiation with Atoms

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