Hybrid approach to molecular continuum processes combining Gaussian basis functions and the discrete variable representation

Rescigno, T. N.; Horner, D. A.; Yip, Frank L.; McCurdy, C. William

doi:10.1103/physreva.72.052709

Cited by 36 publications

(29 citation statements)

References 31 publications

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“…3 for four different orientations of the molecule with respect to the direction of polarization. These results are also in good agreement with other recent accurate calculations [25,26].…”

Section: B Continuum States Of H +supporting

confidence: 93%

Grid-based methods for diatomic quantum scattering problems: A finite-element discrete-variable representation in prolate spheroidal coordinates

2009

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We show how to combine finite elements and the discrete variable representation in prolate spheroidal coordinates to develop a grid-based approach for quantum mechanical studies involving diatomic molecular targets. Prolate spheroidal coordinates are a natural choice for diatomic systems and have been used previously in a variety of bound-state applications. The use of exterior complex scaling in the present implementation allows for a transparently simple way of enforcing Coulomb boundary conditions and therefore straightforward application to electronic continuum problems. Illustrative examples involving the bound and continuum states of H + 2 , as well as the calculation of photoionization cross sections, show that the speed and accuracy of the present approach offer distinct advantages over methods based on single-center expansions.

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“…3 for four different orientations of the molecule with respect to the direction of polarization. These results are also in good agreement with other recent accurate calculations [25,26].…”

Section: B Continuum States Of H +supporting

confidence: 93%

Grid-based methods for diatomic quantum scattering problems: A finite-element discrete-variable representation in prolate spheroidal coordinates

2009

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“…[14], the DCSs predicted in Refs. [16,17], and our present numbers, are not directly comparable. Although by no means obvious, the present investigations revealed that apparently different definitions were used for the angle-resolved differential cross sections.…”

Section: B One-photon Ionizationcontrasting

confidence: 91%

“…(40 eV). Very good agreement was achieved between results from time-dependent closecoupling (TDCC) treatments [14,15] in spherical coordinates and time-independent exterior complex scaling (ECS) calculations [16,17] for the parallel geometry of θ N = 0…”

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confidence: 64%

Multiphoton ionization of H2+in xuv laser pulses

et al. 2011

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We consider the ionization of the hydrogen molecular ion after one-, two-, and three-photon absorption over a large range of photon energies between 9 and 40 eV in the fixed-nuclei approximation. The temporal development of the system is obtained in a fully ab initio time-dependent grid-based approach in prolate spheroidal coordinates. The alignment dependence of the one-photon ionization amplitude is highlighted in the framework of time-dependent perturbation theory. For one-photon ionization as a function of the nuclear separation, the calculations reveal a significant minimum in the ionization probability. The suppressed ionization is attributed to a Cooper-type minimum, which is similar, but not identical, to the cancellation effect observed in photoionization cross sections of some noble-gas atoms. The effect of the nonspherical two-center Coulomb potential is analyzed. For two-and three-photon ionization, the angle-integrated cross sections clearly map out intermediate-state resonance, and the predictions of the current computations agree very well with those from time-independent calculations. The dominant emission modes for two-photon ionization are found to be very similar in both resonance and off-resonance regions.

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“…Thus most solutions proposed in the literature have adopted a more pragmatical approach, which is to combine existing QCPs with scattering methods that incorporate the latter basis functions. For instance, recently proposed methods complement the short-range part represented by Gaussian functions with a finite element (FE) representation of the radial coordinate [40,41], or a discrete variable representation (DVR) [42][43][44][45][46], or even plane waves [47]. Others just get rid of all exponentially decreasing functions by fitting them to a multicenter B-spline expansion and adding additional B-splines for the continuum part [48].…”

Section: Introductionmentioning

confidence: 99%

Photoionization using the xchem approach: Total and partial cross sections of Ne and resonance parameters above the 2s22p5 threshold

et al. 2017

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The XCHEM approach interfaces well established quantum chemistry packages with scattering numerical methods in order to describe single-ionization processes in atoms and molecules. This should allow one to describe electron correlation in the continuum at the same level of accuracy as quantum chemistry methods do for bound states. Here we have applied this method to study multichannel photoionization of Ne in the vicinity of the autoionizing states lying between the 2s 2 2p 5 and 2s2p 6 ionization thresholds. The calculated total photoionization cross sections are in very good agreement with the absolute measurement of Samson et al.[J. Electron Spectrosc. Relat. Phenom. 123, 265 (2002)], and with independent benchmark calculations performed at the same level of theory. From these cross sections, we have extracted resonance positions, total autoionization widths, Fano profile parameters, and correlation parameters for the lowest three autoionizing states. The values of these parameters are in good agreement with those reported in earlier theoretical and experimental work. We have also evaluated β asymmetry parameter and partial photoionization cross sections and, from the latter, partial autoionization widths and Starace parameters for the same resonances, not yet available in the literature. Resonant features in the calculated β parameter are in good agreement with the experimental observations. We have found that the three lowest resonances preferentially decay into the 2p −1 d continuum rather than into the 2p −1 s one [Phys. Rev. A 89, 043415 (2014)], in agreement with previous expectations, and that in the vicinity of the resonances the partial 2p −1 s cross section can be larger than the 2p −1 d one, in contrast with the accepted idea that the latter should amply dominate in the whole energy range. These results show the potential of the XCHEM approach to describe highly correlated process in the ionization continuum of many-electron systems, in particular molecules, for which the XCHEM code has been specifically designed.

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Hybrid approach to molecular continuum processes combining Gaussian basis functions and the discrete variable representation

Cited by 36 publications

References 31 publications

Grid-based methods for diatomic quantum scattering problems: A finite-element discrete-variable representation in prolate spheroidal coordinates

Grid-based methods for diatomic quantum scattering problems: A finite-element discrete-variable representation in prolate spheroidal coordinates

Multiphoton ionization of H2+in xuv laser pulses

Photoionization using the xchem approach: Total and partial cross sections of Ne and resonance parameters above the 2s22p5 threshold

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