Imaging diffraction oscillations for inelastic collisions of NO radicals with He and D2

Jongh, Tim de; Karman, Tijs; Vogels, Sjoerd N.; Besemer, Matthieu; Suits, Arthur G.; Thompson, Jason; Groenenboom, Gerrit C.; Avoird, Ad van der; Meerakker, Sebastiaan Y. T. van de

doi:10.1063/1.4981023

Cited by 20 publications

(35 citation statements)

References 29 publications

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“…23 ). Both sets were computed at the CCSD(T) level and predict a resonance near 14 cm −1 , but one of the potentials 24 -which we will denote the complete basis set (CBS) potential-was based on a CBS extrapolation, while the other potential 25 -which we denote the F12 potential-used the explicitly correlated F12a method with a scaled contribution from triple excitations (Supplementary section 'Potential energy surfaces'). It turns out that the F12 potential is deeper than the CBS potential by nearly 2 cm −1 , which causes a 0.7 cm −1 shift of the predicted scattering resonances.…”

Section: Nature Chemistrymentioning

confidence: 99%

Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard

et al. 2018

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Over the last 25 years, the formalism known as coupled-cluster (CC) theory has emerged as the method of choice for the ab initio calculation of intermolecular interaction potentials. The implementation known as CCSD(T) is often referred to as the gold standard in quantum chemistry. It gives excellent agreement with experimental observations for a variety of energy-transfer processes in molecular collisions, and it is used to calibrate density functional theory. Here, we present measurements of low-energy collisions between NO radicals and H molecules with a resolution that challenges the most sophisticated quantum chemistry calculations at the CCSD(T) level. Using hitherto-unexplored anti-seeding techniques to reduce the collision energy in a crossed-beam inelastic-scattering experiment, a resonance structure near 14 cm is clearly resolved in the state-to-state integral cross-section, and a unique resonance fingerprint is observed in the corresponding differential cross-section. This resonance structure discriminates between two NO-H potentials calculated at the CCSD(T) level and pushes the required accuracy beyond the gold standard.

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Section: Nature Chemistrymentioning

confidence: 99%

Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard

et al. 2018

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“…Additional computational details and routines for evaluation of the potential can be found in Ref. 17.…”

Section: Numerical Results For No-hmentioning

confidence: 99%

“…A detailed discussion of the time-independent scattering calculations can be found in Ref. 17. Figure 7 shows integral cross sections for transitions to the NO j NO = 1/2 and 3/2 states as a function of the collision energy.…”

Section: Asymptotic Diabatizationmentioning

confidence: 99%

“…6,7 For molecule-molecule systems, such symmetry is generally absent, but progress has been made in method development [8][9][10][11][12][13][14] that now enables the treatment of these systems. [15][16][17][18][19] In particular, some of the present authors have developed a multiple-property-based diabatization scheme specifically tailored towards weakly interacting open-shell molecules. 20 Strong nonadiabatic coupling is also encountered for complexes involving open-shell atoms [21][22][23][24][25][26][27][28] as well as for non-linear molecules such as the methane and benzene cations, [29][30][31] which also have spatially degenerate electronic states.…”

Section: Introductionmentioning

confidence: 99%

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Diabatic states, nonadiabatic coupling, and the counterpoise procedure for weakly interacting open-shell molecules

Karman¹,

Besemer²,

Avoird³

et al. 2018

The Journal of Chemical Physics

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We study nonadiabatic coupling in systems of weakly interacting open-shell molecules which have nearly degenerate electronic states and hence significant nuclear derivative couplings. By comparison to numerically calculated nuclear derivatives of adiabatic electronic wave functions, we show that nonadiabatic couplings are represented accurately by diabatization using a recent multiple-propertybased algorithm [T. Karman et al., J. Chem. Phys. 144, 121101 (2016)]. Accurate treatment of weakly interacting molecules furthermore requires counterpoise corrections for the basis-set superposition error. However, the generalization of the counterpoise procedure to open-shell systems is ambiguous. Various generalized counterpoise schemes that have been proposed previously are shown to be related through different choices for diabatization of the monomer wave functions. We compare these generalized counterpoise schemes and show that only two approaches accurately describe long-range interactions. In addition, we propose an approximate diabatization algorithm based on the asymptotic long-range interaction. This approach is appealingly simple to implement as it yields analytical expressions for the transformation to the diabatic representation. Finally, we investigate the effects of diabatizing intermolecular potentials on the nuclear dynamics by performing quantum scattering calculations for NO(X 2 Π)-H 2. We show that cross sections for pure rotational transitions are insensitive to diabatization. For spin-orbit inelastic transitions, asymptotic diabatization and multiple-propertybased diabatization are in qualitative agreement, but the quantitative differences may be observable experimentally.

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“…The method was recently demonstrated in a report from Van de Meerakker and co-workers where it was used to reconstruct images of NO molecules scattering of He and D 2 . 25 0021-9606/2017/147(7)/074201/8/$30.00…”

Section: Introductionmentioning

confidence: 99%

Finite slice analysis (FINA) of sliced and velocity mapped images on a Cartesian grid

Thompson

Amarasinghe

Foley

et al. 2017

The Journal of Chemical Physics

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Although time-sliced imaging yields improved signal-to-noise and resolution compared with unsliced velocity mapped ion images, for finite slice widths as encountered in real experiments there is a loss of resolution and recovered intensities for the slow fragments. Recently, we reported a new approach that permits correction of these effects for an arbitrarily sliced distribution of a 3D charged particle cloud. This finite slice analysis (FinA) method utilizes basis functions that model the out-of-plane contribution of a given velocity component to the image for sequential subtraction in a spherical polar coordinate system. However, the original approach suffers from a slow processing time due to the weighting procedure needed to accurately model the out-of-plane projection of an anisotropic angular distribution. To overcome this issue we present a variant of the method in which the FinA approach is performed in a cylindrical coordinate system (Cartesian in the image plane) rather than a spherical polar coordinate system. Dubbed C-FinA, we show how this method is applied in much the same manner. We compare this variant to the polar FinA method and find that the processing time (of a 510 × 510 pixel image) in its most extreme case improves by a factor of 100. We also show that although the resulting velocity resolution is not quite as high as the polar version, this new approach shows superior resolution for fine structure in the differential cross sections. We demonstrate the method on a range of experimental and synthetic data at different effective slice widths.

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Imaging diffraction oscillations for inelastic collisions of NO radicals with He and D2

Cited by 20 publications

References 29 publications

Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard

Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard

Diabatic states, nonadiabatic coupling, and the counterpoise procedure for weakly interacting open-shell molecules

Finite slice analysis (FINA) of sliced and velocity mapped images on a Cartesian grid

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