Multichannel quantum-defect theory and an equivalent<i>N</i>-level system

Cooke, W. E.; Cromer, Christopher L.

doi:10.1103/physreva.32.2725

Cited by 183 publications

(142 citation statements)

References 20 publications

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“…Rotated reference functions have previously been used to transform Y matrices in the study of atomic spectra [26][27][28][29][30] and atomic collisions [31]. Adjusting θ i at each energy such that Y ii = 0 was shown to produce a weak energy dependence of off-diagonal Y matrix elements across thresholds [31].…”

Section: Resultsmentioning

confidence: 99%

Optimized multichannel quantum defect theory for cold molecular collisions

2012

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Multichannel quantum defect theory (MQDT) can provide an efficient alternative to full coupled-channel calculations for low-energy molecular collisions. However, the efficiency relies on interpolation of the Y matrix that encapsulates the short-range dynamics, and there are poles in Y that may prevent interpolation over the range of energies of interest for cold molecular collisions. We show how the phases of the MQDT reference functions may be chosen so as to remove such poles from the vicinity of a reference energy and dramatically increase the range of interpolation. For the test case of Mg + NH, the resulting optimized Y matrix may be interpolated smoothly over an energy range of several Kelvin and a magnetic field range of over 1000 gauss. Calculations at additional energies and fields can then be performed at a computational cost that is proportional to the number of channels N and not to N 3 .

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Section: Resultsmentioning

confidence: 99%

Optimized multichannel quantum defect theory for cold molecular collisions

2012

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“…Q denotes the space composed of closed channels. The definitions of ν k and μ k can be found below (4). Each Beutler-Fano term in the sum on the right side of (2) takes the form of resonance scattering devoid of background scattering, suggesting that the index refers to pure resonance eigenchannels.…”

Section: Brief Introduction To the Previous Resultsmentioning

confidence: 99%

“…It begins from a factorization of the determinant of the physical scattering matrix S into background and resonance scattering 14,15 (4) where ν k is defined as with respect to the ionization threshold I k for the closed channel k; κ cc is a complex reactance matrix 16 defined in terms of the sub reactance matrix by . πμ denotes the phase shifts introduced by phase renormalization.…”

Section: Brief Introduction To the Previous Resultsmentioning

confidence: 99%

Effect of Open Channels on the Isolation of Overlapping Resonances in the Uniformly Perturbed Rydberg Systems Studied by Multichannel Quantum Defect Theory

Lee¹,

Kim²

2011

Bulletin of the Korean Chemical Society

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A previous study (Lee, C. W. J. Phys. B 2010, 43, 175002) that isolated the overlapping resonances in the photoionization spectra using multichannel quantum defect theory (MQDT) in systems involving a single open channel was extended to manage many open channels when the closed channels are degenerate. The theory was applied to the dipole allowed J = 1 o spectra from the ground state with excitation energies lying between the lowest ionization thresholds for rare gas atoms, Ar, Kr, and Xe, and also for group IV elements, Ge, Sn and Pb.

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“…We have omitted the energy dependence of Y matrix on purpose, to emphasize that the energy dependence of the scattering matrix is mainly governed by the energy variation of the parameters ξ(E) and ν(E) and that the resonances arise from the pole structure of equations (13,14). The Y matrix elements are expected to slowly vary with the energy, provided that the choice of reference functions is appropriate.…”

Section: Gmqdt Treatmentmentioning

confidence: 99%

“…We demonstrate that the optimization of the reference functions [12,13,14] based on a procedure introduced in ref. [15], leads to quantum defects with a weak energy dependence across the relevant energy threshold, just like in the standard MQDT situation.…”

Section: Introductionmentioning

confidence: 99%

Optimization of generalized multichannel quantum defect reference functions for Feshbach resonance characterization

Osseni¹,

Dulieu²,

Raoult³

2009

J. Phys. B: At. Mol. Opt. Phys.

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This work stresses the importance of the choice of the set of reference functions in the Generalized Multichannel Quantum Defect Theory to analyze the location and the width of Feshbach resonance occurring in collisional cross-sections. This is illustrated on the photoassociation of cold rubidium atom pairs, which is also modeled using the Mapped Fourier Grid Hamiltonian method combined with an optical potential. The specificity of the present example lies in a high density of quasi-bound states (closed channel) interacting with a dissociation continuum (open channel). We demonstrate that the optimization of the reference functions leads to quantum defects with a weak energy dependence across the relevant energy threshold. The main result of our paper is that the agreement between the both theoretical approaches is achieved only if optimized reference functions are used.

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Multichannel quantum-defect theory and an equivalentN-level system

Cited by 183 publications

References 20 publications

Optimized multichannel quantum defect theory for cold molecular collisions

Optimized multichannel quantum defect theory for cold molecular collisions

Effect of Open Channels on the Isolation of Overlapping Resonances in the Uniformly Perturbed Rydberg Systems Studied by Multichannel Quantum Defect Theory

Optimization of generalized multichannel quantum defect reference functions for Feshbach resonance characterization

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