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Manuscript Title: A program for analysing the Rydberg series of highly excited discrete spectra by M.Q.D.T.
Authors: O. Robaux, M. Aymar
Program title: MQDTAC
Catalogue identifier: AANQ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 25(1982)223
Programming language: Fortran.
Computer: UNIVAC 1110.
Operating system: EXEC VIII.
RAM: 25K words
Word size: 36
Keywords: Atomic physics, Spectroscopy, Rydberg levels, Multichannel quantum Defect theory.
Classification: 2.2.

Nature of problem:
A collision theory analysis of highly perturbed spectra has been recently developed by Fano which relies on Seaton's Multichannel Quantum Defect Theory (M.Q.D.T.). Various photoabsorption data relevant to discrete, autoionization and continuous spectra can be expressed in terms of three sets of meaningful parameters. The program enables several atomic quantities to be computed in terms of these M.Q. D.T. parameters (mualpha, Uialpha, Dalpha). The mualpha and Uialpha parameters relevant to the calculation of energies are determined from data on perturbed Rydberg series while the Dalpha needed to calculate oscillator strengths are given as input. Graphical analysis of perturbed Rydberg series is performed by means of Lu-Fano curves.

Solution method:
The Mualpha and Uialpha parameters are optimized through an iterative process according to one of the following quality criteria (available as input): a) minimisation of the rms derivation between theoretical and experimental energies of discrete levels. b) minimisation of a sum of determinants characteristic of the M.Q.D.T.

The maximum number of series converging to the first ionisation limit is limited to 3. -Autoionisation profiles are computed for the levels lying in the energy range between the first two limits of ionisation, -Branching ratio is given for the case of only two different ionic states (noble gases).