Programs in Physics & Physical Chemistry
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|Manuscript Title: The QB program: analysing resonances using R-matrix theory.|
|Authors: L. Quigley, K.A. Berrington, J. Pelan|
|Program title: QB|
|Catalogue identifier: ADJC_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 114(1998)225|
|Programming language: Fortran.|
|Computer: DEC workstation.|
|Operating system: Unix (HP-UX/ Linux/ Unicos).|
|RAM: 5M words|
|Word size: 64|
|Keywords: Atomic physics, Electron atom, Scattering, Electron ion scattering, Photoionization, Resonance, R-matrix, General purpose, Fit.|
|Classification: 2.4, 4.9.|
Nature of problem:
A procedure for analysing resonances in atomic and molecular collision theory is programmed, which exploits the analytic properties of R-matrix theory to obtain the energy derivative of the reactance (K) matrix and hence the eigenphase sum derivative. Searching for maxima in this gives positions, widths and identifications for all resonances in a given energy range.
This procedure is based on the QB method  which defines matrices Q and B in terms of asymptotic solutions, the R-matrix and energy derivatives, such that dK/dE = B**-1Q, from which eigenphase gradients of the K matrix can be obtained. Resonance positions are defined at the points of maximum gradient; resonance widths are related to the inverse of the eigenphase gradients: resonance identifications are estimated from outer region solutions.
The present version is for input specified by the 'H-file' of RMATRX1  and is for ionic targets only; a more appropriate asymptotic program is needed for the case of negative ion resonances.
The test run takes 2s on a HP735 workstation.
|||K.A. Berrington, W.B. Eissner and P.H. Norrington, Comput. Phys. Commun. 92 (1995) 290.|
|||L. Quigley and K.A. Berrington, J. Phys. B: At. Mol. Opt. Phys. 29 (1996) 4529.|
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