Lucchese, Robert R. and McKoy, Vincent (1983) Padé-approximant corrections to general variational expressions of scattering theory: Application to 5σ photoionization of carbon monoxide. Physical Review A, 28 (3). pp. 1382-1394. ISSN 0556-2791 http://resolver.caltech.edu/CaltechAUTHORS:LUCpra83
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We discuss a method for systematically correcting results obtained using variational expressions in scattering theory. The approach taken is to compute a sequence of Padé approximants of the form [N/N] for the error in an initial variational estimate obtained using a basis-set expansion. The relationship between the Padé-approximant approach and the iterative Schwinger method for correcting variational estimates is also examined. We discuss a large class of general variational expressions to which the Padé-approximant approach can be applied. The variational expressions considered include those for the wave function, for photoionization transition matrix elements, as well as for scattering matrix (K-matrix) elements. We have applied this approach to the 5σ photoionization of CO using the frozen-core Hartree-Fock and fixed-nuclei approximations. We find that the Padé-approximant method converges rapidly and reliably. Both total photoionization cross sections and photoelectron angular distributions from threshold to 40 eV are presented and compared to previous experimental and theoretical results. We find major quantitative discrepancies between the present results for the total cross section and previous theoretical results.
|Additional Information:||©1983 The American Physical Society Received 15 December 1982 One of us (R.R.L.) would like to thank Herschel Rabitz for stimulating discussions concerning general variational expressions and for hospitality extended to him during his stay at Princeton University. This material is based upon work supported by the National Science Foundation under Grant No. PDF-81-66025 and Grant No. CHE-80-40870, and by the U.S. Office of Naval Research.|
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|Deposited On:||20 Dec 2006|
|Last Modified:||26 Dec 2012 09:24|
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