Pade-approximant corrections to general variational expressions of scattering theory: Application to 5sigma photoionization of carbon monoxide

Journal Article · Thu Sep 01 04:00:00 EDT 1983 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.28.1382· OSTI ID:5541294

Lucchese, R R; McKoy, V

We discuss a method for systematically correcting results obtained using variational expressions in scattering theory. The approach taken is to compute a sequence of Pade approximants of the form (N/N) for the error in an initial variational estimate obtained using a basis-set expansion. The relationship between the Pade-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 Pade-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 5sigma photoionization of CO using the frozen-core Hartree-Fock and fixed-nuclei approximations. We find that the Pade-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.

• Research Organization: Department of Chemistry, Princeton University, Princeton, New Jersey 08544
• OSTI ID: 5541294
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 28:3; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CONVERGENCE
CORRECTIONS
CROSS SECTIONS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
EQUATIONS
INTEGRAL EQUATIONS
IONIZATION
MOLECULE COLLISIONS
OXIDES
OXYGEN COMPOUNDS
PADE APPROXIMATION
PHOTOIONIZATION
PHOTON COLLISIONS
PHOTON-MOLECULE COLLISIONS
SCATTERING
SCHWINGER VARIATIONAL METHOD
TOTAL CROSS SECTIONS
VARIATIONAL METHODS