Methods for the calculation of photoionization cross sections using the extended Koopman's Theorem

Journal Article · Sat Jan 01 04:00:00 EST 1977 · Int. J. Quant. Chem., Symp.; (United States)

OSTI ID:6759940

Chipman, D M

A new approach to the calculation of photoionization cross sections for atoms and molecules is described. The procedure requires for input only a wave function for the parent initial state, obviating the necessity of a separate calculation on the final bound state by making use of the recently developed Extended Koopmans' Theorem. Explicit formulas for the photoionization cross sections, in terms of the one- and two-particle reduced density matrices of the initial state wave function, have been obtained at several levels of sophistication, including the sudden approximation, an orbital model for the photoelectron, and a close-coupling model. In the latter two cases, equations have been derived for the optimization of the continuum orbitals required for the description of the outgoing photoelectron. Approximations which make the optimization equations more tractable are also discussed. 26 references.

• Research Organization: Univ. of Notre Dame, IN
• OSTI ID: 6759940
• Journal Information: Int. J. Quant. Chem., Symp.; (United States), Journal Name: Int. J. Quant. Chem., Symp.; (United States) Vol. 11; ISSN IJQSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ATOMS
CALCULATION METHODS
CROSS SECTIONS
DENSITY MATRIX
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
FUNCTIONS
IONIZATION
MATHEMATICAL MODELS
MATRICES
MOLECULES
OPTIMIZATION
PARTICLE MODELS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
SPECTROSCOPY
STRONG-COUPLING MODEL
SUDDEN APPROXIMATION
WAVE FUNCTIONS