Equivalent-core calculation of core-level relaxation energies in photoelectron spectroscopy: A molecular-orbital approach
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
The equivalent-core approximation is implemented in a novel way so as to calculate core-level relaxation energies in photoelectron spectroscopy. The method is based on self-consistent field (SCF) Hartree{endash}Fock molecular-orbital calculations via linear combinations of atomic orbitals, and involves evaluating the difference of sums of two-electron Coulomb and exchange integrals, for all electrons in an atom and in its equivalent-core ion. By thus avoiding SCF calculations with a core hole present (the true final state of photoemission), this procedure is shown to significantly save computing time in comparison with an exact SCF direct-hole calculation. Application of the method in single atoms and selected molecules shows about a 10{percent} difference with respect to direct-hole calculation results. The approximation introduces about 1{endash}6 eV errors compared to the experimental results of gas phase molecules. This method thus should be a generally useful procedure for estimating relaxation energies in core spectra. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 662176
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 16 Vol. 109; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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